🚀 go-pugleaf

Rich Silva [rich@locus.com] wrote:
>I was in Joshua Tree national forest last May when I saw a plane in the upper
>atmosphere fly across the sky about as fast as metors do I didn't here any
>sonic booms but I't couldn't have been a jet airliner it was moving too fast
>I did notice it's contrail was lumpy like -+-+-+-+-+-+ like a pulse.

a possible reason why you didn't hear anything {i.e. no sonic boom, and no
thrust noise} was that the sound from the mach cone and from the jet was
refracted too much away from the ground due to a sound speed profile in the
atmosphere:  the sound speed for the *aircraft* altitude was slower than the
speed of sound on the ground, so the sound waves refracted enough for you to
be in an acoustical shadow zone.  the same phenomenon exists in the ocean.  of
course, maybe you really didn't see anything at all   :)     -ken
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    |    R  2	      Real Monza	     kdrolt@athena.mit.edu    |
    |    |__|					grad student !!       |
    |    |  |	'64 Corvair Convertible      mit ocean engineering    |
    |    1  3					underwater sound      |
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