PARAMETERIZATION OF PHYSICAL PROCESSES FOR HAILSTONE GROWTH

The theoretical and experimental researches on the process of hail growth have expressed that the mass and heat transfer of hails surface decided the rate of hails grow th and structure,the hails dynamic character de cided it smovement,time of stopping in cloud and the disaster degree after the hail landed on ground,in a word,decided the hail sgrowth.The hails mass and heat transfer affect sgrowth,melting and evaporation of hail.Butmany researchers used the transfer coefficient which Ranz and Marshall measured on water drop evaporation under small Renold number (Re≤200) and expanded it to 104×Re≤107 (the actual hails mass and heat trans fer coefficient),it exists bigger difference.Zheng (1994) measured accurately the surface temperature of coolingice particle using AGMA system under the range of 1.1×104Re≤5.2 104 and developed the numerical model to compute the Nusset number.On the basis of the experiment mentioned above,the paper paramet erized the experiment result in the range of Renold numbers corresponding to natural hails Renumber,then putit in 1D and 3D cumulus model to compute the hails growth situation of 4 different areas of China under various pa rameterization schemes.we found that the hail growth,melting and evaporation difference from that of Provo scheme.The hail melting rate is 12% 50% bigger than the previous model and the hails evaporation rate is 10% 200% bigger than the previous model,the dry and wetgrow thrate is 10% 40% bigger than the previ ous model.