甘肃河东一次区域性冰雹天气的诊断分析

从大气环流背景方面,对2007年7月24～26日甘肃河东出现的一次区域性冰雹天气过程进行了分析,并利用NCEP再分析资料对物理量场进行初步分析。结果表明,形成这次连续性降雹的影响系统是稳定少动的蒙古冷涡;深厚的不稳定层结和随高度增强的不稳定能量是此次强对流发生的热力条件;有利的低层辐合与高层辐散的散度场是此次强对流发生的动力因子;副高外围的偏南气流向低涡东南部源源不断地输送暖湿空气,为冰雹的形成提供了水汽条件;合适的冻结层高度、厚度也为降雹创造了条件。

Diagnostic Analysis of a Regional Hail Weather Occurred in Hedong of Gansu Province

The circulation background of a regional hail weather which occurred on July 24-26,2007 in the eastern part of Gansu Province was discussed,the NCEP reanalysis data was used to preliminarily analyze its physical fields.According to the analysis results,the continual hail process was mainly caused by the stationary and stable Mongolia cold vortex;the deep unstable layer and unstable energy increased with altitude,providing the thermal conditions for occurrence of strong convection;a deep convergence layer on the low level and severe divergence layer on the upper level were the dynamic factors of the strong convection,the airflow from south edge of subtropical high made an abundant water vapor supply for hail formation;the height and thickness of freezing layer were very appropriate for the hail generation.