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Declining Rainfall in Cherrapunji

Why in News A recent study that looked at the rainfall pattern in the past 119 years found a decreasing trend at Cherrapunji (Meghalaya) and nearby...

22 Feb 2021 Important Geophysical Phenomena
Deglaciation and Threats

Deglaciation Glaciers, ice caps and continental ice sheets cover some 10% of the earth’s land surface at the present time, whereas during...

22 Feb 2021 Important Geophysical Phenomena
Glaciers

About A glacier is a large, perennial accumulation of crystalline ice, snow, rock, sediment, and water that originates on land and moves down...

15 Feb 2021 Important Geophysical Phenomena
Mapping Seismic Hazard of Eastern Himalaya

Why in News Recently, scientists have found the first geological evidence of an earthquake on the border of Assam and Arunachal Pradesh, documented...

09 Feb 2021 Important Geophysical Phenomena
Pacific Ring of Fire

The Ring of Fire, also referred to as the Circum-Pacific Belt, is a path along the Pacific Ocean characterized by active volcanoes and frequent...

08 Feb 2021 Important Geophysical Phenomena
Tectonic Plates

Tectonic Plates A tectonic plate (also called lithospheric plate) is a massive, irregularly-shaped slab of solid rock, generally composed of both...

01 Feb 2021 Important Geophysical Phenomena
El Nino and La Nina

El Nino and La Nina are complex weather patterns resulting from variations in ocean temperatures in the Equatorial Pacific Region. They are...

18 Jan 2021 Important Geophysical Phenomena
Semeru Volcano of Indonesia

Why in News Recently, Semeru volcano erupted in Indonesia’s East Java province. Other volcanoes, such as the Merapi volcano (Java) and...

18 Jan 2021 Important Geophysical Phenomena
Winter Solstice

Why in News 21st December or the Winter Solstice marks the shortest day of the year in the Northern Hemisphere. The same day marks the Summer...

22 Dec 2020 Important Geophysical Phenomena
El Niño & Drought

Why in News In a recent study by Indian Institute of Science’s (IISc) Centre for Atmospheric and Oceanic Sciences (CAOS), it has been found...

14 Dec 2020 Important Geophysical Phenomena
Cyclone Burevi

Why in News Recently cyclone Burevi has made a landfall on Sri Lanka’s Northern and Eastern provinces, before heading towards south...

04 Dec 2020 Important Geophysical Phenomena
Provisional Report on the State of the Global Climate 2020: WMO

Why in News According to the latest State of the Global Climate provisional report by the World Meteorological Organization (WMO), the year 2020 is...

04 Dec 2020 Important Geophysical Phenomena
Subdued Northeast Monsoon

Why in News Rainfall over the southern peninsular region has been deficient so far, indicating that the northeast monsoon has remained subdued this...

26 Nov 2020 Important Geophysical Phenomena
Cyclone Nivar

Why in News Recently, the tropical cyclone Nivar has made landfall along the Tamil Nadu-Puducherry coast. Landfall refers to the phenomenon of a...

26 Nov 2020 Important Geophysical Phenomena
Earthquake Concentrations in Dharchula Region

Why in News Recently, scientists at Wadia Institute of Himalayan Geology (WIHG) have unearthed large concentrations of micro and moderate magnitude...

10 Nov 2020 Important Geophysical Phenomena
Hurricane Eta

Why in News Recently, Hurricane Eta has hit northeastern Nicaragua with life-threatening storm surge, catastrophic winds and flash flooding...

05 Nov 2020 Important Geophysical Phenomena
Tectonically Active Zone of Himalayas

Why in News Recently, a group of scientists from the Wadia Institute of Himalayan Geology (WIHG), Dehradun have found that the Indus-Tsangpo Suture...

28 Oct 2020 Important Geophysical Phenomena
World Risk Index 2020

Why in News According to the World Risk Index (WRI) 2020, India is ‘poorly prepared’ to deal with ‘climate reality’, due to...

24 Sep 2020 Important Geophysical Phenomena
Typhoon Maysak and Typhoon Haishen

Why in News Recently, Korean Peninsula and Japan were hit by two typhoons named Maysak and Haishen. Typhoons Typhoons are a kind of storm. The...

10 Sep 2020 Important Geophysical Phenomena
Temperature Inversion

Meaning Under normal conditions, temperature usually decreases with increase in altitude in the troposphere at a rate of 1 degree for every 165...

29 Aug 2020 Important Geophysical Phenomena

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		'title' => 'Declining Rainfall in Cherrapunji',
		'description' => '<h3>Why in News</h3>
<p>A recent study that looked at the <strong>rainfall pattern in the past 119 years</strong> found a <strong>decreasing trend at Cherrapunji (Meghalaya) and nearby areas.</strong></p>
<ul style="list-style-type: square;">
<li>The village of <strong>Mawsynram in East Khasi Hills district of Meghalaya</strong> has beaten Cherrapunji to become the <strong>wettest place in the world.</strong> Mawsynram receives over 10,000 millimetres of rain in a year.</li>
<li>Mawsynram is located around <strong>81 km by road from Cherrapunji</strong> however the straight line distance between the two is <strong>15.2 km.</strong></li>
</ul>
<p><a href="http://www.drishtiias.com/images/uploads/1613980587_image1.png" target="_blank" rel="noopener"><strong><img class="content-img" src="http://www.drishtiias.com/images/uploads/1613980587_image1.png" style="display: block; margin-left: auto; margin-right: auto;" width="400" caption="false" /></strong></a></p>
<h3>Key Points</h3>
<ul style="list-style-type: square;">
<li><strong>Reduction in Rainfall:</strong>
<ul style="list-style-type: circle;">
<li>The <strong>annual mean rainfall</strong> for the period <strong>1973&ndash;2019</strong> showed <strong>decreasing trends</strong> of about <strong>0.42 mm per decade.</strong>
<ul style="list-style-type: disc;">
<li>It was statistically significant along seven stations <strong>(Agartala, Cherrapunji, Guwahati, Kailashahar, Pasighat, Shillong and Silchar).</strong></li>
</ul>
</li>
</ul>
</li>
<li><strong>Reasons:</strong><br />
<ul style="list-style-type: circle;">
<li><strong>Rising Temperature:</strong><br />
<ul style="list-style-type: disc;">
<li>The <strong>changes in the Indian Ocean temperature</strong> have a <strong>huge effect</strong> on the rainfall in the region.<br />
<ul style="list-style-type: disc;">
<li>Increasing sea surface temperatures in the tropical Indian Ocean region was pointed out by the <a href="/daily-updates/daily-news-analysis/assessment-of-climate-change-over-the-indian-region-moes" target="_blank" rel="noopener"><strong>first climate change assessment report</strong></a> published by the Union Ministry of Earth Sciences in June 2020.</li>
</ul>
</li>
</ul>
</li>
<li><strong>Increased Human Activities:</strong><br />
<ul style="list-style-type: disc;">
<li>The satellite data showed that there was a <strong>reduction in the vegetation area</strong> in northeast India in the past two decades, implying that human influence also plays an important role in the changing rainfall patterns.<br />
<ul style="list-style-type: disc;">
<li>The traditional way of cultivation known as <a href="/daily-updates/daily-news-analysis/niti-aayog-report-on-shifting-cultivation" target="_blank" rel="noopener"><strong>Jhum cultivation or shifting cultivation</strong></a> is now decreased and being replaced by other methods.</li>
<li>There is sizable <a href="/daily-updates/daily-news-analysis/deforestation-rate-declined"><strong>deforestation</strong></a> in the region. The study saw the <strong>decrease in vegetation cover and increase in the areas of cropland</strong> mainly from the year 2006 onwards.</li>
<li>The analysis showed <strong>reductions in vegetation</strong> with <strong>104.5 sqkm lost per year.</strong></li>
<li>On the other hand, there were <strong>significant increases in cropland</strong> (182.1 sqkm per year) and <strong>urban and built-up lands</strong> (0.3 sqkm per year) during the period 2001&ndash;2018.</li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
<li><strong>Significance of Studying the North-East Region:</strong><br />
<ul style="list-style-type: circle;">
<li>Since north-east India is mostly hilly and is an extension of the Indo-Gangetic Plains, the <strong>region is highly sensitive to changes</strong> in regional and global climate.</li>
<li>It has to be noted that the <strong>first signs of the effect of <a href="/daily-updates/daily-news-editorials/climate-change-and-development-in-india" target="_blank" rel="noopener">climate change</a></strong> will be evident for the extreme cases such as the rainfall at Cherrapunji.</li>
<li>North-east India has the <strong>highest vegetation cover</strong> in India and includes <strong>18 biodiversity hotspots of the world</strong>, indicating the importance of the region in terms of its greenery and <strong>climate-change sensitivity.</strong></li>
</ul>
</li>
</ul>
<div class="border-bg">
<p><strong>Reason for High Rainfall in Cherrapunji and Mawsynram</strong></p>
<ul style="list-style-type: square;">
<li><strong>Cherrapunji (elevation 1313 m)</strong> and <strong>Mawsynram (elevation 1401.5 m)</strong> are located on the southern slopes of the east Khasi Hills in Meghalaya. <br />
<ul style="list-style-type: circle;">
<li>Meghalaya is a mountainous state with <strong>numerous valleys and highland plateaus.</strong></li>
<li><strong>Elevation</strong> in the plateau region ranges between <strong>150 m</strong> to <strong>1,961 m ,</strong> with the central part comprising the Khasi Hills with the highest elevations.</li>
</ul>
</li>
<li>The rainfall in Cherrapunji-Mawsynram is <strong>caused by the orography favouring a monsoon wind regime.</strong></li>
<li>The northward moving moist winds from the Bay of Bengal passing over the plains of Bangladesh are <strong>forced to converge in the narrow valleys of the Khasi Hills</strong> with orography providing forced ascent that causes condensation, formation of clouds resulting in rain on the windward side of the slope.</li>
</ul>
<p><strong>Shifting Cultivation</strong></p>
<ul style="list-style-type: square;">
<li>Shifting cultivation, locally called 'Jhum', is a widely practiced system of crop cultivation among the indigenous communities of North-east India. The practice, also known as <strong>slash-and-burn agriculture</strong>, is when farmers clear land by slashing vegetation and burning forests and woodlands to create clear land for agricultural purposes.</li>
<li>This provides a <strong>very easy and very fast method</strong> of the preparation of the land for agriculture.</li>
<li>The bush and the weeds can be removed easily. The <strong>burning of waste materials provides needed nutrients for the cultivation.</strong></li>
<li>It <strong>gives</strong> a family its <strong>food, fodder, fuel, livelihood</strong> and is closely linked to their identity.</li>
<li>Because of cutting of forests and trees, this practice <strong>leads to soil erosion and may also affect the course of rivers.</strong></li>
</ul>
</div>
<p><a href="https://www.thehindu.com/sci-tech/science/wettest-place-on-earth-sees-decreasing-trend-in-rainfall/article33889697.ece#:~:text=The%20quiet%2C%20sleepy%2C%20yet%20mesmerising,to%20The%20Hindu%20subscribers%20only." target="_blank" rel="noopener"><strong>Source:TH</strong></a></p>',
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		'category_id' => (int) 26,
		'title' => 'Deglaciation and Threats',
		'description' => '<h3>Deglaciation </h3>
<ul style="list-style-type: square;">
<li>Glaciers, ice caps and continental ice sheets <strong>cover some 10% of the earth&rsquo;s land surface</strong> at the present time, whereas during the ice ages, they covered about three times this amount <br />
<ul style="list-style-type: circle;">
<li>The present ice cover corresponds to about three-quarter of the world&rsquo;s total freshwater resources. </li>
</ul>
</li>
<li>The gradual melting away of a glacier from the surface of a landmass is known as <strong>Deglaciation.</strong><br />
<ul style="list-style-type: circle;">
<li>The processes that remove snow, ice, and moraine from a glacier or ice sheet are called <strong>Ablation.</strong> <br />
<ul style="list-style-type: disc;">
<li>It includes melting, evaporation, erosion, and calving.</li>
</ul>
</li>
</ul>
</li>
<li>The process of deglaciation, that intensified in the 20th century, is leaving our planet iceless. </li>
</ul>
<h3>Causes of Deglaciation</h3>
<ul style="list-style-type: square;">
<li><strong>Global warming:</strong> The atmospheric concentration of carbon dioxide, methane and other greenhouse gases (GHGs) produced by <strong>industry, transport, deforestation and burning fossil fuels,</strong> amongst other human activities, <strong>warm the planet and cause glaciers to melt.</strong></li>
<li><strong>Ocean warming:</strong> Oceans absorb 90% of the Earth's warmth, and this affects the melting of marine glaciers, which are mostly located near the poles.</li>
<li><strong>Rapid industrialisation:</strong> Since the early 1900s, many glaciers around the world have been rapidly melting, <strong>specifically, since the industrial revolution,</strong> carbon dioxide and other<strong> greenhouse gas emissions have raised temperatures,</strong> even <strong>higher in the poles,</strong> and as a result, glaciers are rapidly melting, calving off into the sea and retreating on land.</li>
</ul>
<h3>Impacts of Deglaciation</h3>
<ul style="list-style-type: square;">
<li><strong>Raised sea level:</strong> The melting glaciers have played the major role in<strong> raising average global sea level between four and eight inches</strong> (10 and 20 centimeters) in the past hundred years, according to the <a href="/daily-updates/daily-news-analysis/special-report-on-climate-change-ipcc" target="_blank" rel="noopener"><strong>Intergovernmental Panel on Climate Change (IPCC).</strong></a><br />
<ul style="list-style-type: circle;">
<li>Rising sea levels increase coastal erosion and elevates storm surge as warming air and ocean temperatures create more frequent and intense coastal storms like hurricanes and typhoons.</li>
</ul>
</li>
<li><strong>On mountain glaciers:</strong> The famed snows of <strong>Kilimanjaro</strong> have melted more than 80% since 1912. <br />
<ul style="list-style-type: circle;">
<li><strong>Glaciers in the Garhwal region</strong> of the Himalayas are retreating so fast that researchers believe that most central and eastern Himalayan glaciers could virtually disappear by 2035. </li>
</ul>
</li>
<li><strong>In the Northern Hemisphere:</strong> Spring freshwater ice breakup in the Northern Hemisphere now<strong> occurs nine days earlier</strong> than it did 150 years ago, and <strong>autumn freeze-up ten days later. </strong><br />
<ul style="list-style-type: circle;">
<li><strong>Arctic sea</strong> ice has thinned significantly over the past half century, and its extent has declined by about 10% in the past 30 years. </li>
<li>The <strong>Greenland</strong> ice sheet is disappearing four times faster than in 2003 and already contributes 20% of current sea level rise.</li>
</ul>
</li>
<li><strong>Melting of Thwaites Glacier:</strong> Also called <a href="/daily-updates/daily-news-analysis/melting-of-thwaites-glacier" target="_blank" rel="noopener"><strong>Doomsday Glacier</strong></a>, it is a 120 km wide, fast-moving glacier located in <strong>Antarctica.</strong><br />
<ul style="list-style-type: circle;">
<li>Because of its size (1.9 lakh square km), it contains enough water to raise the world sea level by more than half a metre.</li>
<li>Studies have detected the <strong>presence of warm water</strong> at a vital point beneath the Thwaites glacier as the cause of its melting.</li>
<li>Its <strong>melting already contributes 4% to global sea-level rise each year.</strong> It is estimated that it would collapse into the sea in 200-900 years.<br />
<ul style="list-style-type: disc;">
<li>Studies have found the amount of ice flowing out of it has nearly doubled over the past 30 years.</li>
</ul>
</li>
</ul>
</li>
<li><strong>Disappearance of species:</strong> Glaciers are the natural habitat of a number of animals, both terrestrial and aquatic, if the melting continues at the same rate, a number of species will become extinct.<br />
<ul style="list-style-type: circle;">
<li>It will also disturb the balance of the food chain.</li>
</ul>
</li>
</ul>
<p><a href="http://www.drishtiias.com/images/uploads/1613974001_image1.jpg" target="_blank" rel="noopener"><img class="content-img" src="http://www.drishtiias.com/images/uploads/1613974001_image1.jpg" style="display: block; margin-left: auto; margin-right: auto;" width="550" caption="false" /></a></p>
<h3>The Himalayan Glaciers</h3>
<p><strong>About</strong></p>
<ul style="list-style-type: square;">
<li>Himalayan glaciers form the largest body of ice outside the polar caps and are the source of water for the innumerable rivers that flow across the Indo-Gangetic plains. <br />
<ul style="list-style-type: circle;">
<li>Himalayan glaciers are also known as the Third Pole. </li>
</ul>
</li>
<li>Himalayan glacial snowfields store about 12,000 km3 of freshwater. </li>
<li>15,000 Himalayan glaciers form a unique reservoir which supports perennial rivers such as the Indus, Ganga and Brahmaputra which, in turn, are the lifeline of millions of people in South Asian countries (Pakistan, Nepal, Bhutan, India and Bangladesh). </li>
<li>The Gangetic basin alone is home to 500 million people, about 10% of the total human population in the region.</li>
</ul>
<p><strong>The Receding Glaciers</strong></p>
<ul style="list-style-type: square;">
<li><strong>Rate of receding:</strong> Glaciers in the Himalaya are receding faster than in any other part of the world. <br />
<ul style="list-style-type: circle;">
<li>The glaciers have been losing the equivalent of more than a vertical foot and half of ice each year since 2000; double the amount of melting that took place from 1975 to 2000.</li>
<li>According to the statistics in the last 25 years approximate 400 crore tons of ice being melted in the Himalayan glaciers.</li>
<li>The 30.2 km long <a href="/daily-updates/daily-news-analysis/concentration-of-black-carbon-on-gangotri-glacier" target="_blank" rel="noopener"><strong>Gangotri Glacier</strong> </a>has been receding alarmingly in recent years.</li>
</ul>
</li>
<li><strong>Cause of receding:</strong> The receding and thinning of Himalayan glaciers can be attributed primarily to global warming due to increase in anthropogenic emission of greenhouse gases. <br />
<ul style="list-style-type: circle;">
<li>The relatively high population density near these glaciers and consequent deforestation and land-use changes have also adversely affected these glaciers. </li>
</ul>
</li>
<li><strong>Effect on the Hindukush region:</strong> Climate change has hastened glacial melting across the <a href="/daily-updates/daily-news-analysis/hindu-kush-himalayan-region" target="_blank" rel="noopener"><strong>Hindu Kush Himalayan (HKH) region</strong></a>, home to some of the world&rsquo;s tallest peaks, including Mount Everest.<br />
<ul style="list-style-type: circle;">
<li>The recent <a href="/daily-updates/daily-news-analysis/uttarakhand-flash-flood" target="_blank" rel="noopener"><strong>glacier collapse at Nanda Devi</strong></a> in Uttarakhand&rsquo;s Chamoli district led to a massive flood in the Dhauli Ganga river and caused large-scale devastation in the upper reaches of the ecologically fragile Himalayas.</li>
</ul>
</li>
<li><strong>Air warming over HKH:</strong> Air over HKH warmed at a rate of 0.2℃ each decade from 1951 to 2014 and at an even higher rate of 0.5℃ per decade at elevations higher than 4,000 meters, as per a report prepared by the Ministry of Earth Sciences (MoES). <br />
<ul style="list-style-type: circle;">
<li>The report projected that even with the Indian government&rsquo;s commitment to mitigate greenhouse gases by 2030, the Indian Himalayas could warm by 2.6℃&ndash;4.6℃ by 2100. </li>
<li>In the worst-case scenario, the mean surface temperature over the whole region could rise by 5.2℃ by 2100.</li>
</ul>
</li>
</ul>
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		'article_id' => (int) 7688,
		'category_id' => (int) 26,
		'title' => 'Glaciers',
		'description' => '<h3>About</h3>
<ul style="list-style-type: square;">
<li>A glacier is a large, <strong>perennial accumulation of crystalline ice, snow, rock, sediment,</strong> and <strong>water</strong> that originates on land and moves down slope under the influence of its own weight and gravity. They are <strong>sensitive indicators of changing climate.</strong></li>
<li>Out of total water on Earth, <strong>2.1% is in glaciers while 97.2% is in the oceans</strong> and inland seas.</li>
<li><strong>Condition of glacier formation:</strong><br />
<ul style="list-style-type: circle;">
<li><strong>Mean annual temperatures</strong> are close to the freezing point.</li>
<li><strong>Winter precipitation</strong> produces significant accumulations of snow.</li>
<li><strong>Temperatures throughout the rest of the year</strong> do not result in the complete loss of the previous winter&rsquo;s snow accumulation.</li>
</ul>
</li>
</ul>
<p><strong>Formation of Glacier</strong></p>
<ul style="list-style-type: square;">
<li>Glaciers begin forming in places where more snow piles up each year than melts. Soon after falling, the snow begins to compress, or become denser and tightly packed.<br />
<ul style="list-style-type: circle;">
<li>The process of snow compacting into glacial firn (dense, grainy ice) is called <strong>firnification</strong>.</li>
</ul>
</li>
<li>When the ice grows thick enough, about 50 meters (160 feet), the firn grains fuse into a huge mass of solid ice. The glacier begins to move under its own weight.<br />
<ul style="list-style-type: circle;">
<li>Different parts of a glacier move at different speeds. The flowing ice in the middle of the glacier moves faster than the base.</li>
</ul>
</li>
</ul>
<p><strong>Geographical Location</strong></p>
<ul style="list-style-type: square;">
<li><strong>91%</strong> of the Glaciers are in <strong>Antarctica</strong> and <strong>8%</strong> are in <strong>Greenland.</strong> They occupy about 10% of the world's total land area.</li>
</ul>
<p><a href="http://www.drishtiias.com/images/uploads/1613373504_image1.png" target="_blank" rel="noopener"><img class="content-img" src="http://www.drishtiias.com/images/uploads/1613373504_image1.png" width="600" caption="false" style="display: block; margin-left: auto; margin-right: auto;" /></a></p>
<p><strong>Significance:</strong></p>
<ul style="list-style-type: square;">
<li><strong>Glaciers as Reservoirs:</strong> About <strong>three-quarters</strong> of Earth's freshwater is stored in glaciers. Therefore, glacier ice is the <strong>second largest reservoir of water</strong> on Earth and the <strong>largest reservoir of freshwater</strong> on Earth.<br />
<ul style="list-style-type: circle;">
<li>The cold runoff from glaciers also affects downstream water temperatures.</li>
</ul>
</li>
<li><strong>Glaciers feeding Rivers:</strong> The <strong>Gangotri Glacier</strong>, one of the largest glaciers in the Himalayan Mountains, is <strong>the source of the Ganga River</strong>. <br />
<ul style="list-style-type: circle;">
<li>The Ganges is the most important source of freshwater and electricity in India and Bangladesh.</li>
</ul>
</li>
<li><strong>Glaciers for Aquatic Life:</strong> Many <strong>aquatic species in mountainous environments</strong> require cold water temperatures to survive which is provided by Glaciers. <br />
<ul style="list-style-type: circle;">
<li>Some <strong>aquatic insects</strong> are <strong>especially sensitive to stream temperature</strong> and cannot survive without the cooling effects of glacial meltwater.</li>
<li>Such changes in stream habitat may also <strong>adversely impact native trout</strong> and other <strong>keystone salmon species.</strong></li>
</ul>
</li>
<li><strong>Glaciers for People:</strong> Glaciers provide people with many useful resources. Glacial till <strong>provides fertile soil for growing crops</strong>.<br />
<ul style="list-style-type: circle;">
<li>Deposits of sand and gravel are used to make <strong>concrete and asphalt</strong>.</li>
</ul>
</li>
</ul>
<h3>Classification of Glaciers</h3>
<ul style="list-style-type: square;">
<li>Glaciers can be classified according to their: <br />
<ul style="list-style-type: circle;">
<li><strong>Size</strong> (i.e. ice sheet, ice cap, valley glacier, cirque glacier)</li>
<li><strong>Thermal regime</strong> (polar vs. temperate).</li>
</ul>
</li>
</ul>
<p><strong>Size Based</strong></p>
<ul style="list-style-type: square;">
<li><strong>Ice Cap:</strong> An ice cap is a dome-shaped glacier mass flowing in all directions, such as the ice cap on Ellesmere Island in the Canadian Arctic. <br />
<ul style="list-style-type: circle;">
<li>There is still some <strong>uncertainty about the full volume of glaciers and ice caps</strong> on Earth, but if all of them were to melt, <strong>global sea level would rise approximately 70 meters</strong> (approximately 230 feet), flooding every coastal city on the planet.</li>
</ul>
</li>
<li><strong>Valley Glaciers:</strong> Also called <strong>Alpine Glaciers</strong> or <strong>Mountain Glaciers</strong>, they form on mountainsides and move downward through valleys. <br />
<ul style="list-style-type: circle;">
<li>They are <strong>found in high mountains</strong> <strong>of every continent except Australia</strong> (although there are many in New Zealand). <br />
<ul style="list-style-type: disc;">
<li>Example: The <strong>Gorner Glacier in Switzerland</strong> and the <strong>Furtwangler Glacier in Tanzania</strong>.</li>
</ul>
</li>
</ul>
</li>
<li><strong>Ice Sheets:</strong> Unlike valley glaciers, ice sheets are not limited to mountainous areas. They form broad domes and spread out from their centers in all directions. <br />
<ul style="list-style-type: circle;">
<li>As ice sheets spread, they cover everything around them with a thick blanket of ice, including valleys, plains, and even entire mountains.</li>
<li>The largest ice sheets, called <strong>continental glaciers</strong>, spread over vast areas. <br />
<ul style="list-style-type: disc;">
<li>Continental glaciers <strong>cover most of Antarctica and the island of Greenland</strong>.</li>
</ul>
</li>
</ul>
</li>
<li><strong>Cirque glaciers:</strong> They are short and wide, are confined to cirques, or amphitheatres, cut in the mountain landscape.</li>
</ul>
<p><strong>Thermal Regime based:</strong></p>
<ul style="list-style-type: square;">
<li><strong>Polar Glacier:</strong> A polar glacier is defined as one that is below the freezing temperature throughout its mass for the entire year.<br />
<ul style="list-style-type: circle;">
<li>A subpolar glacier contains ice below the freezing temperature, except for surface melting in the summer and a basal layer of temperate ice.</li>
</ul>
</li>
<li><strong>Temperate Glacier:</strong> A temperate glacier is the one that&rsquo;s <strong>essentially at the melting point</strong>, so liquid water coexists with glacier ice. <br />
<ul style="list-style-type: circle;">
<li>They are found in North America, South America, Europe, Africa, and <strong>Asia</strong> and <strong>New Zealand.</strong> <br />
<ul style="list-style-type: disc;">
<li>Some of the <strong>Antarctic glaciers</strong> and <strong>Greenland&rsquo;s southern outlet glaciers</strong> are temperate.</li>
</ul>
</li>
</ul>
</li>
</ul>
<h3>Landforms Formed</h3>
<p><strong>Erosional Landforms</strong><br /><strong></strong></p>
<ul style="list-style-type: square;">
<li><strong>Glacial Valleys/Troughs:</strong> These valleys are <strong>trough-like and U-shaped</strong> with broad floors and relatively smooth, and steep sides. <br />
<ul style="list-style-type: circle;">
<li>The valleys may contain littered debris or debris shaped as <strong>moraines</strong> with swampy appearance.</li>
<li>Very deep glacial troughs filled with sea water and making up shorelines (in high latitudes) are called <strong>fjords/fiords.</strong></li>
</ul>
</li>
<li><strong>Cirques:</strong> Often are found at the heads of glacial valleys, these are the most common of landforms in glaciated mountains. <br />
<ul style="list-style-type: circle;">
<li>They are <strong>deep, long and wide troughs</strong> or basins with very steep concave to vertically dropping high walls at its head as well as sides.</li>
<li>A lake of water can be seen quite often within the cirques after the glacier disappears. Such lakes are called <strong>cirque lakes or tarn lakes.</strong></li>
</ul>
</li>
<li><strong>Horns and Serrated:</strong> Ridges Horns form through headward erosion of the cirque walls. <br />
<ul style="list-style-type: circle;">
<li>If three or more radiating glaciers cut headward until their cirques meet, high, sharp pointed and steep sided peaks called horns form.</li>
</ul>
</li>
</ul>
<p><strong>Depositional Landforms:</strong></p>
<ul style="list-style-type: square;">
<li><strong>Glacial Till:</strong> The unassorted coarse and fine debris dropped by the melting glaciers is called glacial till. <br />
<ul style="list-style-type: circle;">
<li>Some amount of rock debris small enough to be carried by such melt-water streams is washed down and deposited. <br />
<ul style="list-style-type: disc;">
<li>Such glaciofluvial deposits are called <strong>outwash deposits</strong>.</li>
<li>The outwash deposits are roughly stratified and assorted.</li>
</ul>
</li>
</ul>
</li>
<li><strong>Moraines:</strong> They are <strong>long ridges of deposits of glacial till.</strong> <br />
<ul style="list-style-type: circle;">
<li><strong>Terminal moraines</strong> are long ridges of debris deposited at the end (toe) of the glaciers.</li>
<li>Lateral moraines form along the sides parallel to the glacial valleys.</li>
<li>Many valley glaciers retreating rapidly leave an irregular sheet of till over their valley floors called <strong>ground moraines.</strong></li>
<li>The moraine in the centre of the glacial valley flanked by lateral moraines is called <strong>medial moraine.</strong> <br />
<ul style="list-style-type: disc;">
<li>They are imperfectly formed as compared to lateral moraines. Sometimes medial moraines are indistinguishable from ground moraines.</li>
</ul>
</li>
</ul>
</li>
<li><strong>Eskers:</strong> These are ridges made of sands and gravels, deposited by glacial meltwater flowing through tunnels within and underneath glaciers, or through meltwater channels on top of glaciers.<br />
<ul style="list-style-type: circle;">
<li>Over time, the channel or tunnel gets filled up with sediments. As the ice retreats, the sediments are left behind as a ridge in the landscape.</li>
</ul>
</li>
<li><strong>Drumlins:</strong> They are <strong>smooth oval shaped ridge-like features</strong> composed mainly of glacial till with some masses of gravel and sand. <br />
<ul style="list-style-type: circle;">
<li>The long axes of drumlins are parallel to the direction of ice movement.</li>
<li>They may measure up to 1 km in length and 30 m or so in height.</li>
<li>The drumlin end facing the glacier is called the stoss end and is blunter and steeper than the other end called tail.&nbsp;</li>
</ul>
</li>
</ul>
<p><a href="http://www.drishtiias.com/images/uploads/1613374293_Image1.PNG" target="_blank" rel="noopener"><img class="content-img" src="http://www.drishtiias.com/images/uploads/1613374293_Image1.PNG" style="display: block; margin-left: auto; margin-right: auto;" width="600" caption="false" /></a></p>',
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	(int) 3 => object(Cake\ORM\Entity) {

