We have performed a lightning observation campaign in Lhasa city, Tibet plateau region of China. It was found that the thunderstorms in Lhasa city exhibit positive dominant electric fields at the ground and tend to produce smaller ratio of cloud-to-ground (CG) discharges. Among the CG discharges recorded, nearly 90% of them are negative ones. Compared to those occurred in low land areas, these negative CG discharges exhibit similar characteristics in terms of the number in a flash and the

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... troke interval, but larger 10-to-90 %.fast-transition rise times for both the first and subsequent strokes.