LIGHTNING RETURN STROKE ELECTRIC-FIELDS ABOVE GROUND

The vertical and horizontal field wave shapes derived from the Lienard-Wiechert potentials for a lightning return stroke are presented. The calculations were performed for ranges from 50 m to 5 km and altitudes from ground level up to 10 km, assuming a finitely conducting ground. It was found that the finite ground conductivity affects the fields at close ranges and lower altitudes. It was also found that the effect introduced by considering the Lienard-Wiechert potentials is to increase the initial field peaks and the time to peak. The maximum deviation in peak fields observed due to this effect is 40%.