Weather
Weather and climate experts explain the reasons why Kerala and Tamil Nadu are experiencing cold nights and hot days.

Early mornings became suddenly cold when New Year struck. The normally moderate, not-too-hot-never-too-cold weather of Kerala became “chilling” for its people unused to such extremes, and the days, terribly hot. Chennai has been making the same complaint, Hyderabad too has seen a steep drop in temperature. Munnar, a hill station in Kerala has had sub-zero temperature in the last few days.

While normally indifferent to most changes outside the concern of their daily lives, Malayalis woke up to cold mornings with a slight shiver, not just because of the unusual temperatures, but because of the all-too-fresh memories of a flood that went by, wrecking the state so much. A change in climate could not be blinked away and ignored anymore. It had to be investigated.

“It is because the polar vortex has weakened and this causes cold air to blow towards our part of the world. Another reason is caused by the western disturbance coming from the North West as a wave towards the East – towards India,” says Dr Abhilash S, Asst Professor, Department of Atmospheric Sciences, CUSAT.

He says that this weather is common in the northern part of the country; it is just new in the south. “What happens is humidity and clouds would not be there, and this causes the temperatures to be extreme during day and night. So in the night time, there would not be humidity to hold the heat of the sun – humidity works like a greenhouse gas. And in the day, you get hit by direct sunlight because it is a cloudless sky,” Abhilash adds.

That explains the minus degree temperatures in Munnar. On January 7, the variations in minimum and maximum temperatures across the state showed noticeable departures. While the maximum temperatures are between 30 and 33 degree Celsius, the minimum varies from 18 to 25 degree Celsius.

The variations appear all over south India. “It is because of the high pressure that is common at this time of the year over the Indian peninsula. The moisture content is zero, there is no humidity. So whatever heat comes to us is reflected back,” says Pradeep John, weatherman, Tamil Nadu. It has nothing to do with global warming, he assures us.

Abhilash agrees that there is no direct connection to global warming. “But indirectly, global warming may result in the phenomenon extending further,” he says.

On his Facebook page, Tamil Nadu Weatherman, Pradeep records on January 5: “With Jet stream expected to dip again and then with High pressure expected to dominate the Indian peninsula. The cold days are expected to continue in interior Tamil Nadu. Bangalore, Mysuru too will be colder than normal.”