一次西风槽系统的云微物理结构分析

对１９９１年４月１６日影响河北地区中南部的一次西槽天气过程形成的降水性层状云微物理结构进行了分析。结果表明，降水主要发生在层状云的中上层，存在可供催化的过冷层和过冷水，但云体下层的供水云较薄，云底偏高，不利于降水的发展；实施人工增雨作业后，云层微结构出现相应变化（云滴和雨滴含水量增加，滴谱拓宽等）作业区与影响区雨量普遍增加，并与催化时间相吻合，这些可能与人工影响有关。

An Analysis of the Microphysical Structure of Clouds in the Westerly Trough System

The micro-physical structure of precipitable stratiform clouds are analysed in the westerly trough system over the central and south parts of Hebei Province on April 16, 1991. The results indicate that the development of precipitation was carried out mainly in the stratiform clouds in the middle and upper levels. Although there are favorable conditions for ice crystal growth i. e. the catalyzables of supercooled area and water. The development of precipitation is disadvantageous due to the thin water supply clouds and the high cloud base. After the aircraft seeding operation,the micro-structure of the clouds has been varied (the water content of cloud droplets and rain droplets increased obviously. There is an evident expanding in the droplets spectrum. etc. ), the precipitation capacity increased in the area of seeding operation and influenced area within the effective period of artificial catalysis. These results are in agreement with the clouds modification.