Mechanisms of precipitation initiation in convective clouds around Delhi - A radar study

A study has been made to assess the role of different rpesipitation mechanisms in clouds over Delhi region in north India. The study is based on radar observations of precipitation echoes from 13394 convective clouds within 100 km around Delhi collected during the 25-yr period from 1958 to 1982. Precipitation initiation mechanisms involved in convective clouds have been judged by the height of initial radar echo from clouds relative to the freezing level. The study has suggested that, on annual basis, in about 54 of convective clouds forming in Delhi region, precipitation initiation is due to purely collision-coalescence process. Seasonwise analysis showed that in winter, pre-monsoon, monsoon and post-monsoon periods the mechanism of precipitation initiation is due to collision-coalescence process in 28, 61, 57 and 43 of cloud cases, respectively, while in the remaining cloud cases in each season, no definite conclusion could be drawn regarding the precipitation formation mechanism involved in them