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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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