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Re: Thunder

As far as I know, thunder is not really caused by a collapse of gas dut 
to its depletion.  We all have discussed the resistance of air.  When you 
pass current throught a wire, it heats up due to joule heating.  Place 
more resistance, and the wire gets hotter.  The air around a Tesla coil 
or lightning bolt acts as the wire.  With all that voltage and current 
flowing thorugh the air, the result is and explosive expansion of the gas 
as it heats up.  This is what causes the repercusions of sound waves.

On Wed, 24 Jan 1996 tesla-at-grendel.objinc-dot-com wrote:

> >From tasa1.army.mil!darl-at-uucp-1.csn-dot-net Wed Jan 24 14:17 MST 1996
> >Received: from tasa1.army.mil (TASA1.ARMY.MIL [192.101.146.66]) by uucp-1.csn-dot-net (8.6.12/8.6.12) with ESMTP id OAA28346 for <grendel!grendel.objinc-dot-com!tesla-at-uucp-1.csn-dot-net>; Wed, 24 Jan 1996 14:08:27 -0700
> Date: Wed, 24 Jan 1996 13:07:14 -0800
> From: R Lunsford <tasa1.army.mil!darl-at-uucp-1.csn-dot-net>
> To: tesla-at-grendel.objinc-dot-com
> 
> To:      grendel!grendel.objinc-dot-com!tesla-at-uucp-1.csn-dot-net 
> Subject: Re: Thunder
> 
> %UNIPLEX
> %TO            grendel!grendel.objinc-dot-com!tesla-at-uucp-1.csn-dot-net
> %FROM          darl
> %SYSTEM        tasa1
> %SUBJECT       Re: Thunder
> %DATE          24/01/96 13:07
> %REFERENCE     13734
> %ADDRESS       grendel!grendel.objinc-dot-com!tesla-at-uucp-1.csn-dot-net
> 
> Subject: Thunder~
> 
>  Why are Tesla coils so noisy?  (Especially running in my basement.)  Is it~
> the same phenomena as lightning & thunder?~
> 
> Ed Sonderman~
> 
> REPLY:~
> i
>    I worked at the physics department of a large university where there was a
> pretty good sized Van der Graaf generator.  Sometimes there was a discharge,
> especially when the system got so dirty from the debris from the belt that it
> cause leakage paths inside the dome.  Although the dome weighed 18-tons and
> was made of some kind of iron or steel-like casting, it could be heard for
> several hundred feet and sounded like an explosion.  
>    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.  These
> pressure variations are in the form of a damped wave and it's for this reason
> we can hear the resounding clap.  If it were just a single "pop" as the media
> collapsed, disregarding that this is mere imagination, it would be so fast
> that it would be similar to static.  However the ripples coming from this
> pressure variation echos back to the hearer and becomes sound.  Remember the
> old cliche:  Where there is no hearer, it's not sound -- just sound waves.~
>    Hope this is not too far afield.  It is bordering on Tesla's experiments
> with the capacitive effect of the ionosphere and the Earth forming a giant
> capacitor where he experimented with world-wide communications and electrical
> energy transfer.  In this light, perhaps it is pertinent.....~
> 
> Bob Lunsford//~
> 
> 
>