(meteorobs) thoughts, please

[Marco Langbroek]

Dale wrote:
> 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. 

First sentence not true, follow up reasoning correct.

>   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)

Not ricocheting. Some graze the upper atmosphere only at nearly zero angle and 
as this upper atmosphere is following the earth curvature, it means they enter, 
and as the atmospher curves away under them, leave again. This is rare to happen 
though. A famous example is the 1972 Grand Tetons fireball.

- Marco

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Dr Marco Langbroek
Dutch Meteor Society (DMS)

e-mail: meteorites at dmsweb.org
private website http://home.wanadoo.nl/marco.langbroek
DMS website http://www.dmsweb.org
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