中尺度暴雨云团发生发展前的一些征兆

利用湿有效能量方法找出了盛夏午后北京地区中尺度暴雨云团发生发展的一些征兆：（１）北京地区已贮存着大量能量；（２）湿有效能量正在北京地区积聚；（３）低层流场结构有利于出现强迫抬升；（４）北京地区与河套地区之间午后将出现非绝热加热形成的巨大水平温差。

A Few Signs of Occurrence and Development of Meso-scale Cloud Cluster Accompanied by Heavy Rainfall

A few signs of occurrence and development of rneso-scale cloud cluster accompanied by heavy rainfall during midsummer afternoon over Beijing area had been found by the use of the moist available energy method. They are as follows :a) a lot of moist available energy was already stored up over Beijing area;b) the moist available energy is being accumulated over Beijing area; c) the flow pattern in the lower troposphere is favourable for the occurrence of the forced lifting;d) there will be a larger temperature contrast,which results from diabatic heating process,in the area between Beijing area and the bend of the Yellow River in the afternoon.