		'article_id' => (int) 7649,
		'category_id' => (int) 21,
		'title' => 'Mapping Seismic Hazard of Eastern Himalaya',
		'description' => '<h3>Why in News</h3>
<p>Recently, scientists have found the <strong>first geological evidence of an earthquake on the border of Assam and Arunachal Pradesh,</strong> documented as the <strong>Sadiya earthquake in history.</strong> This finding could contribute to a seismic hazard map of the eastern Himalaya, which can facilitate construction and planning in the region.</p>
<ul style="list-style-type: square;">
<li>This site is near the <strong>Tuting-Tidding Suture Zone-</strong> a major part of the Eastern Himalaya, where the Himalaya takes a sharp southward bend and connects with the Indo-Burma Range.</li>
</ul>
<h3>Key Points</h3>
<ul style="list-style-type: square;">
<li><strong>About:</strong> <br />
<ul style="list-style-type: circle;">
<li>Scientists from <strong>Wadia Institute of <a href="/daily-updates/daily-news-analysis/tectonically-active-zone-of-himalayas" target="_blank" rel="noopener">Himalayan Geology</a> (WIHG)</strong> carried out a mega trench excavation at <strong>Himebasti village, Arunachal Pradesh</strong> where the most recent event records the imprints of the<strong> 1697 Sadiya earthquake</strong> and analysed it with modern geological techniques.<br />
<ul style="list-style-type: disc;">
<li>WIHG is an<strong> autonomous institute</strong> under the Department of Science and Technology (DST), Government of India.</li>
</ul>
</li>
<li>Scientists found large tree trunks embedded in the<strong> youngest flood deposits at the exit of the Subansiri River</strong> (Sadiya town is located roughly 145 km southeast of Subansiri river), suggesting the <strong>post-seismic aggradation of the river</strong> following an array of<strong> aftershocks</strong> till six months.<br />
<ul style="list-style-type: disc;">
<li><strong>Aggradation</strong> is the term used in geology for the increase in land elevation due to deposition of sediment.</li>
<li><strong>Aftershocks</strong> are earthquakes that follow the largest shock of an earthquake sequence. They are smaller than the mainshock and within 1-2 rupture lengths distance from the mainshock.</li>
</ul>
</li>
</ul>
</li>
<li><strong>Significance:</strong> <br />
<ul style="list-style-type: circle;">
<li>Studying the past earthquakes help to <strong>determine the seismic potential</strong> of the region. This helps in mapping the earthquake hazard of the region and enables syncing the development activities accordingly.</li>
<li>Arunachal Pradesh, being near the <a href="/daily-updates/daily-news-analysis/india-china-conflict" target="_blank" rel="noopener"><strong>Indo-China Border</strong></a>, and sometimes centre of dispute regarding its ownership, is strategically important. <br />
<ul style="list-style-type: disc;">
<li>A number of development initiatives like constructing roads, bridges and hydropower projects are being undertaken, therefore there is an urgent need for understanding the pattern of seismicity in this region.</li>
</ul>
</li>
</ul>
</li>
<li><strong>Seismic Hazard Map of India:</strong><br />
<ul style="list-style-type: circle;">
<li>India is one of the highly earthquake affected countries<strong> because of the presence of tectonically active young fold mountains, Himalayas.</strong></li>
<li>India has been divided into <strong>four seismic zones (II, III, IV, and V)</strong> based on scientific inputs relating to seismicity, earthquakes occurred in the past and tectonic setup of the region.<br />
<ul style="list-style-type: disc;">
<li>Previously, earthquake zones were divided into five zones with respect to the severity of the earthquakes but the <strong><a href="/daily-updates/daily-news-analysis/bureau-of-indian-standards-bis-act-2016" target="_blank" rel="noopener">Bureau of Indian Standards</a> (BIS)</strong> grouped the country into four seismic zones by unifying the first two zones.</li>
<li>BIS is the official agency for publishing the seismic hazard maps and codes.</li>
</ul>
</li>
</ul>
</li>
</ul>
<p><a href="http://www.drishtiias.com/images/uploads/1612859443_image5.png" target="_blank" rel="noopener"><img class="content-img" src="http://www.drishtiias.com/images/uploads/1612859443_image5.png" style="display: block; margin-left: auto; margin-right: auto;" width="500" caption="false" /></a></p>
<ul style="list-style-type: square;">
<li><strong>Seismic Zone II:</strong><br />
<ul style="list-style-type: circle;">
<li><strong>Area with minor damage earthquakes</strong> corresponding to intensities V to VI of MM scale (MM-Modified Mercalli Intensity scale).</li>
</ul>
</li>
<li><strong>Seismic Zone III:</strong><br />
<ul style="list-style-type: circle;">
<li><strong>Moderate damage</strong> corresponding to intensity VII of MM scale.</li>
</ul>
</li>
<li><strong>Seismic Zone IV:</strong><br />
<ul style="list-style-type: circle;">
<li><strong>Major damage</strong> corresponding to intensity VII and higher of MM scale.</li>
</ul>
</li>
<li><strong>Seismic Zone V:</strong><br />
<ul style="list-style-type: circle;">
<li>Area determined by pro seismically of certain major fault systems and is seismically the most active region.</li>
<li><strong>Earthquake zone V is the most vulnerable to earthquakes,</strong> where historically some of the country&rsquo;s most powerful shocks have occurred.</li>
<li>Earthquakes with magnitudes in excess of 7.0 have occured in these areas, and have had intensities <strong>higher than IX.</strong></li>
</ul>
</li>
<li><strong>Seismic Waves, Richter Scale and Mercalli scale:</strong> <br />
<ul style="list-style-type: circle;">
<li>Seismic waves are the vibrations from earthquakes that travel through the Earth and are recorded on instruments called <strong>seismographs.</strong><br />
<ul style="list-style-type: disc;">
<li>Seismographs record a zigzag trace that shows the varying amplitude of ground oscillations beneath the instrument.</li>
</ul>
</li>
<li>The earthquake events are scaled either according to the magnitude or intensity of the shock.<br />
<ul style="list-style-type: disc;">
<li>The magnitude scale is known as the<strong> Richter scale.</strong> The magnitude relates to the energy released during the earthquake which is expressed in absolute numbers, 0-10.</li>
<li>The intensity scale or <strong>Mercalli scale</strong> takes into account the visible damage caused by the event. The range of intensity scale is from 1-12.</li>
</ul>
</li>
</ul>
</li>
</ul>
<p><a href="https://pib.gov.in/PressReleseDetailm.aspx?PRID=1696073#:~:text=Scientists%20have%20found%20the%20first,the%20town%20in%201697%20CE." target="_blank" rel="noopener"><strong>Source:PIB</strong></a></p>',
		'posturl' => 'mapping-seismic-hazard-of-eastern-himalaya',
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		'tag' => 'Important Geophysical Phenomena',
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	(int) 4 => object(Cake\ORM\Entity) {

