The North Indian Ocean basin which consists of Bay of Bengal and Arabian Sea witnesses mainly two tropical cyclone seasons: pre-monsoon and post-monsoon. My question is that what is it that causes the formation of tropical cyclones in this basin in post-monsoon season especially in the months of November and December. At that time of the year, sun's apparent position is near the Tropic of Capricorn in the southern hemisphere. Also the cyclones formed in this season are more destructive. What could be the reason behind this?