Relax, there is no heat wave in Tamil Nadu

Meteorologists say the easterlies (wind blowing from east) bringing moisture and the cloud cover over Tamil Nadu are saving it from the harsh heat wave.

A flock of ducks on the Cholavaram reservoir, which is one of the primary source for city’s drinking water. It has hardly any water left to meet the rising summer demand | D SAMPATHKUMAR

CHENNAI: You may be complaining about the hot summer. But the weathermen say Tamil Nadu has been enjoying a much pleasant weather compared to the central and northern states where a heat wave is breaching the 43 degree Celsius mark consistently.

In contrast, Chennai’s maximum temperature has not yet crossed even the 35-degree Celsius. Why? Meteorologists say the easterlies (wind blowing from east) bringing moisture and the cloud cover over Tamil Nadu are saving it from the harsh heat wave.

“The clouds and easterlies have saved Tamil Nadu and some of the other southern parts from heat wave,” says D S Pai, head, climate prediction, Climate Research Division of Indian Meteorological Department.

The only place in Tamil Nadu that has so far recorded a temperature more than 40 degree Celsius is Karur. On Thursday, the Nungambakkam weather station at Chennai recorded a maximum of 33.7 degrees.

Meteorologists explain that the cause of heat waves sweeping central and northwest parts was strong high pressure system. The INSAT-3D satellite imagery, which is used by the Indian Meteorological Department (IMD) to forecast Outgoing Longwave Radiation (OLR) clearing, shows that the system is concentrated over central and northwestern parts and spared southern region, especially Tamil Nadu.

Pradeep John, a famous weather blogger, said the heat wave occurs when a system of high atmospheric pressure moves into an area. In such a high pressure system, air from upper levels of our atmosphere is pulled toward the ground, where it becomes compressed and increases temperature.

It also prevents clouds from entering the region; sunlight can become punishing, heating up the system even more. All of these factors come together to create the exceptionally hot temperature that we call a heat wave.

S Balachandran, director, Area Cyclone Warning Centre, told Express there is not just one factor that induces heat wave-like conditions.

“The wind direction, clear sky, moisture, geographical dynamics etc., have their influence. In terms of climatology, Tamil Nadu doesn’t fall in heat wave-prone regions. Only in April and May, temperatures briefly breach 40 degrees Celsius. Otherwise by and large they remain normal. Of course, there were instances in the past where heat wave-like conditions prevailed, but there is no such condition this year,” he said and added that till April first week, the climate will remain dry.