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Re: (meteorobs) Excerpts from "CCNet 97/2000 - 28 September 2000"



Lew:

It will depend on the height at which ablation occurs. MFP's of order 10cm are
typical at higher meteor ablation heights, so essentially all 'typical' visible
meteors are in free molecular flow.

Peter

Lew Gramer wrote:

> Dr. Peter Brown writes:
> >John Lewis and Jim Oberg are correct for LARGE objects. However, for most
> >(smaller) meteoroids where the atmospheric mean free path is larger than the
> >characteristic size of the body no air cap forms as the flow is free molecular
> >(as opposed to continuum). In this case individual air molecules may collide
>
> Peter, this was what I vaguely recalled from my (amateur) reading of Oepik's
> "Physics of Meteor Flight in the Atmosphere"! Do you happen to know off-hand
> the meteoroid characteristic sizes for this important cut-off point between
> continuum and free molecular flow? I recall in Oepik it was quoted as being
> quite tiny - smaller than observable size limits for most meteoroid streams.
> Is this still thought to be the case?
>
> Just a curious question, thanks for the reply!
> Lew Gramer
>
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--
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Dr. Peter Brown
Assistant Professor
Meteor Physics Group
Department of Physics and Astronomy
University of Western Ontario
London, Ontario
N6A 3K7
Canada

http://phobos.astro.uwodot ca/~pbrown
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Fax:1-519-661-4085
email:pbrown@julian.uwodot ca
Meteor Astronomy Lab : 1-519-661-2111 x84744
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