The Physical Images and Mechanisms of Severe Rain in Hubei Provice

The geostationary satellite images and synoptic maps of 14 cases of excessive heavy rain occurred in Hubei Province from 1981 to 2003 were analyzed carefully.Not only water vapor but also liquid water transfer had been found in these cases.It was found that the triggering precipitation cloud systems of excessive heavy rain were quasi-zonal baroclinic leaf cloud system and mesoscale vortex cloud system.Ambient cloud fields characteristics of satellite cloud image and four image types of excessive heavy rain were deduced.The mechanism of excessive heavy rain was that the excessive heavy rain was triggered by mesoscale eddy or upper level jet stream moving eastward and covering the "dew point front" and warm moisture air mass.The "CISK" was the main mechanism.The "dew point front" played a key role in triggering and keeping the excessive heavy rain.