		'article_id' => (int) 7637,
		'category_id' => (int) 26,
		'title' => 'Pacific Ring of Fire',
		'description' => '<ul style="list-style-type: square;">
<li>The <strong>Ring of Fire,</strong> also referred to as the<strong> Circum-Pacific Belt,</strong> is a path along the Pacific Ocean characterized by active volcanoes and frequent earthquakes. <br />
<ul style="list-style-type: circle;">
<li>It is largely a result of<a href="/to-the-points/paper1/tectonic-plates" target="_blank" rel="noopener"><strong> Plate Tectonics</strong></a> where <strong>massive Pacific Plate</strong> interacts with less-dense plates surrounding it.</li>
</ul>
</li>
<li>The<strong> majority of Earth&rsquo;s volcanic eruptions and earthquakes</strong> take place along the Ring of Fire.<br />
<ul style="list-style-type: circle;">
<li>The next most seismically active region (5-6% of earthquakes) is the <strong>Alpide belt</strong> (extends from Mediterranean region, eastward through Turkey, Iran, and northern India.</li>
</ul>
</li>
</ul>
<h3>Geographical Stretch of Ring of Fire</h3>
<ul style="list-style-type: square;">
<li>The Ring of Fire is stretched to approximately <strong>40,000 kilometers</strong> (24,900 miles) tracing boundaries between several tectonic plates including the <strong>Pacific, Juan de Fuca, Cocos, Indian-Australian, Nazca, North American, </strong>and <strong>Philippine Plates.</strong></li>
<li>The chain runs up along the<strong> western coast of South and North America,</strong> crosses over the <strong>Aleutian Islands in Alaska,</strong> runs down the <strong>eastern coast of Asia past New Zealand</strong> and into the <strong>northern coast of Antarctica.</strong></li>
<li>Bolivia, Chile, Ecuador, Peru, Costa Rica, Guatemala, Mexico, United States, Canada, Russia, Japan, Philippines, Australia, Papua New Guinea, Indonesia, New Zealand, and Antarctica are some of the<strong> important places located in the ring of the fire.</strong></li>
</ul>
<p><a href="http://www.drishtiias.com/images/uploads/1612769443_image1.jpg" target="_blank" rel="noopener"><strong><img class="content-img" src="http://www.drishtiias.com/images/uploads/1612769443_image1.jpg" style="display: block; margin-left: auto; margin-right: auto;" width="650" caption="false" /></strong></a></p>
<h3>Features of Ring of Fire</h3>
<p><strong>Active volcanoes:</strong></p>
<ul style="list-style-type: square;">
<li>The Ring of Fire is home to<strong> more than 450 active and dormant volcanoes</strong> (75% of Earth&rsquo;s total volcanoes) forming a semicircle or horse shoe around the rim of the Pacific Ocean.</li>
<li>Most of the active volcanoes on the Ring of Fire are found on its<strong> western edge,</strong> from Russia to New Zealand. <br />
<ul style="list-style-type: circle;">
<li>Major volcanic events that have occurred within the Ring of Fire since 1800 including the eruptions of Mount Tambora, Indonesia (1815), Mount Ruiz, Columbia (1985), and Mount Pinatubo, Philippines (1991).</li>
</ul>
</li>
<li>The <strong>Mount Tambora of Indonesia,</strong> which erupted in 1815 was the largest volcanic eruption in recorded history.<br />
<ul style="list-style-type: circle;">
<li>It is now 2,851 metres (9,354 feet) high after losing much of its top in the 1815 eruption.</li>
</ul>
</li>
<li><strong>Mount Ruapehu in New Zealand</strong> is one of the more active volcanoes in the Ring of Fire, with<strong> yearly minor eruptions,</strong> and major eruptions occurring about every 50 years.</li>
<li><strong>Krakatoa, an island volcano,</strong> erupts less often than Mount Ruapehu, but<strong> much more spectacularly.</strong> <br />
<ul style="list-style-type: circle;">
<li>An infamous eruption in <strong>1883</strong> destroyed the entire island, sending volcanic gas, volcanic ash, and rocks as high as <strong>80 kilometers (50 miles) in the air.</strong></li>
</ul>
</li>
<li><strong>Mount Fuji,</strong> Japan&rsquo;s tallest and most famous mountain, is an active volcano in the Ring of Fire.<br />
<ul style="list-style-type: circle;">
<li>Mount Fuji sits at a<strong> &ldquo;triple junction&rdquo;,</strong> where three tectonic plates (the<strong> Amur Plate, Okhotsk Plate,</strong> and <strong>Philippine Plate</strong>) interact.</li>
</ul>
</li>
<li>The Ring of Fire&rsquo;s <strong>eastern half</strong> also has a number of active volcanic areas, including the<strong> Aleutian Islands, the Cascade Mountains</strong> in the western U.S., the <strong>Trans-Mexican Volcanic Belt,</strong> and the<strong> Andes Mountains.</strong></li>
<li><strong>Mount St. Helens,</strong> in the U.S. state of Washington, is an<strong> active volcano in the Cascade Mountain.</strong><br />
<ul style="list-style-type: circle;">
<li>It lies on a particularly weak section of crust, which makes it more prone to eruptions. Its historic <strong>1980 eruption lasted 9 hours</strong> and covered nearby areas in tons of volcanic ash.</li>
</ul>
</li>
<li><strong>Popocat&eacute;petl</strong> is one of the most dangerous volcanoes in the Ring of Fire. <br />
<ul style="list-style-type: circle;">
<li>The mountain is one of Mexico&rsquo;s most active volcanoes, with<strong> 15 recorded eruptions since 1519.</strong></li>
</ul>
</li>
</ul>
<p><strong>Earthquakes</strong></p>
<ul style="list-style-type: square;">
<li><strong>90%</strong> of earthquakes occur along its path, including the planet&rsquo;s most violent and dramatic seismic events.</li>
<li>The Ring of Fire has been the setting for the <strong>most devastating earthquakes</strong> in recorded history, including the Chile earthquake of 1960 and 2010, the Alaska earthquake of 1964, and the Japan earthquake of 2011 as well as the earthquake that produced the devastating Indian Ocean tsunami of 2004.<br />
<ul style="list-style-type: circle;">
<li>The<strong> Valdivia Earthquake of Chile,</strong> occurred in 1960, was the<strong> strongest</strong> recorded earthquake at <strong>9.5 out of 10</strong> on the Richter scale.</li>
<li>The Chile Earthquake is closely followed by the <strong>Great Alaska Earthquake, 1964</strong> (magnitude <strong>9.2</strong>)</li>
<li>The<strong> Northern Sumatra earthquake</strong> (the <strong>Indian Ocean Tsunami</strong>), December 26, 2004 (magnitude 9.1)</li>
<li>The<strong> Earthquake on the East Coast of Honshu,</strong> Japan on March 11, 2011 (magnitude <strong>9.0</strong>) which led to a tsunami and ultimately the <strong>nuclear disaster at Fukushima.</strong></li>
</ul>
</li>
</ul>
<p><strong>Island Arcs</strong></p>
<ul style="list-style-type: square;">
<li>They are long, curved chains of<strong> oceanic islands</strong> associated with <strong>intense volcanic and seismic activity and orogenic</strong> (mountain-building) processes.</li>
<li>An island arc typically has a<strong> land mass or a partially enclosed, unusually shallow sea</strong> on its concave side.</li>
<li>Along the convex side there almost invariably exists a long, <strong>narrow deep-sea trench.</strong></li>
<li>The greatest ocean depths are found in these depressions of the seafloor, as in the case of the <strong>Mariana (deepest trench in the world) and Tonga trenches.</strong><br />
<ul style="list-style-type: circle;">
<li>Prime examples of this form of geologic feature include the <strong>Aleutian-Alaska Arc</strong> and the<strong> Kuril-Kamchatka Arc.</strong></li>
</ul>
</li>
</ul>
<p><strong>Trenches</strong></p>
<ul style="list-style-type: square;">
<li>Ocean trenches are steep depressions in the deepest parts of the ocean where an old ocean crust from one tectonic plate is pushed beneath another plate, raising mountains, causing earthquakes, and forming volcanoes on the seafloor and on land.</li>
<li>The ring of fire is home to the<strong> deepest ocean trench,</strong> called the<strong> Mariana Trench.</strong> It is a 7-mile-deep trench.<br />
<ul style="list-style-type: circle;">
<li>Other trenches in the region are: Philippine Trench, Challenger trench, Kuril- Kamchatka Trench, Peru&ndash;Chile Trench and Tonga Trench.</li>
</ul>
</li>
<li>The presence of oceanic trenches indicates tectonic instability extending into the mantle of the earth. <br />
<ul style="list-style-type: circle;">
<li>The trench is probably the oldest part of the structure, is the seat of normal-depth earthquake.</li>
</ul>
</li>
</ul>
<h3>Cause of Frequent Earthquakes and Volcanism</h3>
<ul style="list-style-type: square;">
<li>The Ring of Fire is the result of tectonic plates which are huge slabs of the Earth&rsquo;s crust, fitting together like pieces of a puzzle. <br />
<ul style="list-style-type: circle;">
<li>Sometimes these moving plates collide, or move apart, or slide next to each other, which lead to the formation of <strong>convergent, divergent or transform boundaries</strong> (respectively).</li>
</ul>
</li>
<li>This constant <strong>collision, diversion or sliding-past-each-other movement</strong> of tectonic plates results in <strong>deep ocean trenches, volcanic eruptions, and earthquake epicenters</strong> along the boundaries where the plates meet, called<strong> fault lines.</strong><br />
<ul style="list-style-type: circle;">
<li>Volcanoes are created through the process of <strong>subduction</strong> and most of the planet's <strong>subduction zones</strong> happen to be located in the Ring of Fire.</li>
</ul>
</li>
<li>A significant&nbsp;<strong>exception</strong> is the border between the<strong> Pacific and North American Plates.</strong><br />
<ul style="list-style-type: circle;">
<li>This stretch of the Ring of Fire is a<strong> transform boundary,</strong> where plates move sideways past one another.</li>
<li>This type of boundary <strong>generates a large number of earthquakes</strong> as tension in Earth&rsquo;s crust builds up and is released.</li>
</ul>
</li>
</ul>
<div class="border-bg">
<p><strong>Subduction:</strong></p>
<ul style="list-style-type: square;">
<li>Subduction happens when tectonic plates shift, and one plate is pushed under another. This movement of the ocean floor produces a <strong>"mineral transmutation",</strong> which leads to the melting and solidification of magma i.e., the <strong>formation of volcanoes.</strong> <br />
<ul style="list-style-type: circle;">
<li>In other words, when a "downgoing" oceanic plate is pushed into a hotter mantle plate, it heats up, volatile elements mix, and this produces the magma. The magma then rises up through the overlying plate and spurts out at the surface.</li>
</ul>
</li>
<li>A subduction zone is the <strong>biggest crash scene on Earth.</strong> These <strong>boundaries mark the collision</strong> between two tectonic plates.</li>
<li>When two tectonic plates meet at a subduction zone, one bends and slides underneath the other, curving down into the mantle, the hotter layer under the crust.</li>
</ul>
<p><a href="http://www.drishtiias.com/images/uploads/1612769526_image2.png" target="_blank" rel="noopener"><img class="content-img" src="http://www.drishtiias.com/images/uploads/1612769526_image2.png" style="display: block; margin-left: auto; margin-right: auto;" width="500" caption="false" /></a></p>
</div>
<h3>Source of Geothermal Resources</h3>
<ul style="list-style-type: square;">
<li>World&rsquo;s <strong>largest geothermal energy resources (more than 40%)</strong> are stored in the Pacific Ring of Fire.</li>
<li>Geothermal resources are highly<strong> associated with the active plate boundary</strong> (divergent or convergent plate type) where volcanism or frequent earthquakes have occurred.<br />
<ul style="list-style-type: circle;">
<li>The region is tectonically a very much active region, and as a result, it has <strong>stored a lot of heat which can be used as geothermal resources.</strong></li>
</ul>
</li>
<li>Around <strong>13 GW</strong> (till 2015) power generations had been installed on the basis of geothermal resources in the world where more than<strong> 6 GW</strong> have been found in the ring of fire region.</li>
<li>The geothermal energy resources can be utilized both for<strong> electricity generation</strong> and <strong>direct uses.</strong></li>
<li>Roughly estimated <strong>more than 110 GW electricity generation capabilities</strong> of geothermal resources can be found in this region.</li>
</ul>
<h3>Recent Research</h3>
<ul style="list-style-type: square;">
<li>The <strong>Pacific Plate,</strong> which drives much of the tectonic activity in the Ring of Fire, is <strong>cooling off.</strong></li>
<li>Scientists have discovered that the <strong>youngest parts of the Pacific Plate</strong> (about 2 million years old) are cooling off and <strong>contracting at a faster rate</strong> than older parts of the plate (about 100 million years old).</li>
<li>The younger parts of the plate are<strong> found in its northern and western parts;</strong> the most active parts of the Ring of Fire.</li>
</ul>',
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	(int) 5 => object(Cake\ORM\Entity) {

