Phase Of Heavy Rain / Snow Cloud Hydrometeors And Thermal Kinetics Of The Process Of Interaction

In this paper, four cases of heavy rainfalls and snowfalls in China are simulated by using MM5. Cloud microphysical characteristics and sources of rain, snow and graupel have been particularly studied. At the same time, the effects of dragging force from fall of hydrometeors and latent-heat release from phase transfer are tested.From the analyses we conclude that the distributing of the cloud particles relates with temperature closely. Huanan heavy rainfall and mei-yu front heavy rainfall have mixed-phase process with vapor phase, liquid phase and ice phase. Rain water is produced mainly by three processes: melting of graupel, collection of cloud water by rain, and conversion of cloud water into rain. Cloud water is the most important source of graupel. For snow, collection of ice by snow, collection of rain by ice and depositional growth of snow are the main sources. The effect of dragging force weakens the convection and the effect of latent-heat release strengthens the instability. Both of them are evidently feedback actions to the environment.In the case of Beijing snowfall, the temperature is below 0℃. There are only vapor, ice and snow in the cloud. The hydrometeors and its sources are smaller than those of heavy rainfalls. And the feedback actions of the dragging force and the latent-heat release are not evident.Liaoning snowfall is a process of rain followed by snow. Both liquid phase and ice phase are abundant so that it has mixed-phase characteristic. The sorts of hydrometeors and their sources are similar to those of heavy rainfalls. The effect of dragging force also weakens the convection and the effect of latent-heat release strengthens the instability.