DROP EFFECTIVE RADIUS IN MAIN CLOUD TYPES AND FRONTAL CLOUD SYSTEMS ESTIMATED BY SATELLITE OBSERVATIONS IN WARM PERIOD OF YEAR

Abstract

The distribution of drop effective radius on cloud upper level was defined and analyzed for main cloud forms over Ukraine during two years (2014-2015) using satellite observations. The effective radius values of isolated cumulonimbus on cloud top and its dependency on optical thickness was estimated in measurements during April-September 2014 over Kyiv area. For cumulonimbus clouds with precipitation the dependence of effective radius on the type, precipitation intensity and liquid water path was defined. The distribution of drop effective radius on cloud top in the strength frontal systems with heavy showers area over all territory of Ukraine was defined for two systems and it dependence on the cloud height and the precipitation type, their intensity and the liquid water path was estimated. For all types of clouds the size of effective radius of the droplets was 6 μm. In St and As cloud system droplets with this size of effective radius were observed in 100%, in Sc and As cloud system – 91-92%. The values of effective radius in Ns and Cb cloud system was close to 6 μm (71 and 89% respectively). Larger droplets (8 μm) in Ns were observed in 29% and in Cb in 9%. However, in Cb, accompanied by rainfalls and powerful thunderstorms, the values of effective radius were 10-15 μm (1.5%) and 25-45 μm (0.5%). In 75% of moderate precipitation cases were formed by drops with an effective radius of 6 μm and in 25% with an effective radius of 8 μm. For the heavy precipitated clouds, the drops with an effective radius of 8 μm (62%) had the highest frequency, in 33% the effective radius of 6 μm were observed. The larger droplets (≥10 μm) had a small frequency (5%). The drop effective radius for cases of heavy rainfalls was 8 μm in 75%, in 25% larger droplets were observed (10, 15 and 30 μm). More intense rainfall was accompanied by greater values of cloud water content and, accordingly, greater effective radius values. The cases with large values of microphysical parameters and precipitation were observed as streaks in frontal cloud systems.