Cumulonimbus cloud with anvil over India : Synoptic cloud type observations 1970-2000

Abstract

The features of observational aspects of frequencies of occurrence of Cb clouds with anvil over India have been presented. Synoptic cloud type observations for 101 uniformly distributed Class I surface observatories of India Meteorological Department for pre-monsoon months for period 1970-2000 is taken.

The results reveal that the formation of Cb clouds with anvil exhibit the diurnal tendency of growth of cloud areas and show drastic decrease in the early morning hours. The temporal evolution of Cb clouds with anvil show that during the period from 0900 UTC to 2100 UTC, the maximum peak of convective cloud activity occur at 1200 UTC. This study has brought forth five prominent belts of Cb clouds prevalence showing both temporal and spatial characteristics during the month of May which is the month of peak thunderstorm activity. The first belt extends from South peninsula along West Coast of India covering regions of Kerala, Tamil Nadu and Puducherry, South Interior Karnataka, Coastal Karnataka, parts of North Interior Karnataka, Konkan and Goa, Madhya Maharashtra and West Madhya Pradesh (3 to 10 days). The region South Interior Karnataka and adjoining Kerala and Tamil Nadu has reported Cb clouds with anvil to be about 10 days. The second belt comprises Himachal Pradesh and adjoining Jammu & Kashmir, Uttarakhand and adjoining West UP. The third belt covers spatial areas of Chhattisgarh and adjoining Vidharbha, Orissa, Gangetic West Bengal and adjoining areas of Jharkhand and Bihar. The fourth belt is SHWB, Assam and Meghalaya covering Guwahati and Shillong. The fifth belt comprises regions of Tripura and adjoining Mizoram. The rest of Northeast India report Cb clouds with anvil on the average of 1 to 3 days. The region South Bihar and adjoining Jharkhand and Gangetic West Bengal report Cb clouds with anvil on the average of 5 to 7 days.