A model for negative first return strokes in lightning flashes

A model is introduced to describe negative first return strokes in lightning ground flashes. The basic assumptions made are similar to those used previously to describe the subsequent return strokes. The model predictions are in general agreement with experimental observation. The model predicts the relationships between (a) peak current and the peak electric radiation field and (b) the peak derivatives of current and electric radiation field. These relationships can be used in the remote sensing of first return stroke current parameters through the measured radiation fields.