CONDITIONS ASSOCIATED WITH FREEZING PRECIPITATION AT AIRPORTS OF RUSSIA AND THE CIS. 1. AIRPORTS OF THE MOSCOW AIR ZONE

摘要

Surface hourly observations, radiosonde, and objective analysis data are used to study meteorological conditions of freezing rain and freezing drizzle in the Moscow airports. The cloud top heights are derived from the radiosonde data. It is found that in about 25% of cases of freezing precipitation (mainly, rain), the temperature profiles are characterized by layers of positive temperature within the clouds. In more than half of the cases, negative temperatures are observed in the whole troposphere. In these cases, freezing drizzle dominates. The freezing precipitation occurs mainly in the surface pressure cyclonic fields, in frontal zones, and under warm ad.vection. All the relationships with surface weather, vertical structure of the atmosphere, and synoptic features are more pronounced for freezing rain than for freezing drizzle.