Lightning return stroke model with height‐variable discharge time constant

Abstract

A new lightning return stroke model is proposed in which the lightning channel, previously charged by the leader, is exponentially discharged with the discharge time constant being a general function of height. The new model is both more general and more physically reasonable than the Diendorfer‐Uman model (Diendorfer and Uman, 1990) and its modification by Thottappillil et al. (1991). In the new model a single height‐variable discharge time constant is used instead of the two height‐invariant discharge time constants used for natural lightning in the Diendorfer‐Uman model. As an illustration of the use of the new model, the measured electric fields for three triggered lightning return strokes about 5‐km distant are compared with the fields calculated from the model, using simultaneously measured channel base current and return stroke speed as inputs to the model.