Abstract:
Based on the conventional meteorological data, the National Centers for Environment Prediction Final Analysis (NCEP-FNL) data, new generation Doppler radar and the temperature of black body (TBB) data from Fengyun−2F (FY−2F) satellite, this paper compares and analyzes the environmental fields and physical quantity characteristics of two large hail weather processes in Pingtang County, Guizhou Province, where FAST is located, in the past 5 years. The results show that the cold trough in upper-level, the vortex shear in low level, and the strong jet in the middle and low levels were the common circulation characteristics of the two large hail processes; strong unstable stratification, abundant water vapor in the lower layer and certain lifting conditions were the same physical quantity characteristics of the two hailstorms. However, the triggering mechanisms of the two large hail processes were different: the "April 9
th" process was triggered by the convergence line on the ground, while the "March 4
th" process was an elevated thunderstorm triggered on the cold pad of the stationary front. The appropriate height of 0 ℃ and −20 ℃ layers is conducive to the growth of hailstones; meanwhile when the thickness of 0 ℃ layer and −20 ℃ layer is smaller and the vertical temperature gradient is larger, it is more conducive to the generation of large hailstones. The SWEAT and CAPE indexes have a good indication of hail value center of the index before the hail falls coincides with the high falling area, and the larger the index value, the larger the diameter of the hail. In addition, the strong vertical wind shear was also an important factor for those two hailstorms.