SOME SYNOPTIC ASPECTS OF COLD VORTEXES OF TROPICAL UPPER TROPOSPHERE OVER NORTHWEST PACIFIC IN SUMMER

The frequencies and cloud patterns of cold vortexes of tropical upper tropos-phere are studied. Near the center of typical cold vortex, there is a cloud less area with a surrounding cloud band. The inner cloud less area is dry and cool with subsiding motion in troposphere and the outer cloud band is wet with ascending motion extending from lower troposphere to 300-400 mb. The cold vortex may provide a favourable environment for initial development of typhoon. The outer cloud band provides a high-θse air path through middle troposphere, while the inner cloud-free area has compensative subsiding motion.