Darkness descended on Calcutta on Friday afternoon with black clouds hanging low but the rain that followed was far from being a monsoon downpour, in keeping with the season’s trend. “The city will receive rain for the next three-four days,” said Gokul Chandra Debnath, the director of the Alipore Met office. The cloud build-up (in picture by Bishwarup Dutta, taken from the approach to Vidyasagar Setu from the city) resulted from a cyclonic circulation over coastal Bengal and Bangladesh that has been sucking moisture from the Bay. The circulation is likely to move inland and boost rainfall activity in Calcutta and other parts of south Bengal over the next few days. The monsoon trough is near Digha on the Bengal-Odisha border. Weather scientists said Calcutta would have received heavier rainfall had the trough passed closer to the city while the cyclonic circulation was still active. The Met office said north Calcutta received more rain than south and Salt Lake on Friday. Dum Dum received 41.9mm of rain, and Alipore and Salt Lake, 20.1mm and 7mm, respectively. “This sort of skewed distribution is typical of rain triggered by a cyclonic circulation,” said Debnath.