		'article_id' => (int) 7587,
		'category_id' => (int) 26,
		'title' => 'Tectonic Plates',
		'description' => '<h3>Tectonic Plates</h3>
<ul style="list-style-type: square;">
<li>A tectonic plate (also called lithospheric plate) is a massive, irregularly-shaped slab of solid rock, generally composed of both continental and oceanic lithosphere.<br />
<ul style="list-style-type: circle;">
<li>The lithosphere includes the crust and top mantle with its thickness range varying between<strong> 5-100 km</strong> in oceanic parts and about <strong>200 km</strong> in the continental areas.</li>
<li>The concept of Tectonic Plates was first introduced in 1967.</li>
</ul>
</li>
<li>A tectonic plate may be a <strong>continental plate</strong> or an <strong>oceanic plate,</strong> depending on which of the two occupies the larger portion of the plate.<br />
<ul style="list-style-type: circle;">
<li>The<strong> Pacific plate</strong> is largely an oceanic plate whereas the <strong>Eurasian plate</strong> is a continental plate.</li>
</ul>
</li>
</ul>
<h3>The Major and Minor Plates</h3>
<p>The Earth&rsquo;s lithosphere is divided into seven major and some minor plates.</p>
<ul style="list-style-type: square;">
<li>Young<strong> Fold Mountain ridges, oceanic trenches,</strong> and/or <strong>transform faults</strong> surround the<strong> major plates.</strong> These include: <br />
<ul style="list-style-type: circle;">
<li>The <strong>Antarctic (and the surrounding oceanic) plate</strong></li>
<li>The <strong>North American plate</strong> (with western Atlantic floor separated from the South American plate along the Caribbean islands)</li>
<li>The <strong>South American plate</strong> (with western Atlantic floor separated from the North American plate along the Caribbean islands)</li>
<li>The<strong> Pacific plate</strong></li>
<li>The<strong> India-Australia-New Zealand plate</strong></li>
<li>The <strong>Africa with the eastern Atlantic floor plate</strong></li>
<li><strong>Eurasia and the adjacent oceanic plate</strong></li>
</ul>
</li>
<li>Some important<strong> minor plates</strong> include:<br />
<ul style="list-style-type: circle;">
<li><strong>Cocos plate:</strong> Between Central America and Pacific plate</li>
<li><strong>Nazca plate:</strong> Between South America and Pacific plate</li>
<li><strong>Arabian plate:</strong> Mostly the Saudi Arabian landmass</li>
<li><strong>Philippine plate:</strong> Between the Asiatic and Pacific plate</li>
<li><strong>Caroline plate:</strong> Between the Philippine and Indian plate (North of New Guinea)</li>
<li><strong>Fuji plate:</strong> North-east of Australia</li>
<li><strong>Juan De Fuca plate:</strong> South-East of North American Plate</li>
</ul>
</li>
</ul>
<div class="border-bg">
<ul style="list-style-type: square;">
<li><strong>Mountain Ridge:</strong> A mountain ridge refers to the chain of mountains or hills that form a continuous elevated crest for some distance.</li>
<li><strong>Ocean trenches</strong> are long, narrow depressions on the seafloor. <br />
<ul style="list-style-type: circle;">
<li>These are the deepest parts of the ocean and some of the deepest natural spots on Earth.</li>
<li>They are found in every ocean basin on the planet and the deepest ocean trenches ring the Pacific called the &ldquo;Ring of Fire''.</li>
</ul>
</li>
<li>A<strong> transform fault,</strong> in geology and oceanography is a type of fault in which two tectonic plates slide past one another.</li>
</ul>
<p><strong>The Indian Plate:</strong></p>
<ul style="list-style-type: square;">
<li>The Indian plate includes <strong>Peninsular India and the Australian continental portions.</strong></li>
<li>In the east, it extends through <strong>Rakim Yoma Mountains</strong> of Myanmar towards the <strong>island arc along the Java Trench.</strong></li>
<li>The Western margin follows <strong>Kirthar Mountain of Pakistan.</strong><br />
<ul style="list-style-type: circle;">
<li>It further extends along the <strong>Makrana coast of Balochistan</strong> and joins the spreading site from the Red Sea rift southeastward along the <strong>Chagos Archipelago.</strong></li>
</ul>
</li>
<li>The boundary between India and the Antarctic plate is also marked by an oceanic ridge (divergent boundary) running in roughly West to East direction and merging into the spreading site, a little south of New Zealand.</li>
</ul>
<p><strong>Asthenosphere:</strong></p>
<ul style="list-style-type: square;">
<li>It is the zone of Earth&rsquo;s mantle that lies just beneath the lithosphere and is believed to be much hotter and more fluid than the lithosphere.</li>
<li>The asthenosphere extends from about 100 km (60 miles) to about 700 km (450 miles) below Earth&rsquo;s surface.</li>
</ul>
</div>
<h3>Movement of Plates</h3>
<p>The tectonic plates are not fixed but constantly move horizontally over the <strong>Asthenosphere</strong> as rigid units.</p>
<ul style="list-style-type: square;">
<li>Sometimes these plates collide, move apart, or slide next to each other which leads to <strong>Earthquakes or Volcanic Eruptions.</strong></li>
<li><strong>Rates of Movement of Tectonic Plates:</strong> The rates of movement of the tectonic plates vary considerably. <br />
<ul style="list-style-type: circle;">
<li>The <strong>Arctic Ridge</strong> has the slowest rate (less than 2.5 cm/yr), and the<strong> East Pacific Rise,</strong> in the South Pacific (about 3,400 km west of Chile) has the fastest rate (more than 15 cm/yr).</li>
</ul>
</li>
<li><strong>Force for the Movement of Tectonic Plates:</strong> The mobile rock beneath the rigid plates is believed to be moving in a circular manner. <br />
<ul style="list-style-type: circle;">
<li>The heated material rises to the surface, spreads and begins to cool, and then sinks back into deeper depths.</li>
<li>This<strong> slow movement of hot, softened mantle</strong> that lies below these rigid plates is the driving force behind the plate movement.</li>
</ul>
</li>
</ul>
<p><a href="http://www.drishtiias.com/images/uploads/1612171866_image2.png" target="_blank" rel="noopener"><img class="content-img" src="http://www.drishtiias.com/images/uploads/1612171866_image2.png" style="display: block; margin-left: auto; margin-right: auto;" width="350" caption="false" /></a></p>
<p><strong>Subduction</strong></p>
<ul style="list-style-type: square;">
<li>It happens when tectonic plates shift, and one plate is pushed under another.</li>
<li>This movement of the ocean floor produces a<strong> "mineral transmutation",</strong> which leads to the melting and solidification of magma i.e., the <strong>formation of volcanoes.</strong> <br />
<ul style="list-style-type: circle;">
<li>In other words, when a "downgoing" oceanic plate is pushed into a hotter mantle plate, it heats up, volatile elements mix, and this produces the magma.</li>
<li>The magma then rises up through the overlying plate and spurts out at the surface.</li>
</ul>
</li>
</ul>
<p><a href="http://www.drishtiias.com/images/uploads/1612171896_image1.png" target="_blank" rel="noopener"><img class="content-img" src="http://www.drishtiias.com/images/uploads/1612171896_image1.png" style="display: block; margin-left: auto; margin-right: auto;" width="450" caption="false" /></a></p>
<h3>Boundaries of Plates</h3>
<p>The movement of the tectonic plates creates three types of tectonic boundaries:</p>
<ol>
<li><strong>Convergent,</strong> where plates move into one another.</li>
<li><strong>Divergent,</strong> where plates move apart.</li>
<li><strong>Transform,</strong> where plates move sideways in relation to each other.</li>
</ol>
<p><strong>Convergent Boundaries</strong></p>
<ul style="list-style-type: square;">
<li>A convergent plate boundary is formed when tectonic plates crash into each other. They are also known as<strong> destructive boundaries.</strong></li>
<li>These boundaries are often <strong>subduction zones,</strong> where the heavier plate slips under the lighter plate, creating a deep trench. <br />
<ul style="list-style-type: circle;">
<li>This subduction changes the dense mantle material into buoyant magma, which rises through the crust to the Earth&rsquo;s surface.</li>
<li>Over millions of years, the rising magma has been creating a series of active volcanoes known as a <strong>volcanic arc.</strong></li>
</ul>
</li>
<li>Other than Subduction Zones, convergent plate boundaries also lead to mountain building and the formation of <strong>island arcs (Festoons).</strong> <br />
<ul style="list-style-type: circle;">
<li>If both the convergent plates are oceanic, the volcanoes form a curved line of islands, known as an<strong> island arc,</strong> that is <strong>parallel to the trench.</strong></li>
</ul>
</li>
<li>There are three ways in which convergence can occur: <br />
<ul style="list-style-type: circle;">
<li>between an <strong>oceanic and continental</strong> plate</li>
<li>between<strong> two oceanic</strong> plate</li>
<li>between <strong>two continental</strong> plates.<br />
<ul style="list-style-type: disc;">
<li>When continental and oceanic plates collide, the thinner and more dense oceanic plate is overridden by the thicker and less dense continental plate.</li>
</ul>
</li>
</ul>
</li>
<li><strong>Examples:</strong> <br />
<ul style="list-style-type: circle;">
<li>The <strong>Washington-Oregon coastline</strong> of the United States is an example of <strong>oceanic-continental convergent</strong> plate boundary. <br />
<ul style="list-style-type: disc;">
<li>Here, the <strong>Juan de Fuca oceanic plate</strong> is subducted beneath the <strong>North American continental plate.</strong></li>
</ul>
</li>
<li>An example of the<strong> oceanic-oceanic convergence</strong> is the <strong>Mariana Trench,</strong> the deepest point on Earth. <br />
<ul style="list-style-type: disc;">
<li>The <strong>mighty Pacific plate</strong> subducts beneath the <strong>smaller, less-dense Philippine plate.</strong></li>
</ul>
</li>
<li>The <strong>Himalayan Mountain Range</strong> is the best active example of <strong>continental convergent plate boundaries.</strong> <br />
<ul style="list-style-type: disc;">
<li>India and Asia crashed about 55 million years ago, slowly giving rise to the Himalayas, the highest mountain system on Earth.</li>
<li>Here, the<strong> Indian and Eurasian plates are currently in collision.</strong></li>
</ul>
</li>
</ul>
</li>
</ul>
<div class="border-bg">
<p><strong>Subduction Zones</strong></p>
<ul style="list-style-type: square;">
<li>A subduction zone is the biggest crash scene on Earth. These boundaries mark the collision between two tectonic plates.</li>
<li>When two tectonic plates meet at a subduction zone, one bends and slides underneath the other, curving down into the mantle, the hotter layer under the crust.</li>
</ul>
</div>
<p><strong>Divergent Boundaries</strong></p>
<ul style="list-style-type: square;">
<li>A divergent boundary is formed by tectonic plates pulling apart from each other. They are known as <strong>constructive boundaries.</strong></li>
<li>Divergent boundaries are the site of <strong>seafloor spreading</strong> and<strong> rift valleys.</strong></li>
<li>At divergent boundaries<strong> in the oceans,</strong> magma from deep in the Earth's mantle rises toward the surface and pushes apart two or more plates. Mountains and volcanoes rise along the seam. The process renews the ocean floor and widens the giant basins. <br />
<ul style="list-style-type: circle;">
<li>The best-known example of divergent boundaries is the <strong>Mid-Atlantic Ridge</strong> where the <strong>American Plates</strong> are <strong>separated from the Eurasian and African Plates.</strong> <br />
<ul style="list-style-type: disc;">
<li>This single mid-ocean ridge system connects the world's oceans, making the ridge the longest mountain range in the world (10,000 miles).</li>
</ul>
</li>
</ul>
</li>
<li><strong>On land,</strong> giant troughs such as the <strong>Great Rift Valley in Africa</strong> form where plates are tugged apart. <br />
<ul style="list-style-type: circle;">
<li>If the plates there continue to diverge, millions of years from now eastern Africa will split from the continent to form a new landmass.</li>
<li>A mid-ocean ridge would then mark the boundary between the plates.</li>
</ul>
</li>
</ul>
<div class="border-bg">
<p><strong>Seafloor Spreading</strong></p>
<ul style="list-style-type: square;">
<li>Seafloor spreading is the process of <strong>magma welling up in the rift</strong> as the old crust pulls itself in opposite directions.</li>
<li>Cold seawater cools the magma, creating a new crust.</li>
<li>The upward movement and eventual cooling of this magma has created high ridges on the ocean floor over millions of years.</li>
<li>The <strong>East Pacific Rise</strong> is a site of <strong>major seafloor spreading</strong> in the <strong>Ring of Fire.</strong> <br />
<ul style="list-style-type: circle;">
<li>It is located on the divergent boundary of the<strong> Pacific Plate, the Cocos Plate</strong> (west of Central America),<strong> the Nazca Plate</strong> (west of South America), the <strong>North-American Plate and the Antarctic Plate.</strong></li>
</ul>
</li>
</ul>
<p><strong>Rift Valleys</strong></p>
<ul style="list-style-type: square;">
<li>A rift valley is a <strong>lowland region</strong> that forms where Earth&rsquo;s tectonic plates move apart, or rift.</li>
<li>Rift valleys are<strong> found both on land and at the bottom of the ocean</strong> and are created by the process of<strong> seafloor spreading.</strong></li>
<li>Rift valleys differ from river valleys and glacial valleys in that they are <strong>created by tectonic activity</strong> and not the process of erosion.</li>
<li>The Great Rift Valley System which stretches from the <strong>Middle East in the north to Mozambique in the south</strong> is a<strong> geologically active area.</strong>
<ul style="list-style-type: circle;">
<li>It features<strong> volcanoes,</strong> hot springs, geysers, and<strong> frequent earthquakes.</strong></li>
</ul>
</li>
</ul>
</div>
<p><strong>Transform Boundaries</strong></p>
<ul style="list-style-type: square;">
<li>A transform boundary is formed as<strong> tectonic plates slide horizontally past each other</strong> but parts of these plates get stuck at the places where they touch. <br />
<ul style="list-style-type: circle;">
<li>These boundaries are <strong>conservative</strong> because plate interaction occurs without creating or destroying crust. <br />
<ul style="list-style-type: disc;">
<li>Hence, they don't produce spectacular features like mountains or oceans, but the halting motion <strong>often triggers large earthquakes,</strong> such as the<strong> 1906 earthquake</strong> that devastated <strong>San Francisco.</strong></li>
</ul>
</li>
</ul>
</li>
<li>In these areas of contact, stress is built which causes the rocks to break or slip, suddenly lurching the plates forward and causing earthquakes. <br />
<ul style="list-style-type: circle;">
<li>These areas of breakage or slippage are called <strong>faults.</strong> The majority of Earth&rsquo;s faults can be found along transform boundariesin<strong> the Ring of Fire.</strong></li>
</ul>
</li>
<li>The <strong>San Andreas Fault in California</strong> is an example of a transform boundary, where the Pacific Plate moves northward past the North American Plate. <br />
<ul style="list-style-type: circle;">
<li>It is one of the most active faults on the Ring of Fire.</li>
</ul>
</li>
</ul>
<p><a href="http://www.drishtiias.com/images/uploads/1612171936_image3.png" target="_blank" rel="noopener"><img class="content-img" src="http://www.drishtiias.com/images/uploads/1612171936_image3.png" style="display: block; margin-left: auto; margin-right: auto;" caption="false" width="605" height="399" /></a></p>
<div class="border-bg">
<p><strong>Hotspots</strong></p>
<ul style="list-style-type: square;">
<li>Most of the volcanic activities are concentrated along or adjacent to plate boundaries, but there are some<strong> important exceptions</strong> in which this activity occurs within plates, called the<strong> Hotspots.</strong></li>
<li>Hotspots exist over the<strong> Mantle Plumes.</strong> <br />
<ul style="list-style-type: circle;">
<li>A mantle plume is an area <strong>under the crust of Earth, where magma is hotter than surrounding magma.</strong></li>
<li>Heat from this extra hot magma causes melting and thinning of the rocky crust, which leads to widespread volcanic activity on Earth&rsquo;s surface above the plume.</li>
</ul>
</li>
<li>The hotspots are<strong> stationary,</strong> unlike the tectonic plates where they are located.</li>
<li>There are about<strong> 40 to 50 hot spots estimated</strong> to be around the world.</li>
<li>Major hot spots include : <br />
<ul style="list-style-type: circle;">
<li>The<strong> Iceland hotspot,</strong> under the island of Iceland in the North Atlantic.</li>
<li>The <strong>R&eacute;union hot spot,</strong> under the island of R&eacute;union in the Indian Ocean.</li>
<li>The <strong>Afar hotspot,</strong> located under northeastern Ethiopia.</li>
</ul>
</li>
</ul>
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	(int) 6 => object(Cake\ORM\Entity) {

		'article_id' => (int) 7482,
		'category_id' => (int) 26,
		'title' => 'El Nino and La Nina',
		'description' => '<ul style="list-style-type: square;">
<li><strong>El Nino and La Nina</strong> are complex weather patterns resulting from variations in ocean temperatures in the Equatorial Pacific Region. They are opposite phases of what is known as the<strong> El Nino-Southern Oscillation (ENSO)</strong> cycle. <br />
<ul style="list-style-type: circle;">
<li>The ENSO cycle describes the fluctuations in temperature between the ocean and atmosphere in the east-central Equatorial Pacific.</li>
<li>El Nino and La Nina episodes typically last nine to 12 months, but some prolonged events may last for years.</li>
</ul>
</li>
<li><strong>El Nino</strong> is a climate pattern that describes the<strong> unusual warming of surface waters</strong> in the <strong>eastern tropical Pacific Ocean.</strong> <br />
<ul style="list-style-type: circle;">
<li>It is the &ldquo;warm phase&rdquo; of a larger phenomenon called the El Nino-Southern Oscillation (ENSO).</li>
<li>It occurs more frequently than La Nina.</li>
</ul>
</li>
<li><strong>La Nina, the &ldquo;cool phase&rdquo;</strong> of ENSO, is a pattern that describes the <strong>unusual cooling</strong> of the tropical eastern Pacific. <br />
<ul style="list-style-type: circle;">
<li>La Nina events may last between <strong>one and three years, unlike El Nino,</strong> which usually lasts no more than a year.</li>
<li><strong>Both phenomena tend to peak during the Northern Hemisphere winter.</strong></li>
</ul>
</li>
</ul>
<h3>El Nino</h3>
<ul style="list-style-type: square;">
<li>El Nino was<strong> first recognized by Peruvian fishermen</strong> off the coast of Peru as the appearance of unusually warm water. <br />
<ul style="list-style-type: circle;">
<li>The Spanish immigrants called it <strong>El Nino, meaning &ldquo;the little boy&rdquo;</strong> in Spanish.</li>
</ul>
</li>
<li>El Nino soon came to describe irregular and intense climate changes rather than just the warming of coastal surface waters.</li>
<li>The El Nino event is<strong> not a regular cycle,</strong> they are not predictable and occur irregularly at two- to seven-year intervals. <br />
<ul style="list-style-type: circle;">
<li>The climatologists determined that El Nino occurs simultaneously with the Southern Oscillation. <br />
<ul style="list-style-type: disc;">
<li>The Southern Oscillation is a change in air pressure over the tropical Pacific Ocean.</li>
</ul>
</li>
</ul>
</li>
<li>When coastal waters become warmer in the eastern tropical Pacific (El Nino), the atmospheric pressure above the ocean decreases.<br />
<ul style="list-style-type: circle;">
<li>Climatologists define these linked phenomena as <strong>El Nino-Southern Oscillation (ENSO).</strong></li>
</ul>
</li>
</ul>
<p><strong>Monitoring El Nino and La Nina</strong></p>
<ul style="list-style-type: square;">
<li>Scientists, governments, and non-governmental organizations (NGOs) collect data about El Nino using a number of technologies such as<strong> scientific buoys.</strong><br />
<ul style="list-style-type: circle;">
<li>A buoy is a type of an <strong>object that floats in water</strong> and is used in the middle of the <strong>seas as locators or as warning points for the ships.</strong> They are generally bright (fluorescent) in colour.</li>
<li>These buoys measure ocean and air temperatures, currents, winds, and humidity.</li>
<li>The buoys transmit data daily to researchers and forecasters around the world enabling the scientists to more accurately predict El Nino and visualize its development and impact around the globe.</li>
</ul>
</li>
<li>The <strong>Oceanic Nino Index (ONI)</strong> is used to measure deviations from normal sea surface temperatures.<br />
<ul style="list-style-type: circle;">
<li>The intensity of El Nino events varies from weak temperature increases (about 4-5&deg; F) with only moderate local effects on weather and climate to very strong increases (14-18&deg; F) associated with worldwide climatic changes.</li>
</ul>
</li>
</ul>
<div class="border-bg">
<p><strong>Oceanic Nino Index (ONI)</strong></p>
<ul style="list-style-type: square;">
<li>The <strong>Oceanic Ni&ntilde;o Index (ONI),</strong> is a measure of the departure from normal sea surface temperature in the east-central Pacific Ocean, is the standard means by which each El Nino episode is determined, gauged, and forecast.</li>
</ul>
</div>
<p><strong>Impact of El Nino</strong></p>
<ul style="list-style-type: square;">
<li>In order to understand the concept of El Nino, it&rsquo;s important to be familiar with non-El Nino conditions in the Pacific Ocean. <br />
<ul style="list-style-type: circle;">
<li>Normally,<strong> strong trade winds blow westward</strong> across the tropical Pacific, the region of the Pacific Ocean located between the <strong>Tropic of Cancer and the Tropic of Capricorn. </strong></li>
</ul>
</li>
<li><strong>Impact on Ocean:</strong> El Nino also impacts ocean temperatures, the speed and strength of ocean currents, the health of coastal fisheries, and local weather from Australia to South America and beyond.</li>
<li><strong>Increased Rainfall:</strong> Convection above warmer surface waters brings increased precipitation. <br />
<ul style="list-style-type: circle;">
<li>Rainfall increases drastically in South America, contributing to coastal flooding and erosion.</li>
</ul>
</li>
<li><strong>Diseases caused by Floods and Droughts:</strong> Diseases thrive in communities devastated by natural hazards such as flood or drought. <br />
<ul style="list-style-type: circle;">
<li>El Nino-related flooding is associated with increases in cholera, dengue, and malaria in some parts of the world, while drought can lead to wildfires that create respiratory problems.</li>
</ul>
</li>
<li><strong>Positive impact:</strong> It can sometimes have a positive impact too, for example, El Nino reduces the instances of hurricanes in the Atlantic.</li>
<li><strong>In South America:</strong> As El Nino brings rain to South America, it brings droughts to Indonesia and Australia. <br />
<ul style="list-style-type: circle;">
<li>These droughts threaten the region&rsquo;s water supplies, as reservoirs dry and rivers carry less water. Agriculture, which depends on water for irrigation, is also threatened.</li>
</ul>
</li>
<li><strong>In Western Pacific:</strong> These winds<strong> push warm surface water</strong> towards the western Pacific, where it borders <strong>Asia and Australia.</strong><br />
<ul style="list-style-type: circle;">
<li>Due to the warm trade winds, the sea surface is normally about <strong>0.5 meter higher </strong>and<strong> 4-5&deg; F warmer in Indonesia than Ecuador.</strong></li>
<li>The westward movement of warmer waters causes<strong> cooler waters to rise up</strong> towards the surface on the coasts of<strong> Ecuador, Peru, and Chile.</strong> This process is known as <strong>upwelling.</strong> <br />
<ul style="list-style-type: disc;">
<li>Upwelling elevates cold, nutrient-rich water to the euphotic zone, the upper layer of the ocean.</li>
</ul>
</li>
</ul>
</li>
</ul>
<div class="border-bg">
<p><strong>Previous El Nino Events:</strong></p>
<ul style="list-style-type: square;">
<li>El Nino events of <strong>1982-83 and 1997-98</strong> were the <strong>most intense</strong> of the 20<sup>th</sup> century.</li>
<li>During the<strong> 1982-83</strong> event, sea surface temperatures in the eastern tropical Pacific were 9-18&deg; F above normal.</li>
<li>The El Nino event of <strong>1997-98</strong> was the first El Nino event to be<strong> scientifically monitored from beginning to end.</strong></li>
<li>The 1997-98 event produced drought conditions in Indonesia, Malaysia, and the Philippines. Peru and California experienced very heavy rains and severe flooding.</li>
<li>The Midwest experienced record-breaking warm temperatures during a period known as <strong>&ldquo;the year without a winter.&rdquo;</strong></li>
</ul>
</div>
<h3>La Nina</h3>
<ul style="list-style-type: square;">
<li>La Nina means The Little Girl in Spanish. It is also sometimes called El Viejo, anti-El Nino, or simply "a cold event."</li>
<li>La Nina events represent periods of <strong>below-average sea surface temperatures</strong> across the <strong>east-central Equatorial Pacific.</strong> <br />
<ul style="list-style-type: circle;">
<li>It is indicated by sea-surface temperature decreased by more than 0.9℉ for at least five successive three-month seasons.</li>
</ul>
</li>
<li>La Nina event is observed when the<strong> water temperature in the Eastern Pacific gets comparatively colder than normal,</strong> as a consequence of which, there is a <strong>strong high pressure over the eastern equatorial Pacific. </strong></li>
</ul>
<p><strong>The Conditions of La Nina.</strong></p>
<ul style="list-style-type: square;">
<li>La Nina is caused by a build-up of<strong> cooler-than-normal waters in the tropical Pacific,</strong> the area of the Pacific Ocean between the Tropic of Cancer and the Tropic of Capricorn.</li>
<li>La Nina is characterized by<strong> lower-than-normal air pressure over the western Pacific.</strong> These low-pressure zones contribute to increased rainfall.</li>
<li>La Nina events are also associated with<strong> rainier-than-normal conditions</strong> over <strong>southeastern Africa and northern Brazil.</strong> <br />
<ul style="list-style-type: circle;">
<li>However, strong La Nina events are associated with catastrophic floods in northern Australia.</li>
</ul>
</li>
<li>La Nina is also characterized by <strong>higher-than-normal pressure</strong> over the <strong>central and eastern Pacific.</strong> <br />
<ul style="list-style-type: circle;">
<li>This results in decreased cloud production and rainfall in that region.</li>
</ul>
</li>
<li><strong>Drier-than-normal conditions</strong> are observed along the <strong>west coast of tropical South America, </strong>the <strong>Gulf Coast of the United States,</strong> and the <strong>pampas region of southern South America.</strong></li>
</ul>
<p><strong>Impact of La Nina</strong></p>
<ul style="list-style-type: square;">
<li><strong>Europe:</strong> In Europe, El Nino reduces the number of autumnal hurricanes. <br />
<ul style="list-style-type: circle;">
<li>La Nina tends to lead to <strong>milder winters in Northern Europe</strong> (especially UK) and colder <strong>winters in southern/western Europe</strong> leading to snow in the Mediterranean region.</li>
</ul>
</li>
<li><strong>North America:</strong> It is continental North America where most of these conditions are felt. The wider effects include:<br />
<ul style="list-style-type: circle;">
<li><strong>Stronger winds along the equatorial region,</strong> especially in the Pacific.</li>
<li><strong>Favourable conditions for hurricanes</strong> in the Caribbean and central Atlantic area.</li>
<li><strong>Greater instances of tornados</strong> in various states of the US.</li>
<li><strong>South America:</strong> La Nina causes<strong> drought in the</strong> South American countries of <strong>Peru and Ecuador.</strong>
<ul style="list-style-type: disc;">
<li>It usually has a <strong>positive impact on the fishing industry</strong> of western South America.</li>
</ul>
</li>
</ul>
</li>
<li><strong>Western Pacific:</strong> In the western Pacific, La Nina increases the<strong> potential for landfall</strong> in those areas most vulnerable to their effects, and especially into <strong>continental Asia and China.</strong>
<ul style="list-style-type: circle;">
<li>It also leads to<strong> heavy floods in Australia.</strong></li>
<li>There are<strong> increased temperatures</strong> in Western Pacific, Indian Ocean and off the Somalian coast.</li>
</ul>
</li>
</ul>
<div class="border-bg">
<p><strong>La Nina in 2010</strong></p>
<ul style="list-style-type: square;">
<li>The 2010 La Nina event correlates with one of the worst floods in the history of Queensland, Australia.</li>
<li>More than 10,000 people were forced to evacuate, and damage from the disaster was estimated at more than $2 billion.</li>
</ul>
</div>
<h3>ENSO and India</h3>
<ul style="list-style-type: square;">
<li><strong>El Nino:</strong> Strong El Nino events contribute to weaker monsoons and even droughts in India Southeast Asia.</li>
<li><strong>La Nina:</strong> The cold air occupies a larger part of India than the El Nino cold air.</li>
<li>In the &lsquo;La Nina year&rsquo;, <strong>rainfall associated with the summer monsoon</strong> in Southeast Asia tends to be <strong>greater than normal,</strong> especially in<strong> northwest India and Bangladesh.</strong> <br />
<ul style="list-style-type: circle;">
<li>This generally <strong>benefits the Indian economy,</strong> which depends on the monsoon for agriculture and industry.</li>
</ul>
</li>
<li>It usually brings in <strong>colder than normal winters</strong> in India.</li>
<li>La Nina influences the Indian subcontinent by piping in<strong> cold air from Siberia and South China,</strong> which interacts with the tropical heating to produce a north-south low-pressure system.</li>
<li>The <strong>cold air of La Nina</strong> associated with this north-south trough <strong>tends to extend much further south into India.</strong> <br />
<ul style="list-style-type: circle;">
<li>This is remarkably different from the more northwest-southeast blast of cold air associated with El Nino.</li>
<li>The pressure pattern going north-south means lesser impact of western disturbances.</li>
<li>The <strong>cold temperature can go down as far as Tamil Nadu, </strong>but <strong>may not affect the North East that much.</strong></li>
</ul>
</li>
</ul>
<p style="text-align: center;"><a href="http://www.drishtiias.com/images/uploads/1610954845_image2.gif" target="_blank" rel="noopener"><strong><img class="content-img" src="http://www.drishtiias.com/images/uploads/1610954845_image2.gif" width="500" caption="false" /></strong></a></p>',
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	(int) 7 => object(Cake\ORM\Entity) {

