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(meteorobs) Meteorite Detection
I suppose most of you already sub to Scientific American and so probably
have seen the excerpt below. But for those who have not, have a look. Bear
with the initial seemingly-off-topic comments because the "punch line" is
near the end of the article.
Clear skies,
SteveH
Shreswbury MA
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>Date: Sun, 31 May 1998 23:07:38 -0500
>From: Lawrence Stoskopf <stoskopf@tridot net>
>X-Mailer: Mozilla 4.05 [en] (Win95; U)
>To: farmnet <farmnet@rf.org>, microwave reflector <microwave@wa1mba.org>,
> lwcanews@aol.com
>Subject: Microwave: Sensing Subtle Tsunamis
>Sender: microwave-reflector@wa1mba.org
>Reply-To: Lawrence Stoskopf <stoskopf@tridot net>
>
>Sorry for the multiple postings, but in a bit of schizophrenic thought
>while gardening thought this might hit a sensitive spot with someone
>else:
>
>May 98 Scientific American in The Amateur Scientist has an article on
>measuring very slow changes in atmospheric pressure. The contents of
>the article are found at:
>
>http://web2.thesphere.com/SAS/
>
>It is an interesting way to measure air pressure changes with resolution
>in the 20 microbar range! Being an anesthesiologist and not a
>feedback/control engineer the inherent feedback damping must be
>interesting to model and I keep thinking that there is an easier way
>today.
>
>But why is this of interest? In the same magazine in a monthly column,
>Wonders, by Philip Morrison, a scientist of some reput, the subject is
>Double Bass Redoubled.
>
>Key words: Infrasonics. "Microbaroms ...peak at frequencies of 0.2 to
>0.3 hertz...The infrasonic domain now under study begins an octave lower
>than that....A whole menagerie of large-scale eventss generates
>infrasound at a distance....Volcanic eruptions, meoteoric
>fireballs....dot detection begins with a quiet countryside site, a good
>capacitance microphone and a modest amplifier designed to work well at
>frequencies from a fwe tens of millihertz up to about 0.1 hertz. A
>noise filter against local wind noise is realized by a dozen simple
>pourous hoses that extend from the microphone into yards-long spokes.The
>infrasound energy density flowing undetected from a volcano far overseas
>matches roughly the energy flow from an ordinary whisper at your
>side....
>
>Great stuff in between, but this is the punch line:
>
> "Pressure waves from fast-moving meteorites high aloft often span
>the globe at still lower frequencies. The physics of such sound, called
>acoustic-gravity waves, are rather different. These waves are five to
>10 miles long..... It won't be too long until these sounds from afar can
>help us complete the reliable world census of incoming large meteorites
>that so far we lack." (end of article)
>
>Leonids Nov 17 for a possible 33 year peak. A way of measuring what the
>guys in Asia are getting before we rotate around. Might be something to
>discuss at the CSVHF conference in July. The lowfers already dabble in
>such.
>
>Ok, I'm doing giving an anesthetic for an ECT for depression tomorrow at
>7A, shall I ask the shrink to add lithium to my diet?
>
>N0UU
>
>