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(meteorobs) Atmospheric expansion and meteors
Tom Ashcraft wrote:
>Also as I understand it the outer edge of the ionosphere at solar minimum
>is about 80 kms out but during solar maximum the outer edge is 140 kms or
>so out.
>Wouldn't this sky expansion mean that more meteors are intercepted or is
>this all negligible?
Ionosphere means the part of the atmopshere where the abundance of free
electrons causes some conductivity. The range where the electron density is
large can vary strongly with solar activity. For meteors I think the main
parameter is the air density which the particle with cosmic velocity faces when
entering the atmosphere. This density varies much less distinctly than the
free-electron density. The free-electron density is between 10^10 to 10^11
electrons per cubic meter. The molecular density, however, is about 10^19
molecules per cubic meter, i.e. at least
100 million times higher. So the meteoroid will not see any difference between
high or low ionosphere when entering the atmosphere. The only thing that could
be affected is the ionisation and recombination of air molecules, i.e. the
luminous process of the meteor. I guess we may expect brightness variations with
different free-electron densities, but also guess they are extremely small.
Ionosphere expansion does not mean the atmosphere expands -- the range where
free electrons can be found varies.
Rainer
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Rainer Arlt -- Visual Commission Director
International Meteor Organization
100114.1361@compuserve.com
Home page of IMO: http://www.imodot net
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