		'article_id' => (int) 7481,
		'category_id' => (int) 21,
		'title' => 'Semeru Volcano of Indonesia',
		'description' => '<h3>Why in News</h3>
<p>Recently, <strong>Semeru volcano</strong> erupted in<strong> Indonesia&rsquo;s East Java province.</strong> Other volcanoes, such as the <a href="/daily-updates/daily-news-analysis/mt-merapi-of-indonesia" target="_blank" rel="noopener"><strong>Merapi volcano</strong></a> <strong>(Java)</strong> and <a href="/daily-updates/daily-news-analysis/indonesia-s-mt-sinabung-erupted" target="_blank" rel="noopener"><strong>Sinabung volcano</strong></a> <strong>(Sumatra)</strong>, also erupted recently.</p>
<h3>Key Points</h3>
<ul style="list-style-type: square;">
<li><strong>Semeru Volcano:</strong><br />
<ul style="list-style-type: circle;">
<li>Semeru - also known as "The Great Mountain" - is the highest volcano in Java and one of the most active.</li>
<li>It previously erupted in December, 2019.</li>
<li>Indonesia, with the maximum number of active volcanoes in the world, is <strong>prone to seismic upheaval</strong> due to its location on the <strong>Pacific&rsquo;s Ring of Fire.</strong></li>
<li>Semeru volcano is also the part of the <strong>Island arcs</strong> formed by the subduction of the <strong>Indo-Australian plate</strong> below <strong>Sunda Plate</strong> (part of Eurasian Plate). The trench formed here is called Sunda trench whose major section is the Java Trench.</li>
</ul>
</li>
<li><strong>Pacific Ring of Fire:</strong><br />
<ul style="list-style-type: circle;">
<li><strong>The Ring of Fire,</strong> also referred to as the <strong>Circum-Pacific Belt,</strong> is a path along the Pacific Ocean characterized by <strong>active volcanoes and frequent earthquakes.</strong></li>
<li>It traces boundaries between several tectonic plates&mdash;including the Pacific, Cocos, Indian-Australian, Nazca, North American, and Philippine Plates.</li>
</ul>
</li>
</ul>
<p><a href="http://www.drishtiias.com/images/uploads/1610952045_image1.png" target="_blank" rel="noopener"><img class="content-img" src="http://www.drishtiias.com/images/uploads/1610952045_image1.png" style="display: block; margin-left: auto; margin-right: auto;" width="650" caption="false" /></a></p>
<ul style="list-style-type: square;">
<li><strong>Island Arcs:</strong><br />
<ul style="list-style-type: circle;">
<li>They are long, curved chains of <strong>oceanic islands</strong> associated with <strong>intense volcanic and seismic activity and orogenic</strong> (mountain-building) processes. <br />
<ul style="list-style-type: disc;">
<li>An island arc typically has a <strong>land mass or a partially enclosed, unusually shallow sea</strong> on its concave side.</li>
<li>Along the convex side there almost invariably exists a long, <strong>narrow deep-sea trench.</strong></li>
<li>The greatest ocean depths are found in these depressions of the seafloor, as in the case of the <strong>Mariana (deepest trench in the world) and Tonga trenches.</strong></li>
</ul>
</li>
<li>Prime examples of this form of geologic feature include the <strong>Aleutian-Alaska Arc</strong> and the <strong>Kuril-Kamchatka Arc.</strong></li>
</ul>
</li>
</ul>
<p><a href="https://indianexpress.com/article/world/indonesian-semeru-volcano-erupts-spews-ash-5kms-into-sky-7149323/" target="_blank" rel="noopener"><strong>Source: IE</strong></a></p>',
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	(int) 8 => object(Cake\ORM\Entity) {

		'article_id' => (int) 7274,
		'category_id' => (int) 21,
		'title' => 'Winter Solstice',
		'description' => '<h3>Why in News</h3>
<p><strong>21<sup>st</sup> December</strong> or the <strong>Winter Solstice</strong> marks the<strong> shortest day of the year</strong> in the<strong> Northern Hemisphere.</strong> The same day marks the <strong>Summer Solstice,</strong> the year's <strong>longest day,</strong> in the <strong>Southern Hemisphere.</strong></p>
<h3>Key Points</h3>
<ul style="list-style-type: square;">
<li><strong>Solstice:</strong><br />
<ul style="list-style-type: circle;">
<li>It is a <strong>Latin word</strong> that means<strong> &lsquo;stalled sun&rsquo;.</strong> It is a natural phenomenon that occurs<strong> twice every year,</strong> once in the summer and again during winter, in each hemisphere of the earth.</li>
</ul>
</li>
<li><strong>Winter Solstice:<a href="http://www.drishtiias.com/images/uploads/1608637600_image3.png" target="_blank" rel="noopener"><img class="content-img" src="http://www.drishtiias.com/images/uploads/1608637600_image3.png" style="display: block; margin-left: auto; margin-right: auto;" width="650" caption="false" /></a></strong>
<ul style="list-style-type: circle;">
<li>It is the<strong> shortest day and longest night</strong> of the year in the<strong> Northern Hemisphere</strong> and is also known as the <strong>&lsquo;first day of winter&rsquo;</strong> in the Northern Hemisphere as well as <strong>&lsquo;Hiemal solstice or Hibernal solstice&rsquo;.</strong></li>
<li>During this, <strong>countries in the Northern Hemisphere are farthest from the Sun</strong> and the Sun shines overhead on the <strong>Tropic of Capricorn</strong> (23.5&deg; south).<br />
<ul style="list-style-type: disc;">
<li>At latitudes of 23.5&deg; are the Tropics of Cancer and Capricorn, north and south of the Equator.</li>
<li>At 66.5&deg; are the Arctic and Antarctic Circles, to the north and south.</li>
<li>Latitudes are a measure of a location&rsquo;s distance from the Equator.</li>
</ul>
</li>
<li>This situation will be reversed on<strong> 21<sup>st</sup> June,</strong> when the <strong>Northern Hemisphere</strong> will see the <strong>Summer Solstice,</strong> the year&rsquo;s <strong>longest day</strong> and the<strong> Southern Hemisphere</strong> will see the year&rsquo;s <strong>shortest day.</strong></li>
<li>In <strong>Vedic tradition,</strong> the northern movement of the Earth on the celestial sphere is implicitly acknowledged in the<em><strong> Surya Siddhanta</strong></em>, which outlines the <em><strong>Uttarayana</strong></em> (the period between <em>Makar Sankranti</em> and<em> Karka Sankranti</em>). Hence, Winter Solstice is the<strong> first day of<em> Uttarayana.</em></strong></li>
<li><strong>Special Winter Solstice 2020:</strong><br />
<ul style="list-style-type: disc;">
<li>In <strong>2020,</strong> the day is special as it coincides with a<strong> celestial event,</strong> the <a href="/daily-updates/daily-news-analysis/jupiter-saturn-great-conjunction" target="_blank" rel="noopener"><strong>&lsquo;Great Conjunction&rsquo;</strong></a> of <strong>Jupiter and Saturn,</strong> happening after nearly 400 years.</li>
<li>The two planets <strong>come in conjunction when they have the same right ascension or celestial longitude</strong> and that is known as &lsquo;Great Conjunction&rsquo;.</li>
</ul>
</li>
</ul>
</li>
<li><strong>Geography Behind:</strong><br />
<ul style="list-style-type: circle;">
<li>The reason behind the changing lengths of the days is the <strong>Earth&rsquo;s tilt.</strong></li>
<li>The<strong> Earth&rsquo;s axis of rotation is tilted at an angle of 23.5&deg; to its orbital plane.</strong> This tilt, combined with factors such as Earth&rsquo;s spin and orbit, <strong>leads to variations in the duration of sunlight,</strong> due to which any location on the planet receives different lengths of days.<br />
<ul style="list-style-type: disc;">
<li>The Northern Hemisphere spends half the year tilted in the direction of the Sun, getting direct sunlight during long summer days. During the other half of the year, it tilts away from the Sun, and the days are shorter.</li>
</ul>
</li>
<li>The<strong> tilt is also responsible for the different seasons on Earth.</strong> This phenomenon <strong>causes the movement of the Sun from the northern to the southern hemisphere</strong> and vice versa<strong> bringing in seasonal changes</strong> in the year.</li>
</ul>
</li>
</ul>
<p><a href="https://indianexpress.com/article/explained/explained-what-is-the-winter-solstice-which-made-dec-21-the-shortest-day-of-the-year-7113787/" target="_blank" rel="noopener"><strong>Source: IE</strong></a></p>',
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	(int) 9 => object(Cake\ORM\Entity) {

		'article_id' => (int) 7200,
		'category_id' => (int) 21,
		'title' => 'El Niño & Drought',
		'description' => '<h3>Why in News</h3>
<p>In a recent study by<strong> Indian Institute of Science&rsquo;s</strong> (IISc) <strong>Centre for Atmospheric and Oceanic Sciences</strong> (CAOS), it has been found that <a href="/daily-updates/daily-news-analysis/el-nino-forecast-for-2019" target="_blank" rel="noopener"><strong>El Ni&ntilde;o</strong></a> was <strong>not the only cause for droughts</strong> during the Summer <a href="/to-the-points/paper1/monsoon-2" target="_blank" rel="noopener"><strong>Monsoon</strong></a> in the Indian Subcontinent.</p>
<ul style="list-style-type: square;">
<li><strong>El Ni&ntilde;o</strong> is a recurring climate event during which<strong> abnormally warm equatorial Pacific waters pull moisture-laden clouds</strong> away from the <strong>Indian subcontinent.</strong></li>
<li>It is the usual <strong>suspect</strong> for <strong>failing Indian summer monsoons</strong> between <strong>June and September.</strong></li>
</ul>
<h3>Key Points</h3>
<ul style="list-style-type: square;">
<li><strong>Findings of the Study:</strong><br />
<ul style="list-style-type: circle;">
<li>43% of the droughts that occurred during the Indian summer monsoon season in the past century may have been driven by <strong>atmospheric disturbances</strong> from the <strong>North Atlantic region.</strong> <br />
<ul style="list-style-type: disc;">
<li>These<strong> droughts</strong> that India faced occurred during years <strong>when El Ni&ntilde;o was absent.</strong></li>
</ul>
</li>
</ul>
</li>
<li><strong>Cause of these Drought:</strong><br />
<ul style="list-style-type: circle;">
<li>Sudden and steep drop in rainfall in late August that was linked to an <strong>atmospheric disturbance in the mid-latitude region over the North Atlantic Ocean,</strong> creating a <strong>pattern of atmospheric currents</strong> that move over the indian subcontinent and <strong>&ldquo;derail&rdquo; the monsoon.</strong></li>
</ul>
</li>
<li><strong>Change in Drought Pattern:</strong><br />
<ul style="list-style-type: circle;">
<li><strong>El Ni&ntilde;o year drought:</strong><br />
<ul style="list-style-type: disc;">
<li>The<strong> rainfall deficit</strong> begins <strong>mid-June</strong> and spreads throughout the country.</li>
</ul>
</li>
<li><strong>Normal year Drought Condition:</strong><br />
<ul style="list-style-type: disc;">
<li>There is normal rainfall during the monsoon season but a <strong>sudden and steep decline was observed in August.</strong></li>
<li><strong>Causes for this August decline:</strong><br />
<ul style="list-style-type: disc;">
<li>An unusual <strong>atmospheric disturbance</strong> in the<strong> mid-latitudes</strong><br />
<ul style="list-style-type: disc;">
<li>The middle latitudes are spatial regions on Earth <strong>located between the latitudes 23&deg; and 66&deg; north.</strong></li>
</ul>
</li>
<li>The disturbance emerges from<strong> winds in the upper atmosphere</strong> interacting with a <strong>cyclonic circulation</strong> above abnormally<strong> cold North Atlantic waters.</strong><br />
<ul style="list-style-type: disc;">
<li>The resulting wave of air currents, called<strong> a Rossby wave, moves from the North Atlantic</strong> towards the<strong> Tibetan plateau</strong> and <strong>hits the Indian subcontinent </strong>around<strong> mid-August, suppressing rainfall and causing drought-like conditions.</strong></li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
</ul>
</li>
</ul>
<div class="border-bg">
<p><strong>Other Atmospheric Circulations that Impact Monsoon</strong></p>
<ul style="list-style-type: square;">
<li><strong>Indian Ocean Dipole:</strong><br />
<ul style="list-style-type: circle;">
<li>The Indian Ocean Dipole (IOD) is defined by the<strong> difference in sea surface temperature between two areas</strong> (or poles, hence a dipole) &ndash; a western pole in the <strong>Arabian Sea</strong> (western Indian Ocean) and an <strong>eastern pole</strong> in the eastern Indian Ocean <strong>south of Indonesia.</strong></li>
<li>IOD develops in the equatorial region of Indian Ocean<strong> from April to May</strong> peaking in October.</li>
<li>With a <strong>positive IOD</strong> winds over the Indian Ocean blow from east to west (from Bay of Bengal towards Arabian Sea). This results in the <strong>Arabian Sea</strong> (western Indian Ocean near African Coast) being much <strong>warmer and eastern Indian Ocean around Indonesia becoming colder and dry.</strong></li>
<li>In the <strong>negative dipole</strong> year (negative IOD), <strong>reverse happens</strong> making Indonesia much warmer and rainier.<a href="http://www.drishtiias.com/images/uploads/1607930138_image2.png" target="_blank" rel="noopener"><img class="content-img" src="http://www.drishtiias.com/images/uploads/1607930138_image2.png" style="display: block; margin-left: auto; margin-right: auto;" width="350" caption="false" /></a></li>
<li><strong>Indian Ocean Dipole effect:</strong><br />
<ul style="list-style-type: disc;">
<li>It was demonstrated that a <strong>positive IOD index</strong> often negated the effect of El Nino, resulting in increased Monsoon rains in several El Nino years like the 1983, 1994 and 1997.</li>
<li>Two poles of the IOD &ndash; the<strong> eastern pole</strong> (around Indonesia) and the <strong>western pole</strong> (off the African coast) were independently and cumulatively affecting the quantity of rains for the Monsoon in the Indian subcontinent.</li>
</ul>
</li>
<li>Impact of IOD on<strong> Cyclogenesis</strong> in Northern Indian Ocean:<br />
<ul style="list-style-type: disc;">
<li>Positive IOD (Arabian Sea warmer than Bay of Bengal) results in <strong>more cyclones than usual in Arabian Sea.</strong></li>
<li>Negative IOD results in<strong> stronger than usual <a href="/to-the-points/paper1/cyclone-19" target="_blank" rel="noopener">Tropical Cyclones</a></strong> in the Bay of Bengal. Cyclonic activity in Arabian Sea is <strong>suppressed.</strong></li>
</ul>
</li>
</ul>
</li>
<li><strong>Madden-Julian Oscillation, or MJO</strong> <br />
<ul style="list-style-type: circle;">
<li>The Madden&ndash;Julian Oscillation (MJO), is an eastward <strong>moving band of rain clouds</strong> that travels around the globe spanning 12,000&ndash;20,000 km across the tropical oceans returning to its initial starting point in 30 to 60 days.</li>
<li>In its journey, it interacts with<strong> surface waters</strong> of the Indo-Pacific ocean, the <strong>largest pool of warm water in the globe.<a href="http://www.drishtiias.com/images/uploads/1607930099_image1.png" target="_blank" rel="noopener"><img class="content-img" src="http://www.drishtiias.com/images/uploads/1607930099_image1.png" style="display: block; margin-left: auto; margin-right: auto;" width="500" caption="false" /></a></strong></li>
<li>The MJO consists of two parts, or phases: one is the <strong>enhanced rainfall</strong> (or convective) phase and the other is the <strong>suppressed rainfall phase.</strong></li>
<li>Strong MJO activity often<strong> dissects the planet into halves:</strong><br />
<ul style="list-style-type: disc;">
<li>One half within the<strong> enhanced convective phase</strong> and the other half in <strong>the suppressed convective phase.</strong> These two phases produce opposite changes in clouds and rainfall and this entire dipole propagates eastward.</li>
</ul>
</li>
</ul>
</li>
<li><strong>Effects of MJO on global weather phenomenon:</strong><br />
<ul style="list-style-type: circle;">
<li>It can modulate the<strong> timing and strength of monsoons.</strong></li>
<li>It<strong> Influences tropical cyclone</strong> numbers and strength in nearly all ocean basins.</li>
<li>It can result in <strong>jet stream changes</strong> that can lead to cold air outbreaks, extreme heat events, and flooding rains over the United States and North America.</li>
</ul>
</li>
</ul>
</div>
<p><a href="https://timesofindia.indiatimes.com/home/science/43-indian-droughts-influenced-by-north-atlantic-air-currents/articleshow/79673081.cms" target="_blank" rel="noopener"><strong>Source:TOI</strong></a></p>',
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	(int) 10 => object(Cake\ORM\Entity) {

