Calcutta’s north-south divide is complete, even the rain gods now treat the two parts of the city differently.
A cloudy build-up to Wednesday resulted in a drizzle in the south and a downpour in the north, the gap in the quantum of rain received over the same period reflecting the meteorological discrimination.
Alipore received 7.6mm of rain between 12.30pm and 2pm, while Salt Lake recorded 58mm and Barrackpore 60mm. The Met office considers 58mm in one-and-a-half hours to be heavy rain. The last time Calcutta received that much rain, it was over an entire day.
“It is unusual to have such a stark difference in rain over north and south Calcutta during monsoon. Generally, we have homogeneous rain because clouds form over a large area during the rainy season,” said Gokul Chandra Debnath, the director of the Alipore Meteorological Centre.
Wednesday’s rain in the city and its suburbs was caused by localised thunderclouds, the character of which differed in various locations, Debnath pointed out.
Rain at this time of the year is usually triggered by clouds formed by the accumulation of moisture brought inland from the Bay of Bengal by monsoon winds.
“There is a cyclonic circulation over the Bay of Bengal and Gangetic West Bengal. This led to incursion of moisture from the Bay of Bengal and the formation of localised thunderclouds of different rain-bearing capacity over different parts of town,” Debnath said.
The disparity in rain over north and south Calcutta on Wednesday took many by surprise. “I was shocked to find knee-deep water around Central Avenue at 3pm after passing through an almost dry Hazra, which is otherwise prone to flooding. Then someone told me how heavily it had rained in north Calcutta,” said trader Diptangshu Mitra.
At Dum Dum, visibility was so low that six incoming flights were forced to postpone landing. Flight services were disrupted between 12 and 1pm.