It’s been one of the driest winter-springs in recent memory, for West Bengal. So when the sky became overcast last week and Kolkata’s evening breeze strengthened into a stiff wind causing eddies of fallen leaves and dust devils, there was a thrill of expectation. Lightning flashed, twigs snapped and suddenly there was a sharp downpour. It was Kalboishakhi time again, when nor’wester storms furiously race to the Ganga delta from the Chhotanagpur