		'article_id' => (int) 7131,
		'category_id' => (int) 21,
		'title' => 'Cyclone Burevi',
		'description' => '<h3>Why in News</h3>
<p>Recently <strong>cyclone Burevi</strong> has made a landfall on Sri Lanka&rsquo;s Northern and Eastern provinces, before heading towards south India.</p>
<ul style="list-style-type: square;">
<li>This comes days after <a href="/daily-updates/daily-news-analysis/cyclone-nivar" target="_blank" rel="noopener"><strong>Cyclone Nivar</strong></a> hit the Puducherry coast.</li>
</ul>
<h3>Key Points</h3>
<ul style="list-style-type: square;">
<li><strong>Named by:</strong> <br />
<ul style="list-style-type: circle;">
<li>Maldives</li>
</ul>
</li>
<li><strong>Burevi vs Nivar:</strong><br />
<ul style="list-style-type: circle;">
<li>Cyclone Burevi would <strong>not strengthen beyond the intensity of a cyclonic storm</strong> because of <strong>upwelling</strong> caused by Nivar.</li>
<li>Upwelling is the process in which <strong>cooler waters from lower ocean surfaces are pushed towards upper ocean surfaces.</strong></li>
<li>In the absence of warm sea surface conditions, any cyclone, in this case Burevi, will <strong>not get enough fuel to intensify</strong> further while at sea.</li>
<li>Further, interaction with land mass has slowed its movement and intensity.</li>
</ul>
</li>
</ul>
<h3>Tropical Cyclone</h3>
<ul style="list-style-type: square;">
<li>A tropical cyclone is an intense circular storm that originates <strong>over warm tropical oceans</strong> and is characterized by low atmospheric pressure, high winds, and heavy rain.</li>
<li>A characteristic feature of tropical cyclones is the<strong> eye,</strong> a central region of clear skies, warm temperatures, and low atmospheric pressure.</li>
<li>Storms of this type<strong> are called</strong> hurricanes in the North Atlantic and eastern Pacific and typhoons in SouthEast Asia and China. They are called tropical cyclones in the southwest Pacific and Indian Ocean region and Willy-willies in north-western Australia.</li>
<li>Storms rotate <strong>counterclockwise in the northern hemisphere </strong>and<strong> clockwise in the southern hemisphere.</strong></li>
<li>The conditions favourable for the formation and intensification of tropical storms are:<br />
<ul style="list-style-type: circle;">
<li>Large sea surface with<strong> temperature higher than 27&deg;C.</strong></li>
<li>Presence of the Coriolis force.</li>
<li>Small variations in the vertical wind speed.</li>
<li>A pre-existing weak low- pressure area or low-level-cyclonic circulation.</li>
<li>Upper divergence above the sea level system.</li>
</ul>
</li>
</ul>
<p><a href="https://www.thehindu.com/news/national/tamil-nadu/burevi-weakens-into-a-deep-depression/article33244118.ece" target="_blank" rel="noopener"><strong>Source: TH</strong></a></p>',
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	(int) 11 => object(Cake\ORM\Entity) {

		'article_id' => (int) 7129,
		'category_id' => (int) 21,
		'title' => 'Provisional Report on the State of the Global Climate 2020: WMO',
		'description' => '<h3>Why in News</h3>
<p>According to the latest <strong>State of the Global Climate provisional report by the <a href="/daily-updates/daily-news-analysis/state-of-the-global-climate-wmo" target="_blank" rel="noopener">World Meteorological Organization</a> (WMO),</strong> the year<strong> 2020 is set to be among the three warmest</strong> on record. Also, the <strong>decade 2011-2020 would be the warmest</strong> ever.</p>
<ul style="list-style-type: square;">
<li>The<strong> final report</strong> will be published in <strong>March 2021.</strong> The <strong>State of the Global Climate report</strong> is published <strong>annually</strong> to keep a track of global warming.</li>
<li><strong>WMO</strong> is one of the specialized agencies of the<a href="/important-institutions/drishti-specials-important-institutions-international-institution/united-nations-1" target="_blank" rel="noopener"><strong> United Nations (UN).</strong></a></li>
</ul>
<h3>Key Points</h3>
<ul style="list-style-type: square;">
<li><strong>Rise in Global Temperature:</strong><br />
<ul style="list-style-type: circle;">
<li>The global mean surface temperature for January-October 2020 was<strong> 1.2 degree Celsius higher</strong> than the pre-industrial baseline (1850-1900).<br />
<ul style="list-style-type: disc;">
<li>There is at least a one in five chance of it <strong>temporarily exceeding 1.5 &deg;C</strong> by 2024.</li>
<li>The <a href="/loksabha-rajyasabha-discussions/the-big-picture-climate-change-act-now" target="_blank" rel="noopener"><strong>Paris Agreement</strong></a> central aim is to strengthen the global response to the threat of climate change by keeping a global temperature rise this century well below 2 degrees Celsius above pre-industrial levels and to pursue efforts to limit the temperature increase even further to 1.5 degrees Celsius.</li>
</ul>
</li>
<li><strong>2020 will be one of the three hottest,</strong> just behind<strong> 2016 and 2019.</strong><br />
<ul style="list-style-type: disc;">
<li>The record heat in 2020 has been <strong>despite near-<a href="/daily-updates/daily-news-analysis/el-nino-forecast-for-2019" target="_blank" rel="noopener">La Ni&ntilde;a</a></strong> conditions prevailing in the equatorial Pacific Ocean since August and <strong>moderate La Ni&ntilde;a</strong> conditions prevailing since October.</li>
<li>The<strong> La Ni&ntilde;a phase of the <a href="/printpdf/el-nino-forecast-for-2019" target="_blank" rel="noopener">El Ni&ntilde;o Southern Oscillation (ENSO)</a></strong> phenomenon generally has a cooling effect on many parts of the world.</li>
</ul>
</li>
</ul>
</li>
<li><strong>High Temperature over Ocean Surfaces:</strong><br />
<ul style="list-style-type: circle;">
<li><strong>80%</strong> of ocean areas have experienced at least one <strong>marine heat wave (MHW)</strong> so far in 2020.<br />
<ul style="list-style-type: disc;">
<li><a href="/daily-updates/daily-news-analysis/heat-waves" target="_blank" rel="noopener"><strong>Heat wave</strong></a> is a period of prolonged abnormally high surface temperatures relative to those normally expected.</li>
<li>At the time of<strong> MHW,</strong> the average temperature of the ocean surface (up to a depth of 300 feet or more) rises by <strong>5-7&deg;C</strong> above normal.</li>
<li>MHWs can be<strong> caused by</strong> locally formed heat fluxes between the atmosphere and the ocean or due to large-scale drivers of the Earth&rsquo;s climate like the <strong>ENSO.</strong></li>
<li>There were also much more strong MHWs<strong> (43%)</strong> over the oceans in 2020 than moderate ones <strong>(28%).</strong></li>
</ul>
</li>
<li><strong>Global sea-level rise</strong> was also similar to 2019 value.This was mainly <strong>due to the increased melting of the ice sheets in Greenland and Antarctica.</strong></li>
</ul>
</li>
<li><strong>Reasons:</strong> Scientific evidence indicates<strong> increasing temperatures</strong> are a direct result of <strong>human-led <a href="/printpdf/global-warming-of-1-5-c-ipcc-report" target="_blank" rel="noopener">global warming</a></strong> which is an impact of the <strong>emission of <a href="/daily-updates/daily-news-analysis/greenhouse-gas-levels-reach-record-highs-un-report" target="_blank" rel="noopener">greenhouse gases (GHG).</a></strong><br />
<ul style="list-style-type: circle;">
<li>After <strong>record GHG levels of 2019,</strong> there has been a slight<strong> dip this year</strong> due to measures taken by many countries to fight the ongoing <strong><a href="/daily-updates/daily-news-analysis/coronaviruses" target="_blank" rel="noopener">novel coronavirus</a> disease <a href="/daily-updates/daily-news-editorials/covid-19-and-indian-federalism" target="_blank" rel="noopener">(Covid-19 pandemic).</a></strong></li>
<li>However, data from specific locations, including Mauna Loa (Hawaii) and Cape Grim (Tasmania) indicate that levels of <strong>Carbon dioxide (CO<sub>2</sub>), Methane (CH<sub>4</sub>) and Nitrogen dioxide (N<sub>2</sub>O) continued to increase</strong> in 2020.</li>
</ul>
</li>
<li><strong>Consequences of Global Warming in 2020:</strong><br />
<ul style="list-style-type: circle;">
<li><strong>Extreme weather events</strong> such as <strong>tropical cyclones, floods, heavy rainfall and droughts</strong> impacted many parts of the world and <a href="/daily-updates/daily-news-analysis/climate-change-and-forest-fire-link" target="_blank" rel="noopener"><strong>cases of wildfire</strong></a> have also increased this year.<br />
<ul style="list-style-type: disc;">
<li><strong>Atlantic Hurricane Season:</strong> The<strong><a href="/daily-updates/daily-news-analysis/hurricane-laura#:~:text=The%20Atlantic%20hurricane%20season%20runs,as%20a%20Category%201%20storm." target="_blank" rel="noopener"> season</a></strong> witnessed <strong>30 named storms</strong> from June to November which is the <strong>highest number ever</strong> recorded.</li>
<li><strong>Heavy Rains:</strong> There was heavy rainfall and flooding in many parts of <strong>Asia and Africa.</strong></li>
<li><strong>Droughts:</strong> South America experienced<strong> severe droughts</strong> with northern Argentina, Paraguay and western areas of Brazil being some of the worst affected.</li>
</ul>
</li>
<li><strong>Sea-level rise:</strong> Melting of ice resulted in sea level rise which is an existential concern for the small island nations.<br />
<ul style="list-style-type: disc;">
<li>A significant sea-level rise by the end of the century will mean that these countries will drown in the oceans and their respective populations will be homeless.</li>
</ul>
</li>
<li><strong>Loss to Humanity:</strong><br />
<ul style="list-style-type: disc;">
<li><strong>Population Movements:&nbsp;</strong>The climate and weather events have triggered significant population movements and have severely affected vulnerable people on the move, including in the Pacific region and Central America.</li>
<li><strong>Agricultural Losses:</strong> Brazil alone recorded agricultural losses of 3 billion American dollars.</li>
<li><strong>Loss of Human lives, Property and Livelihoods:</strong> The most affected were the Sahel and Greater Horn regions of Africa and China, India, Korea and Japan regions of Asia.</li>
</ul>
</li>
</ul>
</li>
</ul>
<h3>Way Forward</h3>
<ul style="list-style-type: square;">
<li>Environmental ethics should take precedence over other issues like national and strategic interest or economic interest.</li>
<li><strong>Oil, gas and coal production must fall six percent a year</strong> in order to limit catastrophic global warming, as per the <strong>UN's annual Production Gap assessment,</strong> which measures the difference between the Paris goals and countries' fossil fuel production plans.</li>
<li>There needs an enhanced commitment from nations more than their pledged INDCs (Intended Nationally Determined Contributions) under the <strong>Paris Agreement.</strong> However, it must not be used to pressurize developing countries to ramp up their global warming mitigation targets.</li>
</ul>
<p><a href="https://indianexpress.com/article/weather/2020-set-to-be-one-of-warmest-years-on-record-7076661/" target="_blank" rel="noopener"><strong>Source:IE</strong></a></p>',
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	(int) 12 => object(Cake\ORM\Entity) {

		'article_id' => (int) 7075,
		'category_id' => (int) 21,
		'title' => 'Subdued Northeast Monsoon',
		'description' => '<h3>Why in News</h3>
<p><strong>Rainfall over the southern peninsular region has been deficient so far,</strong> indicating that the northeast monsoon has remained subdued this year.</p>
<h3>Key Points</h3>
<ul style="list-style-type: square;">
<li><strong>Pattern of Rainfall in India:</strong> India receives rainfall during<strong> two seasons:</strong><br />
<ul style="list-style-type: circle;">
<li>About <strong>75% of the country&rsquo;s annual rainfall</strong> is received from the<a href="/to-the-points/paper1/monsoon-2" target="_blank" rel="noopener"><strong> Southwest monsoon</strong></a> between<strong> June and September.</strong></li>
<li>The <strong>Northeast monsoon</strong> occurs during <strong>October to December,</strong> and is a <strong>comparatively small-scale monsoon,</strong> which is confined to the <strong>Southern peninsula.</strong> It is called the<strong> winter monsoon.</strong></li>
</ul>
</li>
<li><strong>Northeast Monsoon and Rainfall:</strong><br />
<ul style="list-style-type: circle;">
<li>After the<strong> complete withdrawal of the Southwest monsoon</strong> from the country takes place by<strong> mid-October,</strong> the <strong>wind pattern rapidly changes</strong> from the<strong> south-westerly to the north-easterly direction.</strong></li>
<li>The period after the Southwest monsoon season, from October to December, is the <strong>peak time for cyclonic activity in the North Indian Ocean region</strong> covering the Arabian Sea and the Bay of Bengal.<br />
<ul style="list-style-type: disc;">
<li>The winds associated with the formation of low pressure systems, depressions, or cyclones <strong>influence this monsoon,</strong> and therefore, the rainfall.</li>
</ul>
</li>
</ul>
</li>
<li><strong>Regions associated with Northeast Monsoon:</strong><br />
<ul style="list-style-type: circle;">
<li>The rainfall associated with the Northeast monsoon is important for <strong>Tamil Nadu, Puducherry, Karaikal, Yanam, coastal Andhra Pradesh, Kerala, north interior Karnataka, Mahe and Lakshadweep.</strong></li>
<li>Tamil Nadu records about<strong> 48% of its annual rainfall</strong> during these months, making it the key factor for<strong> undertaking agricultural activities and reservoir management</strong> in the state.</li>
<li>Some South Asian countries such as <strong>Maldives, Sri Lanka and Myanmar,</strong> too, record rainfall during October to December.</li>
</ul>
</li>
<li><strong>Reasons for deficient rainfall this Northeast monsoon:</strong><br />
<ul style="list-style-type: circle;">
<li><strong>Prevailing La Ni&ntilde;a conditions in the Pacific Ocean:</strong>
<ul style="list-style-type: disc;">
<li>La Ni&ntilde;a conditions <strong>enhance the rainfall associated with the Southwest monsoon,</strong> but has a<strong> negative impact</strong> on rainfall associated with the<strong> Northeast monsoon.</strong></li>
<li>La Ni&ntilde;a (Spanish for &lsquo;little girl&rsquo;) refers to the <strong>large-scale cooling of the ocean surface temperatures in the central and eastern equatorial Pacific Ocean,</strong> coupled with changes in the tropical atmospheric circulation, namely winds, pressure and rainfall.</li>
<li>It usually<strong> has the opposite impacts on weather and climate as <a href="/daily-updates/daily-news-analysis/el-nino-threatens-monsoon" target="_blank" rel="noopener">El Ni&ntilde;o</a></strong>, which is the warm phase of the so-called <strong>El Ni&ntilde;o Southern Oscillation (ENSO).</strong>
<ul style="list-style-type: disc;">
<li><strong>El Ni&ntilde;o</strong> (Spanish for &lsquo;little boy&rsquo;) is the<strong> abnormal surface warming observed along the eastern and central regions of the Pacific Ocean</strong> (region between Peru and Papua New Guinea).</li>
<li>La Nina and El Nino are <strong>large-scale ocean phenomena</strong> which influence the global weather winds, temperature and rainfall.</li>
<li>They have the <strong>ability to trigger extreme weather events</strong> like droughts, floods, hot and cold conditions, globally.</li>
<li>Each cycle can last anywhere <strong>between 9 to 12 months, at times extendable to 18 months</strong> and re-occur after<strong> every three to five years.</strong></li>
</ul>
</li>
</ul>
</li>
<li><strong>Inter Tropical Convective Zone (ITCZ):</strong>
<ul style="list-style-type: disc;">
<li>The current position of the ITCZ has also contributed to the poor rainfall during the ongoing monsoon season.</li>
<li>The ITCZ is <strong>a low-pressure belt,</strong> whose northward and southward movements along the equator determine the precipitation in the tropics.</li>
<li>Currently, the <strong>ITCZ is located to the north of its normal position.</strong></li>
</ul>
</li>
</ul>
</li>
</ul>
<div class="border-bg">
<p><strong>Other Important Atmospheric Circulation</strong></p>
<ul style="list-style-type: square;">
<li><a href="/daily-updates/daily-news-analysis/madden-julian-oscillation-mjo" target="_blank" rel="noopener"><strong>Madden-Julian Oscillation (MJO)</strong></a>: The MJO can be defined as an eastward moving 'pulse' of clouds, rainfall, winds and pressure near the equator that typically recurs every 30 to 60 days.</li>
</ul>
</div>
<p><a href="https://indianexpress.com/article/explained/india-northeast-monsoon-rainfall-deficiency-explained-7063467/" target="_blank" rel="noopener"><strong>Source: IE</strong></a></p>',
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	(int) 13 => object(Cake\ORM\Entity) {

