Radar Climatic Characteristics of Severe Convective Cloud in Yongdeng, Gansu

Using the 19-year radar echo data in disaster area of Yongdeng, Gansu, the relation between the forming of severe convective echo and distributing characteristics with special topography characteristics of Yongdeng, Gansu, the large-scale weather background and its corresponding to severe convective echo moving, height, intensity and echo spectrum are analyzed. The results show that 1the special topography cause the air flow blocking and make it to turn back and converge, then vertical motion violently quicken, and making the convective cloud developed very quickly, which is the critical factor of the forming and distribution of convective cloud. 2the weather pattern at high level and the convective cloud construction restrict radar echo moving and echo basic characteristic. 3the echo spectrum of hail cloud show that convective activity of hail storm is exuberant state in general, the severe echo height and its temperature are important conditions for the formation of hail cloud. 4the change of hail storm echo intensity depends on the case intensity of hail storm.