Characteristics of Triggered Lightning Observed in Brazil

Several parameters of return-stroke current waveforms of triggered lightning are discussed and compared to results obtained in other places. The parameters presented in this paper, obtained for the first time in Brazil, are crucial in the lightning protection research. All these measurements were done with a sample rate of 100 ns, enabling us to study rise and decay times of the waveforms. Images from a high-speed camera were also used in this work. The triggered lightning, artificially initiated by the “classical” and the “altitude” techniques, were performed during the summer of 2001 and 2002 at International Center for Triggered and Natural Lightning in Brazil (Cachoeira Paulista, S 22°41.2; W 44°59.0; altitude: 625 m). Most triggered lightning strokes in this study have uncommonly higher peak current intensities. These high peak current values were confirmed by the registered magnetic field in the magnetic cards. Also the average duration of the strokes were shorter than usually reported in literature. Measurements of current and light intensity are also compared in order to find a relationship between them.