Abstract
Interferometric observations of cloud-to-ground flash in Darwin have been analyzed to investigate some features of the lightning. Our study focuses a comparison between multipoint and multiple negative cloud-to-ground flashes. We estimate the speed of leaders with submillisecond resolution for both multipoint and multiple strokes. The leader that precedes first stroke for mutiple flash progresses in a stepped fashion, and its behavior seems to be similar to that for multipoint flash. The speed of the leader is estimated at the mean value to 105m/s order, and the mean step length is found to be 96 meter with a mean pause time of 73 microsecond. The running time of the leader analyzed here takes the mean value of 89 microsecond. The duration of UHF radiation of leader which traces the former channel ranges from 0.2 to 55.3 millisecond with a mean of 7.5 millisecond. To the contrary, those preceding multipoint strokes ranges 21.1 to 90.6 millisecond with a mean value of 47.5 millisecond. The time interval between strokes which strike the same point as the former stroke ranges from 22.5 to 330.6 millisecond with a mean of 75.1 millisecond, and those for multipoint strokes ranges from 55.6 to 633.7 millisecond with a mean of 149.1 millisecond. All of the leaders preceding multipoint strokes starts at the same region inside the cloud.
