Accession Number : AD0253115

Title :   THE ACOUSTICS OF THUNDER

Corporate Author : HARVARD UNIV CAMBRIDGE MA ACOUSTICS RESEARCH LAB

Personal Author(s) : REMILLARD, WILFRED J.

Report Date : SEP 1960

Pagination or Media Count : 1

Abstract : A survey was made of the extensive literature on lightning and the meteorological conditions which exist during thunderstorms. Particular emphasis was placed on phenomena which might affect the generation, development, and propagation of thunder. It was then possible to formulate mathematical models of a lightning stroke and of the lower atmosphere, which are consistent with these phenomena and which account for many of the salient features of thunder. The long duration (or roll) of thunder, and the periods between the sudden, sharp, loud sounds (or claps) of thunder, which are predicted by these models, are shown to be in good agreement with observational data. Theoretical analysis predicts the existence of an invariant characteristic of the frequency spectra of thunder. A method was developed for obtaining such spectra when the time variation of the sound pressure is known. Then, a typical frequency spectra was deduced from the theoretical sound radiated by the model source, and the invariant characteristic (the product of the observation distance and the dominant frequency) was calculated. This value agrees well with the corresponding quantity taken from measurements of actual thunder. (Author)

Descriptors :   *ACOUSTICS, *CUMULONIMBUS CLOUDS, *LIGHTNING, FREQUENCY, MATHEMATICAL ANALYSIS, SOUND TRANSMISSION.

Distribution Statement : APPROVED FOR PUBLIC RELEASE