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Re: (meteorobs) Fireballs & sonic booms
In a message dated 99-07-01 19:22:56 EDT, you write:
jure<<
How bright should a fireball be to produce sonic booms and how deep into the
atmosphere should it penetrate? I'm just curious, so that I can know when I
can shout and jump around after a fireball or should stay quiet for a couple
of minutes.
>>
Jure, If the fireball occurred somewhere in the vicinity above you and was
about -8 or brighter, you ought to refrain from jumping, shouting and other
gyrations for up to about 3 minutes. You might hear some sonics if the object
reached an altitude of around 30 miles above the earth. If you ever heard an
airplane break the sound barrier, that is what it sounds like. Though
sometimes if they reached below the approximate 30 mile marker and is some
distance from you down range, you might hear some rumbling or perhaps a
distant popping noise. Listen for these up to about 5 minutes after the
appearance of the fireball. Usually I wouldn't expect any sonics from a -8,
but magnitude judgements get a little off at about that range. It might
actually be brighter than you think? Usually though people will mis-judge the
magnitude towards being a little brighter than what it actually is. Anything
over -10 in magnitude has potential to produce sonics though not all will.
There were sonics in the Peekskill fireball and it was judged to have a
magnitude around -13. Of the two that I heard, one I seen visually and i gave
it a magnitude of -15. The other one I only heard while napping, but from
the reports of those who seen it, it was probably at least a -12. It sounded
like someone was blasting with dynamite relatively close. At the time that
is what I thought it was, since I didn't see it as a meteor to make a
connection.
GeoZay
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