In order to study scientificity of artificial hail suppression and evaluate objective effect of hail suppression and reduce disaster of hail, using the comparative method in the physical validity checking theory, the evolution of 711\|type radar echo of two hail clouds before and after hail suppressions on July 24, 2007 have been analyzed. The results show that, after the one times hail suppression, the maximum echo intensity of A hailcloud is decreased 10 dBz and the 45 dBz echo top height is lowered 0.8 km and its width is increased and echo intensity is weakened and echo is expanded and split and stopped moving and combined behind clouds the reverse merger on PPI. After the four times hail suppression, the echo top height of B hailcloud is lowered 1.3～0.4 km (average 0.85 km) and the 45 dBz echo top height is lowered 0.9～0.4 km (average 0.65 km) and echo is split two parts and expanded after the previous two operations and echo area continues to increase and split after the last two operations. Therefore, the artificial hail suppression to two hail clouds is effective.Key words: Hail suppression effect; Radar echo; Hail cloud
