Simulating electrodeless discharge from a hydrometeor array

The objective of this research was to test, by means of an experiment in a high-voltage laboratory, the effect of an array of hydrometeors on the processes involved in the streamer-leader formation of lightning. Because the common types of hydrometeors present whenever lightning initiation in thunderstorms occurs are ice particles (graupel, hail, or ice crystals), we used, in this experiment, conductive particles similar to hail in size, with various spacing between them, but all under normal atmospheric pressure and room temperature. The laboratory array was suspended on dielectric threads in a uniform electric field of 1 MV m(-1) in the middle of the gap between the high-voltage and ground electrodes. During the first phase of the experiment, we studied the formation of a bidirectional arc discharge from the array and the effects of the array's size on the electrical characteristics and on the speed of development of the discharge. We continued with the same objectives in the second phase of the experiment, adding high-speed video observations with a recording speed of 10 Mfps, to observe all stages of the streamer-leader formation.