On the cold pools and their role in the development of nor’westers over West Bengal and Eastern Pakistan

Abstract

In two recent notes Ramaswamy and Bose (1953a, 1953b) have put forward the view that "advection of colder air between 10,000 and 20,000 ft and possibly also bet-ween 20,000 and 30,000 ft appears to be the _final determining factor in the outbreak of nor'westers, at least when they are wide-spread ". According to them in every one of the seven cases of nor'westers studied in the first note there was a cold pool or trough on the 700-500 nib thickness charts, 18-24 hours before the outbreak of nor'westers which tended to be maximum in the sector where thermal winds were from SSE and WSW. It is also stated that in some of those cases studied, there were few indica-tions in the charts for sea level or upper levels below 10,000 ft to suggest the deve-lopment of nor'westers.