New Delhi | Jagran News Desk: The India Meteorological Department has warned that a cold wave is likely over some parts of Punjab, Haryana, and northern Rajasthan in the next two days, starting Tuesday, November 23. This comes as temperatures are about to dip from Tuesday. It will be the first cold wave of this season. Usually, the weather office declares a cold wave when the minimum temperature drops below 10 degrees Celsius or is 4.5 degrees lower than the season’s normal for two straight days. A cold wave is also declared when the minimum temperature is less than 4 degrees in the plains.

“Minimum temperatures are likely to dip in Delhi but the cold wave is not likely. Cold wave may be recorded in Haryana and Punjab,” said RK Jenamani, senior scientist at the IMD, while speaking to media. “In rural pockets, cold wave conditions are likely to set in,” he added.

The minimum temperature in Delhi fell to 9.6 degrees on November 17, and 9.8 degrees on Sunday, 3 degrees below normal on both instances. On Monday, the minimum temperature was 11.4 degrees while Haryana's Hisar recorded 7.2 degrees, 4 degrees below normal.

Further, IMD has predicted moderate to heavy rainfall over Karnataka, Kerala, Mahe, Tamil Nadu, Puducherry, and Karaikal during the next five days. This comes as a cyclonic circulation is lying over the southeast Bay of Bengal and its neighbourhood in the lower tropospheric. It is likely to move west-northwestward towards the Tamil Nadu coast in the next 4-5 days.

Why do temperatures fall?

“There are two ways by which the temperature falls. One is a clear sky, which leads to the warmth radiating back quickly from the surface. It’s called radiational cooling. There are clear skies over northwest India now,” explained DS Pai, scientist and head of climate research and services at IMD Pune.

“The other reason for cold setting in is that northwesterly cold and dry winds are blowing over the region from the Himalayas. There is a low-pressure area over the Arabian Sea which also indirectly helps in the incursion of northwesterly winds over the entire northwestern region. This happens during winter. Consecutive low-pressure areas have formed over the Arabian Sea,” he added.

Posted By: Sugandha Jha