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Re: Thunder
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To: tesla-at-grendel.objinc-dot-com
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Subject: Re: Thunder
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From: "SROYS" <SROYS-at-radiology.ab.umd.edu>
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Date: Thu, 25 Jan 1996 09:42:28 EDT
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>Received: from comm1.ab.umd.edu (comm1.ab.umd.edu [134.192.1.5]) by uucp-1.csn-dot-net (8.6.12/8.6.12) with ESMTP id HAA06123 for <tesla-at-grendel.objinc-dot-com>; Thu, 25 Jan 1996 07:45:37 -0700
> My gut feeling is that when a discharge causes depletion of a gas
> and the surrounding media collapses with sufficient velocity to cause
> a series of pressure variations -- it's the same as lightning and
> thunder.
Rather than causing a depletion and a collapse, the lightning
discharge superheats the air to the point where it expands faster than
the speed of sound, causing the shock wave we know as thunder. The
familiar "rumbling" sound is partially caused by the long (many km),
convoluted path that the discharge takes and the resulting delays in the
arrival of the sound from the different parts of the channel.
For more information on all aspects of lightning research, the book
"Lightning" by Martin Uman is available from Dover paperbacks for
under $10 and gives a detailed account of "modern" lightning research.
Steven Roys (sroys-at-radiology.ab.umd.edu)