Abstract
In the paper the author studied the position of development of 413 depressions/cyclones in the Bay of Bengal and 53 depressions/cyclones in the Arabian Sea, formed during 1924 to 1952. He found that the 200 mb level warm pool formed in the mean charts is connected with the cyclogenesis in the Bay of Bengal and Arabian Sea. Eight depressions of 1964, seven in the Bay and one in the Arabian Sea, were also found to have warm pools at the 200 mb level one or two days before cyclogenesis took place over the sea. He further studied one depression in detail and found the formation of a warm pool at the 200 mb level three to four days before the development of the depression below at sea level. The 200 mb level warm pool that forms generally three to four days earlier was attributed to be one of the causes of cyclogenesis of tropical storms/depressions.