Computed Lightning Electric Field Ratios of First and Subsequent Return Strokes

Electromagnetic fi elds generated due to ‘typical’ fi rst return stroke (FS) and subsequent lightning return stroke (SS) have been computed and compared. The simulation results are discussed keeping in view the fi eld data reported in several recent literature, which compares the severity of fi rst and subsequent return strokes. The MTLE based engineering model is adopted to compare the severity of lightning return strokes (FS/SS) as a function of radial distance and the worst case ground conductivity.

In general, the magnitude of electric field peak due to of first return stroke is nearly twice that of field peak due to subsequent return stroke as reported in the literature, based on the data collected by lightning detection, information and field measurement systems. The present simulation results not only substantiate this fact but also try and assess few parameters responsible for low ratio of FS/SS (reported in some cases) through simulation process; as causes for these low ratios are yet to find satisfactory explanation.