Abstract:
Acoustic signatures of thunder can be used in
understanding some properties of lightning channels. Basic
features of thunder signal are qualitatively classified as Peals,
Claps and Rumble. In studies [1] and [4], attempts have been
made to recognize these features quantitatively. To strengthen
previous findings, above features were analyzed using Stransformation in this study. Characteristics of Peals, Claps and
Rumble are directly affected by the acoustic energy, channel
tortuosity, the interference of distinct parts of the channel,
channel orientation relative to the observer and attenuation of
high frequencies during the propagation. The fundamental
frequency of audible thunder appears less than 250 Hz. Stransformation was introduced to estimate the fundamental
frequencies and mean frequencies of thunder features with a
level of significance. The elapsed time of peals and claps depends
with the intensity level and the frequency composition of the
fluctuation. The mean fundamental frequency of rumbles is 63
Hz.
