Report on Lightning Strikes

• 04 Jan 2021

Why in News

According to a report published by the Climate Resilient Observing Systems Promotion Council (CROPC), the number of deaths due to lightning strikes reduced by nearly 37% in 2019-20.

• CROPC is a non-profit organisation that works with the India Meteorological Department (IMD).

Key Points

• Data Analysis:
  
  • Lightning-linked fatalities formed 33% of total deaths in natural disasters in 2019-20.
• Factors Responsible:
  
  • The rapid degradation of environment like global warming, deforestation, depletion of water bodies, concretisations, rising pollution and aerosol levels have cumulatively pushed the environment to extremes. And lightning is direct promulgation of these climatic extremities.
• Suggestions:
  
  • States should participate in Lightning Resilient India Campaign and undertake lightning risk management more comprehensively.
    
    • IMD has launched a joint campaign named Lightning Resilient India Campaign along with CROPC and duly supported by Indian Meteorological Society (IMS), NGOs, IIT Delhi and other concerned institutions.
  • Early lightning warning to farmers, cattle grazers, children and people in open areas.
    
    • Lightning strikes around a fixed period and almost similar geographical locations in similar patterns.
    • Kalbaishakhi - Norwesters, which are violent thunderstorms with lightning - claims life in eastern India and pre-monsoon lightning deaths occur mostly in Bihar, Jharkhand, Chhattisgarh and UP.
  • Implement a local lightning safety action plan like installing Lightning Protection Devices.
  • Lightning fatalities should be notified as a disaster to prevent losses.
    
    • It needs to be noted that the Centre has not notified lightning as a disaster.
  • Although the National Disaster Management Authority (NDMA) has issued comprehensive guidelines for action plans to states, a large number of losses show that the implementation needs a more “scientific and focused community-centric approach”, besides convergence of various departments.
  • Mapping of lightning is a major breakthrough in identifying the precise risk in terms of lightning frequency, current intensity, energy content, high temperature and other adverse impacts.
    
    • With continuous mapping for at least three years, a climatology can be established. This would yield a Lightning Risk Atlas map for India which will form the basis for a lightning risk management programme.

Lightning

• Meaning:
  
  • It is a very rapid and massive discharge of electricity in the atmosphere. It is the process of occurrence of a natural ‘electrical discharge of very short duration and high voltage between a cloud and the ground or within a cloud’, accompanied by a bright flash and sound, and sometimes thunderstorms.
  • Inter cloud or intra cloud (IC) lightning are visible and harmless.
  • It is cloud to ground (CG) lightning, which is harmful as the ‘high electric voltage and electric current’ leads to electrocution.
• Process:
  
  • It is a result of the difference in electrical charge between the top and bottom of a cloud.
    
    • The lightning-generating clouds are typically about 10-12 km in height, with their base about 1-2 km from the Earth’s surface. The temperatures at the top range from -35°C to -45°C.
  • As water vapour moves upwards in the cloud, it condenses into water due to decreasing temperatures. A huge amount of heat is generated in the process, pushing the water molecules further up.
  • As they move to temperatures below zero, droplets change into small ice crystals. As they continue upwards, they gather mass, until they become so heavy that they start descending.
  • It leads to a system where smaller ice crystals move upwards while larger ones come down. The resulting collisions trigger release of electrons, in a process very similar to the generation of electric sparks. The moving free electrons cause more collisions and more electrons leading to a chain reaction.
  • The process results in a situation in which the top layer of the cloud gets positively charged while the middle layer is negatively charged.
  • In little time, a huge current, of the order of lakhs to millions of amperes, starts to flow between the layers.
    
    • It produces heat, leading to the heating of the air column between the two layers of cloud.
    • It is because of this heat that the air column looks red during lightning.
    • The heated air column expands and produces shock waves that result in thunder sounds.
• Strikes Earth’s Surface:
  
  • The Earth is a good conductor of electricity. While electrically neutral, it is relatively positively charged compared to the middle layer of the cloud. As a result, an estimated 20-25% of the current flow is directed towards the Earth.
    
    • It is this current flow that results in damage to life and property.
  • Lightning has a greater probability of striking raised objects on the ground, such as trees or buildings.
    
    • Lightning Conductor is a device used to protect buildings from the effect of lightning. A metallic rod, taller than the building, is installed in the walls of the building during its construction.
  • The most lightning activity on Earth is seen on the shore of Lake Maracaibo in Venezuela.
    • At the place where the Catatumbo river falls into Lake Maracaibo, an average 260 storm days occur every year, and October sees 28 lightning flashes every minute - a phenomenon referred to as the Beacon of Maracaibo or the Everlasting Storm.

Concretisation

• Concretisation or the increase in paved surfaces has a suffocating impact on trees and turns a city into an urban heat island with extremely low ground water and threats of floods looming large in monsoons due to surface run-off.
  
  • The concrete surface, be it buildings or roads or footpaths radiate heat waves in the evening, making nights as hot as days and decreasing the difference between the maximum and the minimum temperatures, resulting in urban heat island effect.
• During concretisation, the carbon stored in the soil escapes into the atmosphere, which then gets oxidised to form carbon dioxide, a major greenhouse gas leading to temperature escalation.

Source: IE