Modeling of the Stepped Leader Initiation Process in an Altitude Triggered Lightning

In an altitude triggered lightning, the potential and charge distribution of the triggering wire, a floating conductor, is unknown and changeable during the triggering process, which makes it difficult to simulate an altitude triggered lightning in a numerical work. To solve this problem, a 3D altitude triggered lightning model is developed in this paper, which contains two parts, a Thundercloud Model which is time-dependent and nonhydrostatic and takes 27 kinds of microphysical processes into consideration and a Triggering Model in which a charge conservation equation is introduced to describe the floating conductor and to ensure the overall neutrality of the leader channel. Numerical results of the stepped leader initiation process are given, which are in good agreement with experiment observations.