Unusually long duration lightning electric field return strokes in Malaysia

This paper presents the characteristics of lightning generated vertical electric field waveforms recorded in Malaysia. The focus of the study was the waveforms with unusually long zero crossing times. A total of 207 lightning ground flash records were analyzed out of which nine flashes contained the return stokes that have long durations of zero crossing. In contrast to the majority of return strokes that have zero crossing times in the order of 40-70 μs, these unusual return stroke waveforms are characterized by zero crossing times between 0.66 ms to 7.96 ms.