A Method to Include the Effects of Tortuosity in the Electromagnetic Field Expressions produced by Vertical Lightning Channels

The electromagnetic fields (EMFs) produced by a lightning discharge are usually computed by supposing a vertical channel. However, the tortuous path of channels represents a realistic feature of lightning strikes and can drastically modify the radiated EMFs. Numerical methods for their computation have been developed, mainly based on the superposition law as applied to consecutive rectilinear segments, properly oriented in order to create a tortuous path; however, such methods require a high computational effort, which may be unfeasible for realistic problems. As an alternative approach, this work introduces an equivalent tortuous function, which aims at taking into account the channel tortuosity in the EMF expressions produced by a vertical channel. The proposed function is obtained as the regularized solution of an appropriate inverse problem, and is validated against several tortuous lightning channels.