Numerical Simulation of the effect of charge structure on the characteristics of discharge in thunderstorm 1

The Bi- directional Stochastic Lightning Parameterization scheme of parameterization of discharge was introduced in a three-dimensional dynamic-electrification coupled model. The effects of the structure charge, the positive charge , negative charge and the change of space potential on discharge were investigated by the simulation process of a thunderstorm. The results indicate that the initial position of lightning modulated by the variation about the concentration center of positive and negative charge could affect the characteristic of discharge, and lightning was triggered between the upper of negative charge and the middle of positive charge as well as between the bottom of negative charge and the middle positive charge, however, the direction of positive leaders is upward and the negative leaders is downward in the former, and contrary to the latter .In the prime or mid-term development of thunderstorm., because of the strong convection and cloud height, the types of lightning in cloud are mostly the reverse polarity in cloud. With the further development of convection, the bottom of electrical area was increased constantly, and as the cloud particles begin to build , most of grauple particles descend gradually to low level in the