Audible thunder characteristic and the relation between peak frequency and lightning parameters |
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Authors: | OUYANG YUHUA YUAN PING |
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Institution: | 1.College of Physics and Electronic Engineering,Northwest Normal University,Lanzhou,China;2.School of Mathematics, Physics and Software Engineering,Lanzhou Jiaotong University,Lanzhou,China |
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Abstract: | In recent summers, some natural lightning optical spectra and audible thunder signals were observed. Twelve events on 15 August
2008 are selected as samples since some synchronizing information about them are obtained, such as lightning optical spectra,
surface E-field changes, etc. By using digital filter and Fourier transform, thunder frequency spectra in observation location
have been calculated. Then the two main propagation effects, finite amplitude propagation and attenuation by air, are calculated.
Upon that we take the test thunder frequency spectra and work backward to recalculate the original frequency spectra near
generation location. Thunder frequency spectra and the frequency distribution varying with distance are researched. According
to the theories on plasma, the channel temperature and electron density are further calculated by transition parameters of
lines in lightning optical spectra. Pressure and the average ionization degree of each discharge channel are obtained by using
Saha equations, charge conservation equations and particle conservation equations. Moreover, the relationship between the
peak frequency of each thunder and channel parameters of the lightning is studied. |
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Keywords: | |
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