		'article_id' => (int) 7074,
		'category_id' => (int) 21,
		'title' => 'Cyclone Nivar',
		'description' => '<h3>Why in News</h3>
<p>Recently, the<a href="/to-the-points/paper1/cyclone-19" target="_blank" rel="noopener"><strong> tropical cyclone</strong> </a><strong>Nivar</strong> has made landfall along the <strong>Tamil Nadu-Puducherry</strong> coast.</p>
<ul style="list-style-type: square;">
<li>Landfall refers to the phenomenon of a cyclone&rsquo;s outer wall moving over the coastline and beyond.</li>
</ul>
<h3>Key Points</h3>
<ul style="list-style-type: square;">
<li><strong>Tropical Cyclone:</strong><br />
<ul style="list-style-type: circle;">
<li>A tropical cyclone is an intense circular storm that <strong>originates over warm tropical oceans</strong> and is<strong> characterized by</strong> low atmospheric pressure, high winds, and heavy rain.</li>
<li>A characteristic feature of tropical cyclones is the <strong>eye,</strong> a central region of clear skies, warm temperatures, and low atmospheric pressure.</li>
<li>Storms of this type are called<strong> hurricanes in the North Atlantic</strong> and eastern Pacific and <strong>typhoons in SouthEast Asia</strong> and China. They are called <strong>tropical cyclones</strong> in the <strong>southwest Pacific and Indian Ocean region</strong> and <strong>Willy-willies in north-western Australia.</strong></li>
<li>Storms<strong> rotate anticlockwise</strong> in the<strong> northern hemisphere</strong> and clockwise in the southern hemisphere.</li>
</ul>
</li>
<li><strong>Cyclone Nivar:</strong><br />
<ul style="list-style-type: circle;">
<li>It is the <strong>fourth cyclone</strong> that has taken shape in the North Indian Ocean region this year. The first three cyclones were <strong>Cyclone Gati</strong> (made landfall in Somalia in November), <a href="/daily-updates/daily-news-analysis/cyclone-amphan" target="_blank" rel="noopener"><strong>Cyclone Amphan</strong></a> (eastern India witnessed it in May), and <a href="/daily-updates/daily-news-analysis/cyclone-nisarga" target="_blank" rel="noopener"><strong>Cyclone Nisarga</strong></a> (in Maharashtra).</li>
<li>Nivar will be the <strong>second cyclone to hit Tamil Nadu in two years</strong> after <a href="/daily-updates/daily-news-analysis/cyclone-gaja" target="_blank" rel="noopener"><strong>Cyclone Gaja</strong></a> in 2018.</li>
<li>The storm has been <strong>named Cyclone Nivar,</strong> based on the <strong>guidelines of the World Meteorological Organisation (WMO).</strong> Nivara has been <strong>selected from the list of names given by Iran.</strong><br />
<ul style="list-style-type: disc;">
<li>According to WMO guidelines, countries in every region are supposed to give names for cyclones.</li>
<li>The North Indian Ocean Region covers tropical cyclones formed over Bay of Bengal and Arabian Sea.</li>
<li>The <strong>13 members,</strong> which come under the region, are Bangladesh, India, Maldives, Myanmar, Oman, Pakistan, Sri Lanka, Thailand, Iran, Qatar, Saudi Arabia, the UAE and Yemen.</li>
<li>A <strong>total of 169 cyclones were named</strong> by these countries for this year, with <strong>13 names from each country.</strong></li>
</ul>
</li>
<li>It has weakened from a very severe cyclonic storm to a severe cyclonic storm with a wind speed of 100-110 km per hour.</li>
</ul>
</li>
</ul>
<p><a href="http://www.drishtiias.com/images/uploads/1606382334_image3.png" target="_blank" rel="noopener"><img class="content-img" src="http://www.drishtiias.com/images/uploads/1606382334_image3.png" style="display: block; margin-left: auto; margin-right: auto;" caption="false" width="700" height="407" /></a></p>
<ul style="list-style-type: square;">
<li><strong>Government Steps:</strong><br />
<ul style="list-style-type: circle;">
<li>The <strong>Tamil Nadu government</strong> has announced a <strong>public holiday</strong> under the <strong>Negotiable Instruments Act, 1881,</strong> in 16 districts, including Chennai, considering the impact of Cyclone Nivar.</li>
<li><strong>Fishing activities</strong> have been <strong>restricted and residents evacuated</strong> in coastal areas hit by the cyclone. The <a href="/important-institutions/drishti-specials-important-institutions-national-institutions/national-disaster-management-authority-ndma-" target="_blank" rel="noopener"><strong>National Disaster Response Force (NDRF)</strong></a> has deployed its teams in the affected regions.</li>
</ul>
</li>
</ul>
<p><a href="https://indianexpress.com/article/india/tamil-nadu-puducherry-brace-for-cyclone-nivar-7064447/" target="_blank" rel="noopener"><strong>Source:IE</strong></a></p>',
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		'category_id' => (int) 21,
		'title' => 'Earthquake Concentrations in Dharchula Region',
		'description' => '<h3>Why in News</h3>
<p>Recently, scientists at <a href="/daily-updates/daily-news-analysis/tectonically-active-zone-of-himalayas" target="_blank" rel="noopener"><strong>Wadia Institute of Himalayan Geology</strong></a> (WIHG) have unearthed large concentrations of micro and moderate magnitude <a href="/to-the-points/paper1/earthquake-4" target="_blank" rel="noopener"><strong>earthquakes</strong> </a>in the Dharchula region and adjoining areas of Kumaon Himalaya.</p>
<ul style="list-style-type: square;">
<li>WIHG is an autonomous institute under the <a href="/daily-updates/daily-news-analysis/50th-foundation-day-of-dst" target="_blank" rel="noopener"><strong>Department of Science and Technology</strong> </a>(DST), Government of India.</li>
</ul>
<h3>Key Points</h3>
<ul style="list-style-type: square;">
<li><strong>Location:</strong><br />
<ul style="list-style-type: circle;">
<li>The major concentration is in an area <strong>around 45 km from the <a href="/daily-updates/daily-news-analysis/new-road-to-kailash-mansarovar" target="_blank" rel="noopener">new Kailash Mansarovar road</a></strong>, connecting <strong>Dharchula in Uttarakhand to Lipu Lekh on the China border.</strong></li>
<li>The region is known as the<strong> Central Seismic Gap</strong> (CSG)<strong> region,</strong> despite the <a href="/daily-updates/daily-news-analysis/re-measuring-mount-everest#:~:text=China%20and%20Nepal%20are%20soon,and%20announce%20the%20findings%20together." target="_blank" rel="noopener"><strong>Himalayas</strong> </a>being one of the most tectonically and seismically active regions in the country.<br />
<ul style="list-style-type: disc;">
<li>A gap is a term used to<strong> denote an area with little tectonic activity.</strong></li>
</ul>
</li>
</ul>
</li>
<li><strong>Methodology:</strong><br />
<ul style="list-style-type: circle;">
<li>Scientists started investigating and mapping the region precisely to find out the <strong>reason behind the occurrence of crowded</strong> (closely located and frequently felt) <strong>earthquakes.</strong></li>
<li>They <strong>established a seismological network of 15 broadband seismological stations</strong> along the <a href="/daily-updates/daily-news-analysis/kalapani-territory" target="_blank" rel="noopener"><strong>Kali River</strong></a> valley to investigate the subsurface configuration in the Kumaon Himalaya region with support from the Ministry of Earth Sciences.</li>
</ul>
</li>
<li><strong>Findings:</strong><br />
<ul style="list-style-type: circle;">
<li>These large concentrations of earthquakes are <strong>&ldquo;release of stress&rsquo;&rsquo;</strong> building up in the region and the geological structure behind it.</li>
<li>The Dharchula region <strong>falls between two knee-like structures, </strong>which<strong> traps the stress in this region.</strong></li>
<li>This is the reason why there have been crowded earthquakes here within a span of years and numerous smaller earthquakes have occurred here and the stress keeps building up.</li>
<li>For the stress to be finally released, there is a<strong> likelihood of a high magnitude earthquake in the region.</strong> However it is not possible to predict the scale or the exact time that an earthquake will occur.</li>
</ul>
</li>
</ul>
<div class="border-bg">
<p><strong>Earthquake</strong></p>
<ul style="list-style-type: square;">
<li>An earthquake in simple words is the<strong> shaking of the earth.</strong> It is a <strong>natural event which is caused due to release of energy,</strong> which generates <strong>seismic waves</strong> that travel in all directions.</li>
<li>The location below the earth&rsquo;s surface where the earthquake starts is called the <strong>hypocenter,</strong> and the location directly above it on the surface of the earth is called the <strong>epicenter.</strong></li>
<li><strong>Types of Earthquakes:</strong><br />
<ul style="list-style-type: circle;">
<li>Based on <strong>reasons behind their origins:</strong><br />
<ul style="list-style-type: disc;">
<li>Fault Zones Earthquake.</li>
<li>Tectonic Earthquake.</li>
<li>Volcanic Earthquake.</li>
<li>Human Induced Earthquakes.</li>
</ul>
</li>
<li>Based on the <strong>depth of focus:</strong><br />
<ul style="list-style-type: disc;">
<li>Shallow Earthquakes (0-70 km deep)</li>
<li>Intermediate Earthquakes (70-300 deep)</li>
<li>Deep Earthquakes (300-700 km deep).</li>
</ul>
</li>
</ul>
</li>
<li><strong>Measurement of Earthquakes:</strong><br />
<ul style="list-style-type: circle;">
<li><strong>Seismometers</strong> detects seismic waves below the instrument and records them as a series of zig-zags.<br />
<ul style="list-style-type: disc;">
<li>Scientists can determine the time, location and intensity of an earthquake from the information recorded by a seismometer. This record also provides information about the rocks the seismic waves traveled through.</li>
</ul>
</li>
<li>The earthquake events are<strong> scaled either according to the magnitude or intensity of the shock.</strong><br />
<ul style="list-style-type: disc;">
<li>The <strong>magnitude scale is known as the Richter scale.</strong> The magnitude relates to the energy released during the quake. The magnitude is <strong>expressed in absolute numbers, 0-10.</strong></li>
<li>The <strong>intensity scale is named after Mercalli,</strong> an Italian seismologist. The intensity scale takes into account the visible damage caused by the event. The <strong>range of intensity scale is from 1-12.</strong></li>
</ul>
</li>
</ul>
</li>
</ul>
<p><strong>Earthquakes in India</strong></p>
<ul style="list-style-type: square;">
<li>India is<strong> one of the highly earthquake affected countries</strong> because of the presence of <strong>tectonically active young fold mountains, Himalayas.</strong></li>
<li>India has been divided into<strong> four seismic zones (II, III, IV, and V)</strong> based on scientific inputs relating to seismicity, earthquakes occurred in the past and tectonic setup of the region.</li>
</ul>
<p><a href="http://www.drishtiias.com/images/uploads/1604996922_image2.jpg" target="_blank" rel="noopener"><img class="content-img" src="http://www.drishtiias.com/images/uploads/1604996922_image2.jpg" style="display: block; margin-left: auto; margin-right: auto;" width="650" caption="false" /></a></p>
</div>
<p><a href="https://indianexpress.com/article/india/stress-build-up-in-dharchula-region-scientists-warn-of-major-earthquake-7036837/" target="_blank" rel="noopener"><strong>Source: IE</strong></a></p>',
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	(int) 15 => object(Cake\ORM\Entity) {

		'article_id' => (int) 6927,
		'category_id' => (int) 21,
		'title' => 'Hurricane Eta',
		'description' => '<h3>Why in News</h3>
<p><strong>Recently, Hurricane Eta</strong> has hit northeastern <strong>Nicaragua</strong> with life-threatening storm surge, catastrophic winds and flash flooding occurring over <strong>portions of Central America.</strong></p>
<p><a href="http://www.drishtiias.com/images/uploads/1604567853_image7.png" target="_blank" rel="noopener"><strong><img class="content-img" src="http://www.drishtiias.com/images/uploads/1604567853_image7.png" style="display: block; margin-left: auto; margin-right: auto;" width="550" caption="false" /></strong></a></p>
<h3>Key Points</h3>
<ul style="list-style-type: square;">
<li><strong>Description:</strong> It is categorised as a <strong>Category 4 hurricane.</strong> A Category 4 storm has wind speeds between <strong>130-156 mph</strong> and can uproot trees and bring down power lines.</li>
</ul>
<div class="border-bg">
<p><strong>Saffir-Simpson Hurricane Wind Scale</strong></p>
<ul style="list-style-type: square;">
<li>Hurricanes are categorized on the Saffir-Simpson Hurricane Wind Scale, which rates them on a scale of 1 to 5 based on wind speed.<br />
<ul style="list-style-type: circle;">
<li>Hurricanes that reach category three or higher are classified as major hurricanes.</li>
</ul>
</li>
</ul>
</div>
<p><a href="http://www.drishtiias.com/images/uploads/1604567793_image4.jpg" target="_blank" rel="noopener"><img class="content-img" src="http://www.drishtiias.com/images/uploads/1604567793_image4.jpg" style="display: block; margin-left: auto; margin-right: auto;" width="550" caption="false" /></a></p>
<ul style="list-style-type: square;">
<li><strong>Origin:</strong> Tropical cyclones or hurricanes use warm, moist air as fuel, and therefore form over warm Equatorial water.</li>
<li><strong>Mechanism:</strong><br />
<ul style="list-style-type: circle;">
<li><strong>Low-Pressure Creation:</strong> When the warm, moist air rises upward from the surface of the ocean, it creates an area of low air pressure below.<br />
<ul style="list-style-type: disc;">
<li>When this happens, the air from the surrounding areas rushes to fill this place, eventually rising when it becomes warm and moist too.</li>
<li>An <strong>eye forms</strong> in the centre. It is the calmest part of the cyclone. Before the wind reaches the centre it gets warmed up and rises upwards.</li>
</ul>
</li>
<li>When the warm air rises and cools off, the moisture forms clouds. This system of clouds and winds continues to grow and spin.</li>
<li>This disturbance is fuelled by the ocean&rsquo;s heat and the water that evaporates from its surface.</li>
<li>Such storm systems rotate faster and faster. Storms that form towards the north of the equator <strong>rotate counterclockwise, w</strong>hile those that form to the<strong> south spin clockwise</strong> because of the rotation of the Earth.</li>
</ul>
</li>
</ul>
<p><a href="http://www.drishtiias.com/images/uploads/1604567892_image3.jpg" target="_blank" rel="noopener"><img class="content-img" src="http://www.drishtiias.com/images/uploads/1604567892_image3.jpg" width="550" caption="false" style="display: block; margin-left: auto; margin-right: auto;" /></a></p>
<p><a href="https://indianexpress.com/article/world/hurricane-eta-slams-into-nicaragua-grinds-inland-6936772/" target="_blank" rel="noopener"><strong>Source:IE</strong></a></p>',
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	(int) 16 => object(Cake\ORM\Entity) {

		'article_id' => (int) 6866,
		'category_id' => (int) 21,
		'title' => 'Tectonically Active Zone of Himalayas',
		'description' => '<h3>Why in News</h3>
<p>Recently, a group of scientists from the <strong>Wadia Institute of Himalayan Geology</strong> (WIHG), Dehradun have found that the<strong> Indus-Tsangpo Suture Zone (ITSZ) of <a href="/daily-updates/daily-news-analysis/re-measuring-mount-everest" target="_blank" rel="noopener">Himalaya</a></strong>is<strong> tectonically active.</strong></p>
<ul style="list-style-type: square;">
<li>The suture zone of Himalaya was conventionally thought to be locked.</li>
<li>WIHG is an <strong>autonomous institute</strong> under the <a href="/daily-updates/daily-news-analysis/50th-foundation-day-of-dst" target="_blank" rel="noopener"><strong>Department of Science and Technology</strong> </a>(DST), Government of India.</li>
<li><strong>Tectonics</strong> is the <strong>scientific study of the deformation of the rocks</strong> that make up the Earth&rsquo;s crust and the forces that produce such deformation.<br />
<ul style="list-style-type: circle;">
<li>It deals with the <strong>folding and faulting</strong> associated with mountain building, the large-scale, <strong>gradual upward and downward movements</strong> of the crust and <strong>sudden horizontal displacements</strong> along faults.</li>
</ul>
</li>
</ul>
<h3>Key Points</h3>
<ul style="list-style-type: square;">
<li><strong>Geological Features that Support the Finding:</strong><br />
<ul style="list-style-type: circle;">
<li>Sedimentary beds are tilted and thrust broken.</li>
<li>Rivers are associated with uplifted terraces.</li>
<li>Bedrock shows brittle deformation at much shallower depths.</li>
</ul>
</li>
<li>These deformed geological features were <strong>dated using the technique of Optically Stimulated Luminescence</strong> (OSL) and data of <strong>seismicity</strong> and <strong>denudation rate</strong> was also reviewed.<br />
<ul style="list-style-type: circle;">
<li><strong>Optically-Stimulated Luminescence:</strong> It is a late <strong>quaternary</strong> (geological time period that encompasses the most recent 2.6 million years) dating technique used to date the last time quartz sediment was exposed to light. As sediment is transported by wind, water or ice, it is exposed to sunlight and zeroed of any previous luminescence signal.</li>
<li><strong>Seismicity:</strong> It is the worldwide or local distribution of<a href="/to-the-points/paper1/earthquake-4" target="_blank" rel="noopener"><strong> earthquakes</strong></a> in space, time, and magnitude. More specifically, it refers to the measure of the frequency of earthquakes in a region.</li>
<li><strong><a href="/daily-updates/daily-news-analysis/50th-foundation-day-of-dst">Denudation:</a></strong> It is a long term process in which the wearing and tearing of the surface of the Earth take place. It includes all those processes that lower relief and acts both chemically <strong>(chemical weathering)</strong> and physically <strong>(mechanical weathering).</strong></li>
</ul>
</li>
<li><strong>The region of the ITSZ has been neo-tectonically active since the last 78000-58000 years.</strong><br />
<ul style="list-style-type: circle;">
<li>The ITSZ is a suture zone in the <strong>Ladakh region</strong> and marks the limit of the <strong><a href="/daily-updates/daily-news-analysis/seismicity-study-of-arunachal-himalaya" target="_blank" rel="noopener">Indian plate</a></strong> <strong>where it collides with the Eurasian plate</strong> and is subducted below the latter.</li>
<li>The ITSZ can be traced for<strong> more than 200 km</strong> and a wide variety of rock association along the ITSZ indicates that the collision at the plate boundary was of very <strong>complex nature.</strong></li>
</ul>
</li>
<li>The ITSZ was conventionally believed to be a locked zone till now.</li>
<li>This will have <strong>major implications</strong> in terms of earthquake study, prediction, understanding the seismic structure of the mountain chains well as its evolution.</li>
</ul>
<div class="border-bg">
<p><strong>Suture Zones</strong></p>
<ul style="list-style-type: square;">
<li>A suture zone is a<strong> linear belt of intense deformation,</strong> where distinct terranes, or tectonic units with different plate tectonic, metamorphic, and paleogeographic histories join together.</li>
<li>These zones also <strong>provide the only record of deep oceanic crust and of ancient seafloor processes</strong> for roughly the first 90% of Earth&rsquo;s history.</li>
<li>Their study provides a means to understand the end-product of<strong> plate tectonic processes</strong> in time and space. In plate tectonics, sutures are seen as the remains of subduction zones together with the terranes possibly representing fragments of different tectonic plates.</li>
<li>The suture zone is often <strong>represented on the surface by a mountain range comprising intensely deformed rocks.</strong></li>
<li>The <strong>Iapetus Suture from Great Britain,</strong> which is now concealed beneath younger rocks, and <strong>Indo-Tsangpo Suture</strong> well exposed in the Himalayas are some of the best examples of suture zones.</li>
</ul>
</div>
<p><a href="https://www.pib.gov.in/PressReleasePage.aspx?PRID=1667585" target="_blank" rel="noopener"><strong>Source: PIB</strong></a></p>',
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	(int) 17 => object(Cake\ORM\Entity) {

