“Tanks, jeeps and other test vehicles litter the desert floor milliseconds before the force of the explosion destroys them. Just below the bottom of the fireball, a crescent-shaped shock wave has bounced off the desert floor and is merging into the expanding nuclear fire.” From the New York Times slideshow, Capturing the Atom Bomb on Film. Image taken from Peter Kuran’s book, How to Photograph an Atomic Bomb.
Related: Exposure and Atomica!
Ah, the Mach stem effect – http://www.atomicarchive.com/Effects/effects6.shtml
The combined reflected and incident shock waves combine and double the destructive effect. As the shock wave expands outward the reinforecemt effect lifts off the ground, and may result in oddities at extended distances such as the top of a radio tower sheared off while things on the ground are relatively unharmed.
I recall reading about it in a copy of “The Effects of Nuclear Weapons” checked out from the public library system in Montgomery County Maryland, ca. 1970, a thick pamphlet-style text with hand-drawn illustrations.
http://www.amazon.com/EFFECTS-NUCLEAR-WEAPONS-Samuel-Glasstone/dp/B000GU836C/ref=sr_1_3?s=books&ie=UTF8&qid=1289627707&sr=1-3
Incredible photo.
I’d imagine “Stand Well Back” is covered early in Chapter 1.
Actually, they seem to have left that bit out judging by the blokes in lumberjack shirts standing half a mile away in one of the pictures!
Stunning collection of photos. The shot of VIPs sitting in comfy chairs watching a blast as though it’s a sitcom on TV is quite something.
Baz,
Yes, it’s rather like they’re at a 3-D test screening.
Though my favourite atomic story involves Ted Taylor, a miniaturisation expert who worked on many of the early atmospheric experiments. On June 5th, 1952, during the test explosion of a 14 kiloton device in the Nevada Desert, Taylor used a parabolic mirror to focus the bomb’s glare and light his cigarette.
Which officially makes him the coolest hombre ever.
Regarding the apparent distance of observers from ground zero, the possibility of a foreshortening illusion from use of a telephoto lens in some cases should be considered.
But of course, there were times when people were right in there. Soldiers in slit trenches in at least one test. In the Pacific, sailors were close enough to have pulverized coral rain down on them. The things that were not known, the justification of preparing for possible apocalyptic war… God forgive us.
I knew a guy whose step-father was a civilian Navy employee, a physicist who studied blast effects. He was stationed on ships at some of the early Pacific tests. A few daring souls (he described them as “fearless”) would don protective gear, get in speedboats, and drive out into the disturbed area immediately after the detonation in order to gather samples. He recalled people returned from sampling, in full protective garb, running down the ship’s corridor to reach a decontamination area, one guy yelling “Stay back, I’m hot, I’m hot.” I always wondered if somebody mopped the hallway right after – I forgot to ask. I would guess they had been given a preliminary hosing-off before they got on-board. I hope so. (The Step-father lived to a ripe old age, by the way.)
Wm T Sherman: one of my most prized possessions is a copy of ‘The Effects of Nuclear Weapons’. It even has the original disc calculator tucked in the pocket in the back. It cost a bomb (hur hur) but it’s endlessly fascinating. One of the first programs I wrote for the Apple Macintosh was a distillation of its various charts and nomograms. The trend has been over the last few decades to move away from the multi-megaton city-busters that both we and the Russians fielded because they had CEPs of miles rather than metres, but a W88 warhead (Trident D-5) still yields 475 kT. It really does bring home the essential verity of that old bumper sticker: “One nuclear bomb can ruin your whole day.”
If you’re outside the danger zone for heat and blast, then the damage you’ll suffer from prompt radiation is pretty low (at least for big bombs). It’s only really towards the low yield end that you find significant radiological casualties who haven’t also been cooked or flayed into offal by flying debris (which was of course the rationale behind enhanced radiation weapons AKA neutron bombs: to kill Soviet tank crews in their armour by neutron spallation.) Fallout is of course a serious problem, especially for surface bursts, but if I were actually witnessing a nuclear blast the only thing that would cause me any concern is prompt gamma.
Prompt gamma = rads in the ‘nads, per nuclear industry parlance.
The Russians did an exercise in Semipalatinsk in the fifties which involved dropping a bomb, and then (half an hour later) sending an infantry regiment through ground zero.
I still remember NBC drills, and immediate action (IA) for a nuke – ‘Stick your head between your legs and kiss your arse goodbye’.