(meteorobs) thoughts, please

Bias, Peter V pbias at flsouthern.edu
Fri Sep 15 15:11:48 EDT 2006


Dale and all,

Alas, again, no pros seem to be taking on a question for us, so I'll
give it a try:

Right off the bat, in number 3, a "meteorite" cannot be repelled into
space by the atmosphere because a meteorite is defined as having stuck
the ground.

Also in 3, I'm not sure what "turned aside" means although there are
instances when meteoroids have hit the atmosphere and skipped away. The
daylight fireball in August 1972 (I think that's the year) was filmed
doing just that.

>From number 1, most authorities will quote that meteors become visible
at closer to 100 km rather than to 200 km. At some 125 miles up (roughly
200 km), there isn't a lot of air to stop anything. "Violent
displacement" by upper atmosphere winds is not referenced anywhere that
I've seen. I have no idea whether winds are coming out of the west
everywhere in the atmosphere, (presumably that's what it would take to
"displace toward the east") but it doesn't sound right at first blush.
Is this maybe a reference to diurnal aberration, which is the change in
the apparent path due to earth's rotation?

I certainly hope others will tackle this question (and not leave me
hanging!). 

   Pete Bias



> -----Original Message-----
> From: meteorobs-bounces at meteorobs.org [mailto:meteorobs-
> bounces at meteorobs.org] On Behalf Of Dale
> Sent: Thursday, September 14, 2006 6:36 PM
> To: meteorobs at meteorobs.org
> Subject: (meteorobs) thoughts, please
> 
> the following is quoted from an author of some standing, and some
> controversy.  for the latter reason, i choose not to identify the
author
> for the moment.
> 
> please consider the quote and advise any errors that you find.
> thank you
> dale botwin
> miami fl
> a..
>   1.. Meteors, after entering the terrestrial atmosphere at about 200
km.
> above the ground, are violently displaced toward the east. These
> displacements of the meteors are usually ascribed to winds blowing in
the
> upper atmosphere.(24) The atmospheric pressure at a height of 45 km.
is
> supposed to be but "a small fraction of one millimeter of mercury."
(25)
> On the other hand, the velocity with which the meteors approach the
earth
> is between 15 and 75 km. per second, on the average about 40 km. per
> second or over 140,000 km. per hour. If winds of 150 km. per hour
velocity
> were permanently blowing at the height where the meteors become
visible,
> it would not be possible for such winds of rarefied atmosphere to
visibly
> deflect stones falling at the rate of 140,000 km. per hour.
>   2..
>   3.. Approaching the earth, the meteorites suddenly slow down and
turn
> aside, and some are even repelled into space. "A few meteors give the
> appearance of penetrating into our atmosphere and then leaving it,
> ricocheting as it were." (26)
> ---
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