Study on the Reason of Freezing Rain and Snow ...

Freezing rain is a weather phenomenon in early winter or end of winter/ beginning of spring. When strong cold air southward confronts with a warm and moist air, cold air inserts below the warm air, and near-surface air temperatures declines abruptly to below 0 ° C (but not too low), warm and moist air is upraised and give rise to rain or snow. In mid-January to early February 2008, large-scale of middle and lower reaches of Yangtze River and South China region experienced a process of continuous rain and snow. In this paper, after analyzing physical fields of the second process, there are several reasons for the formation of freezing rain disaster are found: (1) The basic condition for freezing rain occurrence: provision of water vapor. (2) An important condition for freezing rain occurrence: the strong upward motion. (3) The favorable conditions for freezing rain occurrence: the conditions of the existence of temperature inversion, and warm with the nose and is conducive to the emergence of freezing rain. (4) The supplement condition for freezing rain occurrence: moisture atmosphere frontogenesis. Because of cloud physics, micro- meteorology and many other effects of the distribution of freezing rain with some areas of local nature, and therefore, accurate prediction of its need for more research.