Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.2 9/18/84; site amd.UUCP Path: utzoo!watmath!clyde!amd!jimb From: jimb@amd.UUCP (Jim Budler) Newsgroups: net.physics,net.misc Subject: Re: Those funny lines Message-ID: <412@amd.UUCP> Date: Thu, 11-Oct-84 19:51:12 EDT Article-I.D.: amd.412 Posted: Thu Oct 11 19:51:12 1984 Date-Received: Sat, 13-Oct-84 07:18:46 EDT References: <170@hocsj.UUCP> Organization: AMD, Santa Clara, CA Lines: 40 ... > 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