HEATWAVE (Syllabus: GS Paper 1/3 – Geography/Disaster)
Context: Recently, the Meteorological Department (IMD) issued heatwave warnings, urging caution, as Delhi reached a record-breaking temperature of 52.3 degrees Celsius.
Heatwave
- Meaning: It is a period of abnormally high temperatures, more than the normal maximum temperature that occurs during the summer season in the North-Western parts of India.
- Conditions for Declaring a Heatwave: When the temperature exceeds 40°C in the plains or 37°C in coastal regions.
o if the temperature is 4.5°C above the normal temperature.
- Duration and Consistency: The declaration requires at least two consecutive days of these extreme temperatures.
- At least two weather stations in a sub-division must record such temperatures.
- Severe Heatwave Criteria: The temperature must exceed the normal by 6°C.
- Causes:
o El Nino's Influence: One significant factor contributing to heatwaves is the El Nino weather pattern, characterized by abnormal warming of waters in the equatorial Pacific Ocean.
o High-Pressure Systems: Another factor contributing to heatwaves is the presence of high-pressure systems over the Southern peninsula and South-Eastern coastal areas.
o Atmospheric Dynamics: These high-pressure systems push warm air closer to the Earth's surface, intensifying heat levels and hindering the incoming sea breeze that typically cools the land.
o Cumulative Effects: The combined influence of El Nino and high-pressure systems creates a potent environment conducive to prolonged heatwaves and extreme heat events.
- Duration of heatwaves: Earlier, heatwaves used to last four to eight days.
o In the last two years alone, India has seen an unprecedented 328 heatwave days.
o 2023 was the hottest year on record.
- India’s Initiative: India’s first heatwave action plan was developed three years after a heatwave claimed 800 lives in Ahmedabad in May 2010.
o It involved setting up an early warning system, improving the healthcare system and creating awareness.
