Bay of Bengal Monsoon

Abstract

Synoptic charts for 00 and 12 GMT for 1 and 2 June 1963 have been examined and it is observed that there was no cyclone at. 11⁰N, Long, 95°E at 00 GMT on 2 June as indicated by Ramage (1963, 1964) in his 500-mb stream lines chart, There could only be a short-lived vortex of small extent near the boundary of the fresh monsoon air; such a vortex was present both at 700 and 500 mb as shown by aircraft reports. It is shown that to use data of dropsoundings for the lst when there was no cyclone, to determine structure of the so-called cyclone in existence on the 2nd at a distance of 500 to 900 km from its centre, is not justified. The causes responsible for absence of inversion generally at 850 mb over the Bay have been discussed. The conditions over the Arabian Sea 200-300 miles west of Western Ghats and over the Bay during the monsoon season are such that models for one cannot be made  applicable for the other, just as the subtropical cyclone model for the Pacific cannot be valid for the Bay when there is no inversion at 850-mb level.