High-speed camera observations of negative ground flashes on a millisecond-scale

A study of cloud-to-ground lightning characteristics based on high-speed camera observations of 455 flashes related to 40 thunderstorms is presented. The Brazilian Lightning Location Network (RINDAT) was used to calculate the polarity and the distance of the flashes to the camera. In some cases, a fast electric field flat antenna was also used to calculate the time difference between strokes on a microsecond-scale. Some general features of the data set are briefly presented. This paper is focused on two specific characteristics observed in video records with a frame a rate of 1,000 frames/s: (i) six strokes presenting two ground terminations that were simultaneously connected for some milliseconds, (ii) and a high number of continuing current occurrences with durations less than 10 ms.