Lightning current observation of an altitude-triggered flash

Abstract

In this work we present some current parameters of an altitude-triggered lightning using a 30-m insulating cable of Kevlar. It was triggered during the summer of 2001–2002 at International Center for Triggered and Natural Lightning Studies (CIPRIN) in Brazil. The flash connected to the tip of a Franklin rod equipped with three different current sensors. Measurements of current intensity, done at sample rate of 100 ns, enabled the study of some characteristics of seven return stroke waveforms. The geometric mean peak current of the altitude flash strokes was 2 to 3 times higher than the values usually reported for classical strokes. Except for the 2 first strokes, which exhibited chopped waveforms, the charge destroyed in each stroke was similar to the geometric mean values usually reported for classical strokes. Most of the other waveform parameters showed significant differences from the usual values presented in the literature for classical triggered flashes. The values presented here are unique and will add information to the very few current data published on altitude-triggered lightning in literature.