Lightning channel reconstruction from thunder measurements

Abstract

The geometry of lightning channels can be reconstructed from thunder data obtained with an array of microphones. In this acoustic technique we divide a thunder record into a series of short contiguous time periods and, by using cross-correlation analysis, determine the direction of propagation of the predominant acoustic signal received during each of the time periods. If the atmospheric temperature and wind profiles are known, we can accurately trace the acoustic signals to their points of origin. The set of points generated in this manner from the complete thunder record delineate the geometry of the lightning channel. In application the accuracy of the channel reconstruction is limited by incomplete wind and temperature data; an example is given that reconstructs a lightning channel with an estimated error in the channel position of ≈10%. This technique is of particular value in investigating the nature of lightning channels inside clouds and in mapping the source regions supplying charge for lightning.