A strong breeze under an overcast sky gifted Calcuttans an untimely chill on the last morning of February.
Around 7am on Friday, the wind was blowing at 10kmph, which meteorologists said made the prevalent temperature of 20 degrees Celsius seem much lower.
The conditions changed dramatically after the sun was out by 10pm and the wind speed decreased before picking up again in the afternoon.
At 8.30am, the wind was blowing at 8kmph. The speed fell to 4kmph around 2.30pm, only to rise to 6kmph around 5.30pm (see chart).
Rain in the western districts caused the breeze, the weather office said. “The cool breeze will continue on Saturday and the sky will be partly cloudy. There is a possibility of rain in western Bengal but not in Calcutta,” said Gokul Chandra Debnath, the director of India Meteorological Department, Calcutta.
“I was hit by a chilly gust the moment I stepped out around 7.15am. I lifted my son in my arms and rushed in lest he catches a cold. We put on some woolens and then left,” said Behala resident Tanima Mondal, 39, recounting her experience while leaving home to drop her son at school.
Rain in neighbouring states, as well as some Bengal districts — such as Bankura, Burdwan, Hooghly, Murshidabad, Nadia and Purulia — caused the strong breeze.
When it rains, the temperature in the area comes down and consequently the air pressure rises.
Following the rain in districts to the west of Calcutta, the temperature dropped and the air pressure rose. “The rise in air pressure following the rain caused cold wind from west and north-west to rush to Calcutta, where the pressure remained low because of lack of rain. As the day progressed, the air pressure stabilised and the wind subsided. But in the evening it again started raining to the west of Calcutta and the breeze gained speed,” said a weather scientist.
Debnath said there is no wind system in and around Calcutta at the moment as a high-pressure belt and a cyclonic circulation that were active till the middle of the week have dissipated.
“The wind and pressure conditions in Gangetic Bengal, which is close to the Bay of Bengal, are such that the thunderstorms are not travelling till Calcutta,” said a weather scientist.