Heat Waves

• 26 May 2020

Why in News

Recently, the India Meteorological Department (IMD) has forecasted the “heatwave to severe heatwave conditions” over northwest, central and adjoining peninsular India along with heavy rain over northeast India.

• Many parts of coastal Andhra Pradesh, Odisha and Maharashtra have also observed increase in temperatures above 42°C, triggering heatwave conditions.
• The heat wave has been observed due to dry northwesterly winds prevailing over northwest and central India.

India Meteorological Department

• The India Meteorological Department (IMD) was established in 1875.
• It is an agency of the Ministry of Earth Sciences of the Government of India.
• It is the principal agency responsible for meteorological observations, weather forecasting and seismology.

Heat Wave

• A heat wave is a period of abnormally high temperatures, more than the normal maximum temperature that occurs during the summer season in the North-Western and South Central parts of India.
• Heat waves typically occur between March and June, and in some rare cases even extend till July.
• Higher daily peak temperatures and longer, more intense heat waves are becoming increasingly frequent globally due to climate change.

Criteria for Heat Waves

• The heat wave is considered when the maximum temperature of a station reaches at least 40°C for Plains and at least 30°C for Hilly regions.
• If the normal maximum temperature of a station is less than or equal to 40°C, then an increase of 5°C to 6°C from the normal temperature is considered to be heat wave condition.
  
  • Further, an increase of 7°C or more from the normal temperature is considered as severe heat wave condition.
• If the normal maximum temperature of a station is more than 40°C, then an increase of 4°C to 5°C from the normal temperature is considered to be heat wave condition. Further, an increase of 6°C or more is considered as severe heat wave condition.
• Additionally, if the actual maximum temperature remains 45°C or more irrespective of normal maximum temperature, a heat wave is declared.

Health Impacts of Heat Waves

• The health impacts of Heat Waves typically involve dehydration, heat cramps, heat exhaustion and/or heat stroke.
• It also causes heat cramps, fatigue, weakness, dizziness, headache, nausea, vomiting, muscle cramps and sweating.
• The extreme temperatures and resultant atmospheric conditions adversely affect people living in these regions as they cause physiological stress, sometimes resulting in death.

Way Forward

• While climate change does have a strong link with the occurrence of extreme weather events, it isn't the cause for extreme weather events. Episodes of heat waves are growing more common as climate change intensifies. Therefore, the intensity and frequency of heatwaves can be reduced if the global community adopts and adheres to a lower emissions scenario in the future.

Source:TH