液态水含量和冰晶浓度对闪电频数影响的数值模拟研究

Numerical Simulation of the Effect of Liquid Water Content and Ice Crystal Concentration on Lightning Flash Frequency

假定在软雹和冰晶碰撞的非感应起电机制为主要的起电机制成立的条件下,数值模拟研究了国际上公认的Fletcher和H-M冰晶产生机制以及云中的液态水含量对雷暴云放电过程(区分了云闪和地闪)的影响。结果表明,随着气压和温度的变化,在两种冰晶产生机制假定下,冰晶浓度分布有很大差异,这直接导致了雷暴云内电活动的差异。液态水含量的增加将使得首次放电时间延迟,同时将引起放电位置的下降和闪电频数的减少。

Assuming that collision between ice crystals and rimed graupel particles is the dominant mechanism for charge separation in thunderstorms, a numerical simulation has been used to study the effect of two ice glaciation mechanisms of crystal （Fletcher and Hallett-Mossop glaciation mechanism）and liquid water content on flash rate. The results show that there is a big disparity on ice crystal number concentration distribution with increasing of the pressure and the temperature in two glaciation mechanisms,this directly result in a difference of electrical activity of thundercloud. With liquid water content increasing, the time of the first lightning flash will be delayed, the location of breakdown process will be descended, and the lightning flash rate will be decreased.