Abstract
Precipitation processes and the structure of precipitating clouds in cold polar continental air mass transformed over the warm sea surface were studied on the basis of radar observations and ice nuclei measurements made around the Southwest Islands, specially over the South Okinawa region, during AMTEX periods in 1974 and 1975. It is concluded that only lower cumulus clouds were not able to produce the rainfall detected on the ground in the situation of cold air outbreak, except in relation to synoptic disturbances such as East China Sea cyclone and fronts. The rainfall which was observed with the amount more than 0.5mm per 6 hours over the South Okinawa region in the situation of cold air outbreak resulted from the coupling of lower cumulus clouds and middle-level clouds which are inferred to have been formed in association with water vapor and ice nuclei transported from the South China Continent by westerly wind.
