A Case Study of Cold Air Activity during Meiyu Period in July of 1991
1991年梅雨期中冷空气活动的个例分析

The trajectories of cold air in heaVy rainfall Period of Jiang-Huai district July 4-6, 1991 show the cold air, which confront with the warm moist air in the Yangtze myer basin, came from the Northwest.The formation of 500 hpa trough on the set of Tibet Plateau, which cause the cyclone to develop in the Meiyu front, is related to the cold air activity.