Updated: March 22, 2022 8:32:14 am
New Delhi (Sardurjung) recorded a temperature of over 38 degrees Celsius on Sunday, the hottest for March so far for the national capital. Jammu and Uttarakhand reported heatwaves for a brief period last week. Rajasthan is reeling under a heatwave for nearly a week now. Why is it so hot over north and northwest India in March?
As winter transitions to spring with the northward march of the Sun post the winter solstice, maximum temperatures in India show a rising trend, starting from southern parts followed by central and northern India.
March is the beginning of the summer season over India. During this month, the maximum heating zone runs along central India regions between Odisha and Gujarat. Here, hotter conditions start building up in March.
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The maximum temperatures peak in April and May and the India Meteorological Department (IMD) identifies the core heatwave zone spanning Rajasthan, Punjab, Haryana, Chandigarh, Delhi, West Madhya Pradesh, Uttar Pradesh, Chhattisgarh, Odhisha, Vidarbha in Maharashtra, parts of Gangetic West Bengal, Coastal Andhra Pradesh and Telangana.
Hot winds from the deserts of northwest India also contribute to the soaring temperatures in central India regions.
Many places in the northwest and cities along the southeastern coast report up to eight heatwave days per season. However, the regions in the extreme north, northeast and southwestern India are lesser prone to heatwaves.
This year, the geographical expanse of the latest heatwave spell was unusually large.
North and northwest India including Jammu, Kutch-Sauratshtra, Rajasthan along with parts Madhya Pradesh and Uttarakhand experienced heatwave last week.
In addition to such a large area being under the influence of heatwaves, the latest spell was a prolonged one too. It later spread to Gujarat, north Maharashtra and extended all the way to interior Odisha.
“During the past few days, the southerly winds from Gujarat, south Pakistan took the heat to southern and southwest Rajasthan. There were no active western disturbances, which otherwise brings colder winds. As a result, temperatures in Jammu, Rajasthan and neighbourhood areas remained higher than normal,” said Mrutyunjay Mohapatra, director general, IMD.
Missing rain and thunderstorms
Along with seasonal transition, the lack of pre-monsoon showers has contributed to the overall heating.
“There has not been significant thunderstorm activity and associated rainfall over most parts of the country in March,” said Dr Mohapatra.
The cumulative effect is an all India March (till March 21) rain deficit at 83 per cent. So far, surplus rain was recorded only over Kerala (14 per cent) and Andaman and Nicobar Islands (599 per cent), all other states and Union Territories have remained dry.
The Andamans are presently bracing for Cyclone Asani and high rainfall is mainly associated with the storm.
Region-wise rainfall over India in March (March 1 to 21, IMD data)
1) Northwest India: minus 86 per cent
2) East and northeast India: minus 92 per cent
3) Central India: minus 84 per cent
4) South Peninsula: minus 40 per cent
Heatwave in Antarctica
On March 18, surface air temperature recorded along eastern Antarctica were historic — up to 40 degrees Celsius above normal.
Normally, the temperatures around this time of the year should have been around minus 45 to minus 50 degrees Celsius. However, the southern pole recorded somewhere between minus 18 and minus 12 degrees, which climate scientists are terming unprecedented.
Last week, Concordia, a station located on the Antarctica plateau and at a distance of 1,670 km from the Geographic South, reported temperatures 50 degrees above normal. The situation has arisen due to warm westerly winds surpassing the Southern Ocean and reaching the interior parts of Antarctica.
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