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(meteorobs) Re: Meteorite temperatures, etc.
I have been following this discussion regarding the temperature of
meteorites on impact. There is no easy answer to this! Most every one has
assumed that a meteoroid is a very cold body before it enters the
atmosphere. This is not necessarily the case. Was the meteoroid on the sun
lit side before entry? If it was, how much heat did it absorb from
sunlight. This would depend on the albedo of the meteoroid, whether it was
rotating or not, the type of material etc. Iron meteoroids would transfer
heat more easily than a stone meteoroid and a dark bodied one would absorb
more heat. Temperature on impact also depends on the duration of time
elapsed during its supersonic flight. Friction heating plays a roll at
these speeds even after ablation has ceased. Ablation is thought to have
ceased at around 3 km/sec. Some say this may be as high as 6 km/sec so
friction heating is still a factor at these velocities. Entry temperatures
of meteoroids entering the earths atmosphere can be quite different
depending on all of the above. One thing we know for sure is that there is
no CONFIRMED record of a normal sized meteorite ever starting a fire. Some
can be quite warm however and others may indeed be covered with a layer of
frost. More study is needed on this but unfortunately few meteorites are
picked up seconds after impact.
Ed Majden
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