Relationship between positive cloud-to-ground flash and tilted charge structure of thunderstorm

The relationship between the occurrence of +CG lightning and the tilted triple charge structure of thunderstorm is researched by establishing various three-dimensional models of triple charge structure of thunderstorm with a stochastic lightning discharge parameterization scheme. The results show that the horizontal movement of the upper positive charge region can't make the flash type convert from cloud lightning to +CG lightning, but will make the lightning more difficult to occur. When the middle negative charge region is moved in horizontal direction, it will result in more lightning discharges. Meanwhile the potential difference between initial point and ground reduced gradually. Due to this, although the downward propagation of the positive leader will not be blocked by the lower positive charge region, the reduction of the potential difference between the initial point and ground makes the positive leader more difficult to propagate to the ground. In the triple charge structures, when the charge density and scope of upper positive charge region are very large, the positive leader is possible to propagate to ground, driven by local charge and potential imbalance. But the tilt of charge structure will not make the thundercloud inclined to produce +CG.