Calculations of Electric Fields from Lightning above Finitely Conducting Ground

Abstract

Expressions for the horizontal and the vertical electric field components due to an arbitrarily oriented lightning channel above a finitely conducting ground have been obtained. The theory has been applied to the vertical return stroke and the horizontal lightning. It has been found that the shapes of the vertical and horizontal electric fields versus frequency curves remain the same at all heights above the ground. The frequency spectrum of electric fields from horizontal lightning is, however, different from that of a return stroke. The ratio of horizontal to vertical electric field above ground is less than 1.0 for a return stroke, while it is greater than 1.0 for horizontal lightning for all ground conductivities (except <img src='http://www.niscair.res.in/jinfo/sigma1.gif' border=0> = ∞).