庆阳市一次局地冰雹天气分析

利用常规气象资料和多普勒雷达资料，从天气形势、物理量场和雷达回波演变特征3方面分析了2006年8月2日庆阳市局地强降雹的天气过程。结果表明：此次降雹过程在500hPa高空环流形势场上呈典型的西北气流型，低层辐合、高层辐散，对流层中层正涡度区的耦合激发低层上升运动加强，有利于本地水汽向上输送；河套北部短波槽促使冷空气动力下传是这次局地强对流天气最主要的动力触发机制；从雷达回波的演变来看此次降雹并非是典型的冰雹云回波特征，而是由飑线造成的对流云相互碰并增强后产生的冰雹；同时卫星云图上云顶亮温的变化与对流云团的发展也有着很好的对应关系，单个云团的合并有利于能量的集中和加强，易于产生冰雹。

Analysis of a Local Hail Process in Qingyang of Gansu Province

Based on the routine meteorological data and the Doppler radar date, the causes of a hail process occurred on August 2, 2006 in Qingyang were analyzed from the synoptic environment, physical quantity field and the characteristics of Doppler radar echoes. Results show that it was a typical northwest flow pattern at the level of 500 hPa, the lower air convergence and the upper air divergence, the coupling of the positive vortex in the middle troposphere led to the lifting movement developing in the low level, and this was advantageous to the upward transportation of the local water vapor; the short wave trough at the north of Hetao area caused the cold air to move down and this became the main triggering mechanism of this process. The Doppler radar data analysis showed that the process occurred after a strong convection cloud which created by a squall line, and there was a good corresponding relationship between the change of the cloud top temperature and the development of the convection cloud; the merge of the single cloud cluster was advantageous to the energy enhancement and easy to produce the hail.