Walkers on a fog-engulfed Maidan around 6.30am on Friday. (Sayantan Ghosh)
Calcutta on Friday woke up to a foggy screen that belied the time of the day and ushered in a hill station feel minus the chill.
The fog which kept many in bed longer than usual hung over the city well into the morning, almost till noon in some pockets, in the absence of a strong wind.
The weatherman attributed the fog to an abundance of moisture in the atmosphere, which is also keeping the chill at bay by blocking the cold North Wind.
The Met office expects the temperature to come down gradually from Sunday, though the “real cold feeling” is unlikely to be experienced before Tuesday.
“The minimum temperature, which shot up six notches above normal to 20.9 degrees Celsius on Friday, may climb down to 15 by Monday, which is normal around this time. After that it should fall again by a degree or two,” said Gokul Chandra Debnath, director, India Meteorological Department, Calcutta.
Debnath said a high-pressure belt over the Bay of Bengal and near the Bengal coast had stepped up the flow of moisture from the see, resulting in the fog.
The weather system has moved inland and weakened but left enough humidity in the air to cause fog on Saturday as well.
Experts say fog occurs when the air becomes saturated with moisture and the temperature is less than the dew point — the temperature at which water vapour in a volume of humid air condenses into water.
“Higher the temperature, higher the capacity of the air to hold water vapour. So when the temperature drops, at dawn or in the evening, there tends to be fog,” said a weather department official.
The fog threw the working-day schedule of many Calcuttans out of gear. “I was late today because of the weather. When I got up thinking it must be around 7.30am, it was actually close to 9am,” said Ballygunge resident Antara Mitra.
“It was still foggy when I left home for office an hour later. But I can’t complain, the weather was in one word beautiful. It was a bit like Darjeeling but it wasn’t cold at all,” she gushed.
For the same reason, there were lesser number of morning walkers on the Maidan and generally lesser number of people about the street.
Fog, of course, generally happens in places that are close to water bodies. Calcutta, of course, is a prime candidate as being close to the Bay of Bengal.
The fog, however, was not very dense as the high pressure belt that was behind the incursion of moisture, has moved inland.
Meteorologists said the despite the incursion having stopped, the fog stayed for a long time because there was no wind that would blow it away.
The minimum temperature, however, rose by over two degrees Celsius to reach 20.9, a good six notches above normal, with the northerly wind — which brings the cold into the city — being blocked because of the moisture. This is the highest the minimum temperature has been since November 21, when the recording was 21.7 degrees Celsius.
The maximum temperature also rose but ever so slightly, recording 27 degrees Celsius, which is normal for this time of the year.
But, simultaneously, the high pressure belt is likely to move further inland and reach near Jharkhand. Once that happens, around early next week, this same system that was keeping things warm in the region, would start pulling the northerly wind and make things pretty cold.