		'article_id' => (int) 6572,
		'category_id' => (int) 21,
		'title' => 'World Risk Index 2020',
		'description' => '<h3>Why in News</h3>
<p>According to the <strong>World Risk Index (WRI) 2020,</strong> India is &lsquo;poorly prepared&rsquo; to deal with<a href="/daily-updates/daily-news-editorials/challenges-in-climate-change-negotiations" target="_blank" rel="noopener"><strong> &lsquo;climate reality&rsquo;,</strong> </a>due to which it is vulnerable to extreme natural disasters.</p>
<h3>Key Points</h3>
<ul style="list-style-type: square;">
<li><strong>World Risk Index:</strong><br />
<ul style="list-style-type: circle;">
<li>It is calculated on a<strong> country-by-country basis,</strong> through the multiplication of exposure and vulnerability and <strong>describes the disaster risk</strong> for various countries and regions.</li>
<li><strong>Released annually since 2011,</strong> it indicates which countries are in the greatest need to strengthen measures for coping with and adapting to extreme natural events.</li>
<li>It is <strong>part of the World Risk Report 2020</strong> released by the <strong>United Nations University Institute for Environment and Human Security</strong> (UNU-EHS), Bundnis Entwicklung Hilft and the University of Stuttgart in Germany.</li>
<li><strong>Among continents, Oceania is at the highest risk,</strong> followed by Africa and the Americas.</li>
</ul>
</li>
<li><strong>Oceania:<a href="http://www.drishtiias.com/images/uploads/1600940450_image7.jpg" target="_blank" rel="noopener"><img class="content-img" src="http://www.drishtiias.com/images/uploads/1600940450_image7.jpg" style="display: block; margin-left: auto; margin-right: auto;" width="650" caption="false" /></a></strong>
<ul style="list-style-type: circle;">
<li>Small island states, <strong>especially in the South Pacific and the Caribbean,</strong> are disproportionately represented among high-risk countries.<br />
<ul style="list-style-type: disc;">
<li><strong>Vanuatu</strong> (South Pacific Ocean) is the country with the <strong>highest disaster risk worldwide.</strong> It is followed by Tonga (South Pacific Ocean) and Dominica (Caribbean Sea).</li>
</ul>
</li>
<li>They are at a<strong> high exposure to extreme natural events</strong> which include the<a href="/daily-updates/daily-news-analysis/large-population-and-assets-to-be-affected-by-sea-level-rise" target="_blank" rel="noopener"><strong> rise in sea level</strong></a> as a result of <a href="/daily-updates/daily-news-analysis/global-warming-of-1-5-c-ipcc-report" target="_blank" rel="noopener"><strong>global warming.</strong></a></li>
<li>The small island states have <strong>limited financial resources and have made small contributions to climate change,</strong> but are<strong> affected the most</strong> by its consequences.</li>
<li>They are <strong>needed to be compensated for the climate damage and losses</strong> already incurred and merely providing financial resources for adaptation to climate change is not sufficient.</li>
</ul>
</li>
<li><strong>Africa:</strong><br />
<ul style="list-style-type: circle;">
<li>It has been identified as a hotspot of vulnerability<strong>. More than two-thirds of the most vulnerable countries in the world are located on the continent.</strong><br />
<ul style="list-style-type: disc;">
<li>The <strong>size of semiarid regions in Africa is expected to increase,</strong> with over half of Africa&rsquo;s land area <strong>vulnerable to <a href="/to-the-points/paper3/desertification-1" target="_blank" rel="noopener">desertification.</a></strong></li>
<li>Large areas of Africa are<strong> marginalized </strong>and<strong> already under significant financial stress.</strong></li>
</ul>
</li>
<li>The <strong>Central African Republic is the most vulnerable</strong> country, followed by Chad, the Democratic Republic of Congo, Niger and Guinea-Bissau.</li>
</ul>
</li>
<li><strong>South Asia and India:</strong><br />
<ul style="list-style-type: circle;">
<li><strong>India has ranked 89<sup>th</sup> among 181 countries</strong> on the WRI 2020 and is<strong> fourth-most-at-risk in South Asia,</strong> after Bangladesh, Afghanistan and Pakistan.</li>
<li><strong>Sri Lanka, Bhutan and the Maldives have fared better than India</strong> in their <strong>abilities to cope with extreme disasters. India also lags behind </strong>these three neighbours in terms of<strong> lack of adaptive capacities or the preparedness to deal </strong>with extreme events.</li>
<li>A comparison with the WRI 2019, shows tha<strong>t all south Asian countries have slipped</strong> on their <strong>ability to adapt</strong> to the reality of climate emergency.<br />
<ul style="list-style-type: disc;">
<li>Countries with a<strong> score above 52.73, are &lsquo;very poor&rsquo;</strong> in their <strong>adaptive capacities</strong> for extreme natural disasters.</li>
</ul>
</li>
<li><strong>India has also slipped on strengthening adaptive capacities </strong>which is <strong>concerning as it highlights the inability of systems, institutions, and other organisms to adjust</strong> to potential damage, to take advantage of opportunities, or to respond to consequences.<br />
<ul style="list-style-type: disc;">
<li>It becomes more important given that <a href="/daily-updates/daily-news-analysis/assessment-of-climate-change-over-the-indian-region-moes#:~:text=Recently%2C%20the%20first%20Assessment%20of,subcontinent%20in%20the%20coming%20century." target="_blank" rel="noopener"><strong>India's first ever comprehensive climate change assessment report</strong></a> highlighted the impacts of the climate crisis.</li>
</ul>
</li>
</ul>
</li>
</ul>
<p><a href="https://www.downtoearth.org.in/news/climate-change/how-ready-is-india-for-climate-change-not-much-says-this-report-73502" target="_blank" rel="noopener"><strong>Source: DTE</strong></a></p>',
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	(int) 18 => object(Cake\ORM\Entity) {

		'article_id' => (int) 6439,
		'category_id' => (int) 21,
		'title' => 'Typhoon Maysak and Typhoon Haishen',
		'description' => '<p>Why in News</p>
<p>Recently, <strong>Korean Peninsula</strong> and<strong> Japan</strong> were hit by two typhoons named<strong> Maysak</strong> and <strong>Haishen.</strong></p>
<div class="border-bg">
<p><strong>Typhoons</strong></p>
<ul style="list-style-type: square;">
<li>Typhoons are a kind of<strong> storm.</strong> The storms, depending on where they occur, may be called <strong><a href="/daily-updates/daily-news-analysis/hurricane-laura" target="_blank" rel="noopener">hurricanes</a>, typhoons or cyclones.</strong> <br />
<ul style="list-style-type: circle;">
<li><strong>Typhoons:</strong> In the China Sea and Pacific Ocean.</li>
<li><strong>Hurricanes:</strong> In the West Indian islands in the Caribbean Sea and Atlantic Ocean.</li>
<li><strong>Tornados:</strong> In the Guinea lands of West Africa and southern USA.</li>
<li><strong>Willy-willies:</strong> In north-western Australia and</li>
<li><strong>Tropical Cyclones:</strong> In the Indian Ocean Region.</li>
</ul>
</li>
<li>The scientific name for all these kinds of storms is <strong>tropical cyclones.</strong><br />
<ul style="list-style-type: circle;">
<li><strong>Tropical cyclones</strong> are intense circular storms that originate over the warm tropical oceans with speed more than 119 kilometres per hour and heavy rains.</li>
</ul>
</li>
</ul>
<p><a href="http://www.drishtiias.com/images/uploads/1599730742_image6.jpg" target="_blank" rel="noopener"><img class="content-img" src="http://www.drishtiias.com/images/uploads/1599730742_image6.jpg" style="display: block; margin-left: auto; margin-right: auto;" caption="false" width="614" height="328" /></a></p>
</div>
<h3>Key Points</h3>
<ul style="list-style-type: square;">
<li><strong>Categorisation:</strong> Both typhoons were categorised as a <strong>Category 4 hurricane storm.</strong><br />
<ul style="list-style-type: circle;">
<li>A Category 4 storm has <strong>wind speeds between 130-156 mph</strong> and can uproot trees and bring down power lines.</li>
<li>Hurricanes are categorized on the <strong>Saffir-Simpson Hurricane Wind Scale,</strong> which rates them on a scale of 1 to 5 based on wind speed. Hurricanes that reach category <strong>three or higher</strong> are classified as<strong> major hurricanes.</strong></li>
</ul>
</li>
<li><strong>Naming:</strong> The <strong>Maysak</strong> typhoon takes its name from a <strong>Cambodian word</strong> for a type of <strong>tree.</strong> While, Haishen means<strong> sea god</strong> in <strong>Chinese.</strong><br />
<ul style="list-style-type: circle;">
<li>Typhoon Maysak and Haishen are referred to as typhoon number 9 and 10 in Japan.</li>
</ul>
</li>
<li><strong>Background of Naming:</strong><br />
<ul style="list-style-type: circle;">
<li>In <strong>Japan</strong> the first typhoon to occur after January 1<sup>st</sup> of the year is called typhoon number 1.</li>
<li>In the <strong>USA,</strong> hurricanes are referred to by English names.</li>
<li>The intergovernmental organisation called the <strong>Typhoon Committee</strong> which has 14 members including Japan, USA and China uses Asian names for typhoons that are contributed by the member countries. <br />
<ul style="list-style-type: disc;">
<li>Haishen was a name recommended by China, while Maysak is a Combodian name.</li>
</ul>
</li>
</ul>
</li>
</ul>
<p><a href="https://www.thehindu.com/news/international/typhoon-pummels-south-korea-with-flooding/article32510493.ece" target="_blank" rel="noopener"><strong>Source: TH</strong></a></p>',
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		'article_id' => (int) 6333,
		'category_id' => (int) 26,
		'title' => 'Temperature Inversion',
		'description' => '<h3>Meaning</h3>
<ul style="list-style-type: square;">
<li>Under normal conditions, temperature usually decreases with increase in altitude in the troposphere at a rate of 1 degree for every 165 metres. This is called <strong>normal lapse rate.&nbsp;</strong>
<ul style="list-style-type: circle;">
<li>But on some occasions, the situations get reversed and temperature starts increasing with height rather than decreasing. This is called <strong>temperature inversion.</strong></li>
</ul>
</li>
<li><strong>Temperature inversion:</strong> It is a reversal of the normal behavior of temperature in the troposphere. Under this meteorological phenomenon a layer of warm air lies over the cold air layer.<br />
<ul style="list-style-type: circle;">
<li>It is caused in stac atmospheric conditions while some times, it occurs due to <strong>horizontal or vertical movement of air.</strong></li>
<li>Temperature inversion is usually of short duration but quite common nonetheless.</li>
</ul>
</li>
</ul>
<p><a href="http://www.drishtiias.com/images/uploads/1598694790_image4.png" target="_blank" rel="noopener"><img class="content-img" src="http://www.drishtiias.com/images/uploads/1598694790_image4.png" style="display: block; margin-left: auto; margin-right: auto;" caption="false" width="600" height="326" /></a></p>
<h3>Favourable Conditions for Temperature Inversion</h3>
<ul style="list-style-type: square;">
<li><strong>Long winter nights:</strong> Loss of heat by terrestrial radiation from the ground surface during night may exceed the amount of incoming solar radiation.</li>
<li><strong>Cloudless and clear sky</strong>: Loss of heat through terrestrial radiation proceeds more rapidly without any obstruction.</li>
<li><strong>Dry air near the ground surface:</strong> It limits the absorption of the radiated heat from the Earth&rsquo;s surface.</li>
<li><strong>Slow movement of air:</strong> It results in no transfer or mixing of heat in the lower layers of the atmosphere.</li>
<li><strong>Snow covered ground surface:</strong> It results in maximum loss of heat through reflection of incoming solar radiation.</li>
</ul>
<h3>Types of Temperature Inversion</h3>
<ul style="list-style-type: square;">
<li>Temperature inversion occurs in several conditions ranging from ground surface to great heights. Thus there are several kinds of temperature inversions. </li>
<li>The following are classified on the basis of relative heights from the earth&rsquo;s surface at which it occurs and the type of air circulation:</li>
<li><strong>Non-Advectional</strong><br />
<ul style="list-style-type: circle;">
<li><strong>Radiation Inversion (Surface Temperature Inversion)</strong><br />
<ul style="list-style-type: disc;">
<li>Surface temperature inversion develops when air is cooled by contact with a colder surface until it becomes cooler than the overlying atmosphere; this occurs most often on clear nights, when the ground cools off rapidly by radiation. If the temperature of surface air drops below its dew point, fog may result. </li>
<li>It is very common in the higher latitudes. In lower and middle latitudes, it occurs during cold nights and gets destroyed during day time.<a href="http://www.drishtiias.com/images/uploads/1598694827_image1.jpg" target="_blank" rel="noopener"><img class="content-img" src="http://www.drishtiias.com/images/uploads/1598694827_image1.jpg" style="display: block; margin-left: auto; margin-right: auto;" caption="false" width="600" height="402" /></a></li>
</ul>
</li>
<li><strong>Subsidence Inversion (Upper Surface Temperature Inversion)</strong><br />
<ul style="list-style-type: disc;">
<li>When a widespread layer of air descends, it is compressed and heated by the resulting increase in atmospheric pressure, and as a result the lapse rate of temperature is reduced.</li>
<li>The air at higher altitudes becomes warmer than at lower altitudes, producing a temperature inversion. This type of temperature inversion is called subsidence inversion.</li>
<li>It is very common over the northern continents in winter (dry atmosphere) and over the subtropical oceans; these regions generally have subsiding air because they are located under large high-pressure centers.</li>
<li>It is also called upper surface temperature inversion because it takes place in the upper parts of the atmosphere.</li>
</ul>
</li>
</ul>
</li>
</ul>
<p><a href="http://www.drishtiias.com/images/uploads/1598694848_image2.jpg" target="_blank" rel="noopener"><img class="content-img" src="http://www.drishtiias.com/images/uploads/1598694848_image2.jpg" style="display: block; margin-left: auto; margin-right: auto;" caption="false" width="450" height="343" /></a></p>
<ul style="list-style-type: square;">
<li><strong>Advectional</strong><br />
<ul style="list-style-type: circle;">
<li><strong>Valley inversion in intermontane valley</strong><br />
<ul style="list-style-type: disc;">
<li>In high mountains or deep valleys, sometimes, the temperature of the lower layers of air increases instead of decreasing with elevation along a sloping surface.</li>
<li>Here, the surface radiates heat back to space rapidly and cools down at a faster rate than the upper layers. As a result the lower cold layers get condensed and become heavy.</li>
<li>The sloping surface underneath makes them move towards the bottom where the cold layer settles down as a zone of low temperature while the upper layers are relatively warmer.</li>
<li>This condition, opposite to normal vertical distribution of temperature, is known as Temperature Inversion.<a href="http://www.drishtiias.com/images/uploads/1598694867_image5.jpg" target="_blank" rel="noopener"><img class="content-img" src="http://www.drishtiias.com/images/uploads/1598694867_image5.jpg" style="display: block; margin-left: auto; margin-right: auto;" caption="false" width="400" height="200" /></a></li>
</ul>
</li>
<li><strong>Frontal or Cyclonic inversion</strong><br />
<ul style="list-style-type: disc;">
<li>When the warm and cold fronts meet, then the warm front rises up and being heavier the cold front sinks down. It results in formation of Frontal Inversion.</li>
<li>It has considerable slope, whereas other inversions are nearly horizontal. It often takes place in the temperate zone and causes cyclonic conditions which result in the precipitation in different forms.</li>
<li>A frontal inversion is unstable and is destroyed as the weather changes.</li>
</ul>
</li>
</ul>
</li>
</ul>
<p><a href="http://www.drishtiias.com/images/uploads/1598694888_image3.png" target="_blank" rel="noopener"><img class="content-img" src="http://www.drishtiias.com/images/uploads/1598694888_image3.png" style="display: block; margin-left: auto; margin-right: auto;" caption="false" width="600" height="432" /></a></p>
<h3>Effect</h3>
<ul style="list-style-type: square;">
<li>Temperature inversion determines the precipitation, forms of clouds, and also causes frost due to condensation of warm air due to its cooling.<br />
<ul style="list-style-type: circle;">
<li><strong>Dust particles hanging in the air:</strong> Due to inversion of temperature, air pollutants such as dust particles and smoke do not disperse on the surface.</li>
<li><strong>Stops the movement of air:</strong> It causes the stability of the atmosphere that stops the downward and upward movement of air.</li>
<li><strong>Less rainfall:</strong> Convection clouds can not move high upwards so there is less rainfall and no showers. So, it causes a problem for agricultural productivity.</li>
<li><strong>Lower visibility:</strong> Fog is formed due to the situation of warm air above and cold air below, and hence visibility is reduced which causes disturbance in transportation.</li>
<li><strong>Thunderstorms and tornadoes:</strong> Intense thunderstorms and tornadoes are also associated with inversion of temperature because of the intense energy that is released after an inversion blocks an area&rsquo;s normal convention patterns.</li>
<li>Diurnal variations in temperature tend to be very <strong>small.</strong></li>
</ul>
</li>
</ul>',
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