April 22, 2024
Introduction:
An intense heat wave swept across large swathes of the country, with maximum temperatures settling four to six degrees Celsius above normal in many areas.
Second Heat Wave Spell of April
This ongoing heat wave is the second spell this month, with the first one having scorched parts of Odisha, Jharkhand, Gangetic West Bengal, Telangana, Andhra Pradesh, Tamil Nadu and Gujarat. Some of the highest maximum temperatures recorded, included 46°C in Bahargora, Jharkhand, 44.6°C in Baripada, Odisha, 44.5°C in Bankura, West Bengal, 44°C in Bulandshahr, Uttar Pradesh, and 43.6°C in Washim, Vidarbha.
What is heat wave?
Heat wave is a condition of air temperature which becomes fatal to human body when exposed. Quantitatively, it is defined based on the temperature thresholds over a region in terms of actual temperature or its departure from normal. In certain countries it is defined in term of the heat index based on temperature and humidity or based on extreme percentile of the temperatures.
Criteria for Heat Waves
- The IMD declares a heat wave when the maximum temperature reaches at least 40°C in the plains, 37°C in coastal areas, and 30°C in hilly regions, with the departure from normal being at least 4.5°C.
- A severe heat wave is declared if the departure exceeds 6.4°C.
Concerns During Lok Sabha Elections
- The IMD had earlier warned of extreme heat during the April-June period, coinciding with the seven-phase Lok Sabha elections in which around a billion people are expected to vote.
- This has heightened concerns about vulnerability to heat waves.
- The first phase of voting took place recently.
Predictions for April-June Period
- The IMD predicts four to eight heat wave days in different parts of the country in April, against a normal of one to three days.
- For the entire April-June period, 10 to 20 heat wave days are expected, compared to the normal four to eight days.
- Madhya Pradesh, Gujarat, Odisha, Andhra Pradesh, Madhya Maharashtra, Vidarbha, Marathwada, Bihar and Jharkhand are likely to witness a higher number of heat wave days, with some places possibly recording more than 20 such days.
Potential Impacts of Heat Wave in India
- The intense heat could strain power grids and lead to water shortages in parts of India.
- Global weather agencies, including the IMD, are also expecting La Niña conditions to develop later in the year.
- El Niño conditions, associated with weaker monsoon winds and drier conditions in the country, are currently prevailing but weakening.
- La Niña conditions, which are the opposite of El Niño, typically lead to abundant rainfall during the monsoon season.
About The India Meteorological Department (IMD)
- Established in 1875
- National meteorological service of India
- Headquartered in New Delhi
- Responsible for meteorological observations, weather forecasting, and seismology
- Operates hundreds of observation stations across India and Antarctica
- Regional offices in Mumbai, Chennai, Kolkata, Nagpur, Guwahati, and New Delhi
- Specialised divisions for agrimet, hydromet, instruments, and training
- Collaborates with international organizations like WMO
- Played a crucial role in providing timely warnings during cyclones like Phailin, Hudhud, and Fani
The IMD reported that maximum temperatures hovered between 42 and 45 degrees Celsius in parts of Odisha, Rayalaseema, Gangetic West Bengal, Jharkhand, Vidarbha, Chhattisgarh, Madhya Pradesh, Telangana and Andhra Pradesh.
Parts of Bihar, Madhya Pradesh, Tamil Nadu, Puducherry and Uttar Pradesh recorded maximum temperatures between 40 and 42 degrees Celsius.