ecl@hocsj.UUCP (10/10/84)
Those funny lines: I have seen a fair amount of documentary footage showing above ground nuclear explosions. Some seem to have some peculiar vertical, white vapor trails before and after the explosion. The usually go off to the left of where the bomb goes off and are very much evenly spaced. My guess is that they are intended to give scale to the films taken of the detonation, but I have never gotten any confirmation of this. Anyone out there know what I am talking about? (Evelyn C. Leeper for) Mark R. Leeper ...ihnp4!lznv!mrl
jimb@amd.UUCP (Jim Budler) (10/12/84)
... > I have seen a fair amount of documentary footage showing above ground > nuclear explosions. Some seem to have some peculiar vertical, white > vapor trails before and after the explosion. The usually go off to the > left of where the bomb goes off and are very much evenly spaced. ... Air can only move and compress at a limited rate when compared to the speed of the shock wave from the nuclear explosion. As a result standing waves ('pressure fronts') are created in the air. At the dividing line between the high and low portion of the standing wave 'clouds' are formed, thus your vapor trails. As for the even spacing that is due to the mathematics of the limiting velocity of the air molecules vs. the pressure front vs. viewing distance vs. predominating wavelength of viewing light. The vertical, as opposed to circular, horizontal, etc. is probably a matter of point of view. A down shot of the explosion over an even colored terrain would probably show circular rings. The shockwave probably travels to the limit of the atmosphere VERY quickly relative to the horizontal speed so you aren't as likely to see dome shaped shock waves. ( Very early, just after ignition, picture might show a dome pattern). Pattern on the left of the mushroom vs. on the right? I don't know but perhaps this relates to the position of the sun compared to the photographer and the mushroom. Since most of the newsreel photos come from the same testing grounds, and usually the tests were probably in the afternoon, the sun would be on the same side relative to the photographer even for different tests (permanent photo bunker). All of this is probably the subject of hundreds of classified research projects costing gigabucks. -- Jim Budler Advanced Micro Devices, Inc. (408) 982-6547 UUCPnet: {ucbvax,decwrl,ihnp4,allegra,intelca}!amd!jimb Compuserve ID: 72415,1200
hlee@hplabsb.UUCP (Ho John Lee) (10/12/84)
The US Government Printing Office publishes a book called
"The Effects of Nuclear Weapons." I think it was last revised
around 1978. It is a compilation of (unclassified) results from
all those test blasts in the 50's and 60's. There is a fairly
long chapter about the effects of shock waves in land, water, and
air, but I don't remember whether they talk about vertical lines.
Anyway, it's full of information, (~300pp, hardbound), cheap ($14.95),
and you also get one of those "Dr. Strangelove" bomb effect calculators
to scare your friends with ("Let's see...100KT air burst at 6000 feet...").
--
Ho John Lee, HP Labs
UUCP: ...!hplabs!hlee
ARPA: hlee.hplabs@csnet-relaymikel@bmcg.UUCP (10/12/84)
In article <hocsj.170> ecl@hocsj.UUCP writes: >I have seen a fair amount of documentary footage showing above ground >nuclear explosions. Some seem to have some peculiar vertical, white >vapor trails before and after the explosion. ...... > > (Evelyn C. Leeper for) > Mark R. Leeper > ...ihnp4!lznv!mrl I have also noticed them. I have always assumed that they are generated by small rockets, and that the vapor trail are used to study the blast pattern and the mushroom cloud wind currents. I don't know anyone who knows for sure. [Row, row, row your bits, gently down the stream...] Mike Lesher Burroughs ASG, San Diego, CA. (..!bmcg!mikel)
wmartin@brl-tgr.ARPA (Will Martin ) (10/12/84)
I always thought that those were smoke trails left by rockets, sent up just prior to the blast, to give visual evidence of the shock waves and other air movements caused by the explosion. I have a vague recollection of reading that somewhere, maybe just in a photo caption. I, too, would like to know for sure. Will Martin USENET: seismo!brl-bmd!wmartin or ARPA/MILNET: wmartin@almsa-1.ARPA
rpw3@redwood.UUCP (Rob Warnock) (10/13/84)
+--------------- | Air can only move and compress at a limited rate when compared to | the speed of the shock wave from the nuclear explosion. As a result | standing waves ('pressure fronts') are created in the air. At the | dividing line between the high and low portion of the standing | wave 'clouds' are formed, thus your vapor trails. +--------------- Gee, and I always thought those vapor trails were the smoke-emitting weather rockets they shot up just before the blast to create visible markers so the pretty pictures could record the shape of the blast waves. (They also do something similar with colored smoke trails on towers to look at vortex patterns behind jumbo jets. See the pretty picture on the cover of Scientific American a while back.) Does anybody out there KNOW what they were (instead of all our guesses)? ;-} Rob Warnock UUCP: {ihnp4,ucbvax!amd}!fortune!redwood!rpw3 DDD: (415)572-2607 (*new*) Envoy: rob.warnock/kingfisher USPS: 510 Trinidad Ln, Foster City, CA 94404 (*new*)
gwyn@brl-tgr.ARPA (Doug Gwyn <gwyn>) (10/14/84)
Yes, those vertical trails are for calibration of photographs.
lkk@mit-eddie.UUCP (Larry Kolodney) (10/14/84)
I beleive that vapor trails are put their by overflying planes so that
when the bomb goes off, they can judge the intensity by how much the
trails are displaced by the blast.
--
larry kolodney (The Devil's Advocate)
UUCP: ...{ihnp4, decvax!genrad}!mit-eddie!lkk
ARPA: lkk@mit-mcmp@u1100a.UUCP (Mike A Pilla) (10/15/84)
Those funny white lines were the trails of "smoke rockets" deliberately
launched just before firing of the device so that the "shock waves" could
be seen.
--
Michael Pilla
Bell Communications Research
201-981-7290
{ihnp4,allegra,pyuxww}!u1100a!mp