[meteorite-list] Seems PF fell on 3/27 and NOT on 3/26...

From: Frank Prochaska <fprochas_at_meteoritecentral.com>
Date: Thu Apr 22 10:22:38 2004
Message-ID: <NDBBICFKNKHAAEEJLDALEEICDJAA.fprochas_at_premier1.net>

Hello all,

I don't believe the point of Mike's post had anything to do with the
elevation of the terrain in the Park Forest area. The density of the
atmosphere continues to increase as you travel from above to lower
elevations. The rate of decrease of the cosmic velocity of a meteoriod
increases proportionally, and eventually all of the cosmic velocity is
eliminated (at for all intents and purposed the point of extintion) and the
meteoriod continues in free fall (terminal velocity). Only very large
bodies retain portions of their cosmic velocity all the way to the ground,
and these bodies would therefore be a true "meteor" and show "flame" all the
way to the ground as well as be true cratering events. The mass of PF was
clearly not anywhere close to the size required for this. But if the point
of extinction of PF was only 7000 feet, for a relatively "normal" meteorite,
Mike's point is that, with the elevation of many parts of the Earth in that
range, we should see similar "normal" meteorites landing in these parts of
the world with remnants of cosmic velocity, still ablating with very high
surface temperatures, and so indeed setting grandpa's haybales on fire at
that surface elevation, among other dramatic consequences. I think Mike is
simply pointing out that this is not what we see, and that the extinction
point for PF sized meteorite must be much higher than 7000 feet.

Frank Prochaska





-----Original Message-----
From: meteorite-list-admin_at_meteoritecentral.com
[mailto:meteorite-list-admin_at_meteoritecentral.com]On Behalf Of Sterling
K. Webb
Sent: Friday, June 13, 2003 9:07 PM
To: Michael Farmer
Cc: MeteorHntr_at_aol.com; meteorite-list@meteoritecentral.com
Subject: Re: [meteorite-list] Seems PF fell on 3/27 and NOT on 3/26...


Hi,

    If we're talking about Illinois and the Chicago area here,
the elevation of Lake Michigan at Chicago is 597 feet. In
general, the lay of the land throughout the state is to gently
decline to the south. Illinois is essentially flat. The elevation
of the Mississippi at St. Louis is 440 feet and so on. The
highest elevation in Illinois is in the far-off northwestern
tippy-tip at 1235 feet, but that is a Wisconsin hill whose crest
is a few thousand feet over into Illinois.


Sterling K. Webb
----------------------------------------------------------------------------
--------

Michael Farmer wrote:

> there is no possibility that the fireball extuinguished at that
> low level. It was bright enough to iluminate through the thin
> cloud layer. Many parts of the country are higher than 7000
> feet. If that were the case, then many meteorites would indeed
> set grandpa's haybales on fire!
>
> Mike Farmer


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Received on Sat 14 Jun 2003 12:47:42 PM PDT