Experimental Determination of Lightning Propagation Velocity at Low Altitude

摘要

The average velocity of propagation for positive upward streamer and downward leader was determined using switching time of Mzrx's impulse generator. The average flashover current was 6KA and a high voltage Marx's impulse generator rating was 1.25 megavolts, 3.5 kilojoules. The tests were performed under thunderstorm atmospheric conditions: high absolute humidity 12.5 +- 5 g/m~3 and electric bias (ground positive) 20 KV/M. Also an empirical formula was developed for an average velocity of lightning propagation as a function of lightning intensity similar to the Whitehead's relationship for the last fractal (jump) D=101~(65) meters, I in KA (kiloamps) (1). The determined relationship (formula) for lightning propagation velocity at low altitude is V=678x10~6I~(364) meters per second, I in KA (kiloamps). All the tests were performed at Inchcape (ETL) Testing Laboratories, Inc., Cortland, N.Y.13045.