兰州冰雹特征的统计分析

统计表明,兰州冰雹是小概率事件,年降雹次数有减少趋势,季节变化为6、9月双峰型,主要降雹时间集中在午后.雹云入侵路径有准定常性,可分为北、中、西、南4路,雹云移动路径是连续的,但冰雹落区不连续.境内永登西北部是冰雹高发区,红古西部、皋兰北部、榆中北部、市区、榆中南部山区等地是冰雹多发区.

Analysis of hail characteristics in Lanzhou

The statistics shows that the hail in Lanzhou is an event with small probability.The hail has the tendency to decrease annually and the climax seasons are June and September.The hail always happens in the afternoons and its route has the principle to follow.It comes from northern,central,western and southern directions.The hail motion is consecutive and it drops unevenly in different places.The north-western part of Yongdeng is the area where hail occurs most frequently.In other areas such as the western part of Honggu,northern part of Gaolan,the north mountain of Yuzhong,the urban area and southern mountain areas in Yuzhong the hail occurs on occasions.