Environment and Structure of Hail-Cloud at the end of North China Trough in Late Summer
Effected by the hail-cloud at the end of North China though,the central and southern regions of Hebei Province occurred a sudden severe storm on 27 August 2009,and the diameter of hail exceeds 40 mm,which led to serious disaster.The event was rare in the same period of history.Based on conventional observational data,Doppler radar and satellite detection information and retrieval products,Automatic station data,NCEP reanalysis data,the environment and structure of storm were analyzed.The result showed that the southward weak cold air triggered the severe convection and the boundary on the surface promoted the development of mesoscale convective systems.The hail cloud developed in the environment of up dry and low wet air levels.The latent heat of condensation might provide the energy for the rapid development of hail cloud and the moderate deep layer vertical wind shear might provide the dynamic conditions.However,the thinner and lower moist air level,relatively high 0 ℃ layer(higher than the average height in history) at 08:00,higher TBB made it more difficult to forecast the severe convection.However,the relatively higher cloud optical thickness might give the forecast information before the severe convection developing.The hail cloud was of the supercell-cluster characterized of linear arrangement in radar reflectivity and right propagating of multi-cells made the strong storm to be sustaining.
NETL
NSTL
万方数据
维普
