Contrast Analysis of Two Squall Lines under Different Vertical Wind Shear Conditions

Based on the conventional surface and upper observation data,densified observation of precipitation data,sounding data and NCEP reanalysis data,the two squall lines which occurred on the July 19,2010 and July 26,2011 were analyzed.The results are as follows.The same characteristics are: The two squall lines both occurred ahead of the 500 hPa trough,and accompanied by high speed winds and short-duration heavy rain,The wet layers were both deep,DCAPE were large in the two processes.The differences are that the squall lines occurred on July 19,2010 had obviously vertical wind shear,and CAPE was relatively low.The squall lines occurred on July 26,2011 had small vertical wind shear.The convective unstable energy was very large.Besides the high speed wind and short-duration heavy rain,the squall line produced the hail as well.