(meteorobs) Why do some meteors appear to zig-zag? Wavering sounds

Wayne Watson sierra_mtnview at earthlink.net
Thu Jul 8 21:05:07 EDT 2004


On the topic of experienced observers, a few weeks ago the Science Channel (old 
Discovery) had a program on classified and futuristic aircraft. One fellow in England 
talked about how he had seen an enormously fast aircraft off the coast of England. He 
remarked that he was confident it was an aircraft unlike any he had seen. His 
qualifications? He was a RAF military aircraft spotter, and to qualify they have to 
be able to identify any aircraft (friend or foe) in 5 seconds or less. I believe that 
may be without binocs or telescopes.

E. L. Jones wrote:

> Hello Lew,  Gang.
> 
> I understand well the tendancy for the human mind to fill in the blanks 
> when it comes to recalling fast paced phenomena.  I'd like to believe 
> that I am a bit more experienced observer than the average fireball 
> reporter and I try to accurately sense fast moving situations.  I have 
> heard a sequence of sounds from a meteor that didn't include a sonic 
> boom, a bolide burst, nor electrophonic sounds.
> 
> April 23, 2000 around 3:10 in the afternoon I was in my yard here in the 
> Poconos of Pennsylvania and heard the transit of what I believe to be a 
> fast moving meteoroid.  I say "heard" because I didn't see it.  Owing to 
> the fast transit and apparent  25-35° down angle , I excluded an 
> aircraft(no engine sound),  rifle bullet (trajectory wasn't flat enough) 
> or a part falling from an aircraft (trajectory was too fast and not 
> vertical enough) .  The object produced a whoosh sound constantly but 
> had an embedded whap.......whap,whap....whap.......whap,whap sound.  I 
> presumed this to be a tumbling object with three prominences which 
> changed pitch as it tumbled in the slipstream.
> 
> As to  potential mechanisms, one which is not likely at play this time 
> here is the advance and retreat of a helicopter blade tip can break the 
> sound barrier on the forward motion while falling below that threshold 
> on the rearward movement.  The result is a series of sharp cracks when 
> the conditions are right.  I could imagine a meteoriod in dark flight 
> while still supersonic to produce different shock waves if it were 
> tumbling.
> 
> I think the category of sound I heard is due to tumbling at high speed.  
> A tumbling artillery or mortar canister--after releasing a parachute 
> flare, will produce a similar wavering pitch. Shrapnel will also produce 
> a distinctive sound.  Large caliber aircraft cannon cases have a 
> distinctive sound differing from smaller cases.  In parachute training 
> at Ft Benning, the instructors used to guess what was falling from basic 
> parachute trainees as they exited the aircraft and lost equipment from 
> their packs.  Each category of object, coin, ripcord handle, helmet, 
> camera whatever, have different sound signatures. Most everything 
> produces a constant whoosh sound.  Anything may produce a series of 
> sounds if they are tumbling relatively fast against an airflow( 
> turbulent vs laminar flow). Objects down to a foot long or so can be 
> heard kilometers from where they are falling.  I believe the ultimately 
> we will find that the subsonic (and perhaps supersonic) sounds vary with 
> the cross section facing the windward side, peaks and hollows on the 
> surface
> 
> So, after what I have seen--I mean "heard"  happen, and taken with other 
> reports by close witnesses who reported a whoosh as a meteoroid passed 
> near by, I believe that meteoroids can and do produce subsonic wavering 
> sounds.  I believe this is technically due to rapidly changing cross 
> sectional aspect in the slipstream or in lay terms-- tumbling cartwheels 
> like crazy.
> Now after all this showing off I've done  as I reread your post, is it 
> only simultaneous sounds wavering that your comment was about?  Arrrghhh
> 
> In that case it still could be due to tumbling if the tumbling changes 
> the output of the plasma envelope by deflecting it or uping the output 
> as more cross section is stuck out into the stream.  If the 
> electrophinics are induced by Radio Frequency (RF) waves chances could 
> be that the tumbling is acting on the RF emissions much like tunning an 
> antenna etc.
> 
> Regards,
> Elton
> 
>> Date: Wed, 7 Jul 2004 17:55:32 -0400
>> From: "Lewis J. Gramer" <lgramer at upstream.net>
>> Subject: Re: (meteorobs) Why do some meteors appear to zig-zag?
>>
>> <snip>
>>
>> BTW, MexicoDoug, I also found your post interesting - although it does 
>> raise
>> questions in my mind at a couple of points. For one, I noticed that 
>> the reports
>> you cite mention "sounds" heard during the fireballs witnessed: though 
>> there
>> is good evidence now that simultaneous or "electronphonic" sounds are 
>> in fact
>> real observable phenomena, I have never heard any potential mechanism for
>> these sounds, which would allow a rotating meteoroid to result in 
>> "wavering"
>> or otherwise changing sound heard simultaneously on the ground... Does 
>> anyone
>> else have any information on this particular point?
>>
>> In fact, if anything, the fact that these sounds are mentioned in the 
>> reports
>> cited, might SEEM to indicate that the reporting observers were either:
>> a) reporting something much closer to them than a meteor, e.g., 
>> fireworks;
>> or,
>> b) very "suggestible", in their recollections of what they observed.
>>
>> In any case, thanks to all who have posted so far on this thread: 
>> during the
>> times between major showers, it's always interesting to bring up these 
>> old
>> chestnuts from past years' debate on 'meteorobs'. :)
>>
>> Clear skies!
>> Lew Gramer
>>  
>>
> 
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-- 
                  Wayne T. Watson (The Wizard of Obz, Nevada City, CA)
                     (121.015 Deg. W, 39.262 Deg. N, 2,701 feet)
                -- GMT-8 hr std. time, RJ Rcvr 39° 8' 0" N,  121° 1' 0" W
             (Formerly Homo habilis, erectus, heidelbergensis and now sapiens)

               U.S. rank in science education in 1970: 3. Rank in 2004: 23.
               1/2 of our graduating engineering students are foriegn born.
                                 --  Source, NY Times

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