Some field parameters of return strokes in upward lightning from tall objects

In this paper we show an analysis regarding the Peak-to-Zero (PTZ) time, the rise time, and the peak current for strokes to tall objects. It was previously shown that field pulses radiated by return strokes to the Gaisberg Tower (GBT) exhibit a smaller PTZ time than natural CG strokes [1]. We compare field data (LLS sensor reported field parameters) from strokes to the GBT to field data from strokes detected during winter thunderstorms. We show that winter thunderstorms exhibit smaller PTZ times independent if the strike is to a tall object or not. We also present evidence that the PTZ time does not depend on the lightning channel length, using the altitude of the -10° C isotherm as a proxy of the channel length. The -10° C isotherm is often assumed to be the altitude of the negative charge center. The results obtained in this study indicate that the hypothesis of an influence of the channel length on the resulting PTZ time is not valid.