The rapid temperature and pressure changes produced by atomic explosions can, in fact, alter the local weather. This isn’t conspiracy theory kookery — it’s actually occurred numerous times in the course of nuclear testing. Here, for example, is an excerpt from a report about Redwing CHEROKEE, a 1956 test of a 3.8 megaton hydrogen bomb:

As the cloud rose and cooled, a very intense purple with Szchrinkoff [sic — Cherenkov] radiation. Rain started in the area at about H+3 minutes after the burst, and at about H+10 minutes, a thunderstorm developed within the stem. Mr. Tanner and I counted 21 flashes appearing exactly like lightning flashes within a cloud.

Lightning accompanied many hydrogen bomb detonations. Ivy MIKE, the first H-bomb, produced quite a lot of lightning, later analysis of the Rapatronic footage found:

That local weather changes would follow nuclear explosions isn’t too surprising when you think about it. What is weather if not pressure, temperature, and electrostatic charge? All three of those things are present in quantity when you detonate a nuclear weapon. I wouldn’t necessarily have guessed, a priori, that rain, lightning, and thunderheads could be created in the immediate aftermath of a nuclear bomb, but after hearing about it, it makes sense.

What’s more surprising, though, is that this was actually investigated as a way to enhance nuclear weapons as early as 1945.

In late April 1945, two theorists working at Los Alamos working on the possible health hazards of the “Trinity” test stumbled upon the fact that rising hot air (such as that produced by a nuclear weapon) might produce rain. They sent a memo to J. Robert Oppenheimer raising the possibility:

After the ball of fire and hot air produced by the gadget explosion start to rise, conditions could easily exist favorable for the formation of a thunderhead. The initial velocity of rise of the hot air should be about 25 meters per second. Hubbard believes that a velocity of only 15 meters per second would be sufficient to produce a thunderhead provided that the atmospheric conditions were just right. He believes that the time when the proper conditions of humidity and instability would prevail over Japanese targets can be predicted accurately. In general they would be quite likely to occur in the summer months,. We are going to make a careful study of this question and its consequences.

Two days later, they sent him another memo, this time discussing raising the possibility of making this happen deliberately. (As a side note, I always love it when the defensive swings around to become the offensive — this might be a problem becomes this might be a cool weapon with amazing rapidity.)

The memo, written by physicist Joseph Hirschfelder, had an ominous title: “Strategic Possibilities Arising if a Thunderstorm is Induced by Gadget Explosion.” Hirschfelder, his 1990 obituary explains, was a leader of a theoretical group at Los Alamos, and later went on to do physics work on the bombs dropped at Bikini in 1946.

Hirschfeder’s 1945 memo explained that “it would be feasible, if desired, to choose the proper weather conditions for delivery [of the bomb] so that the gadget explosion would induce a thunderstorm.” The physics seems fairly clear:

Because of the high potential temperature of the hot air, the active material and fission products would surely rise to heights of the order of 10,000 feet (in a time of three minutes) before the thunderhead would develop. With even a light wind the major portion of the active materials would be carried away from the area of blast damage (for a 15 mile an hour wind, one mile in four minutes) and the products would rain down on an area which has not been severely damaged by the blast (a radius of A damage for blast is considerably under one mile). A simple calculation shows that the radiation from the active material and fission products would be sufficient to to render an area of from one to one-hundred square kilometers uninhabitable. Calculations which I have made on the smoke column would indicate that the radius of our smoke column would be of the order of 500 to 1000 meters therefore we could not expect to poison an area of more than a few square kilometers. …



I do not believe that there would be any lessening of the blast damage if we deliver the gadget in weather conditions favorable for the formation of the thunderstorm (conditional instability, humidity above 60%) and therefore the radiation effects might cause considerable damage in addition to the blast damage ordinarily considered.

In plainer language, Hirschfelder is saying, “hey Oppy, I found a way to make the bomb even more radioactive than we had previously contemplated. We’ll set it off in a way that will create a thunderstorm, which will spread radiation all over the place, even to places that weren’t hit by the actual blast itself.” Clever? Undoubtedly. Horrible? I find it so — it’s an attempt to make the bomb even more unpleasant than it already was. But in a sense, that’s part of the job description, isn’t it?

Hirschfelder closed the memo by offering that, “if you are interested in this possibility, we should try to work out more explicit details: how long it would take before the rain started, how predictable would be the area on which the active material was dumped, etc.” It doesn’t appear that Oppenheimer followed up on the issue, but he didn’t condemn it either. My total speculation is that he never followed up on it because it sounds a little complicated to pull off under wartime conditions — and waiting around for ideal weather conditions was tricky enough as it was without trying to create atomic thunderstorms.

(A small, weather-related meditation: As you probably know, bad weather saved the city of Kokura, Japan, from being the target of the Fat Man bomb. Nagasaki was the runner-up, and even its mission was almost scrapped because of cloud cover. There was probably somebody who lived in Kokura who complained about it being so cloudy on that day, August 9, 1945, without realizing how lucky he or she was. When clouds get you down, cheer up! You might be living in Kokura.)

I came across this memo for the first time while going through the footnotes of Sean Malloy’s excellent article on what was and wasn’t known about radiation effects prior to dropping the bomb on Hiroshima. What struck me about it, aside from the gee-whiz aspect of ATOMIC THUNDERSTORMS, was how bloodthirsty these physicists appeared. Another document from Sean’s article, Bill Penney’s calculations on the ideal height to detonate the atomic bomb (with the special goal of trying to kill as many Japanese firefighters as possible), similarly affected me.

A common depiction is of the Los Alamos scientists as a bunch of giddy geeks whose “technically sweet” lab experiments get appropriated by the military for awful ends. But it’s a far darker story than that. These were some of the smartest people around at the time, and they applied all of their mental energies to the making of war — to the production of deaths. It’s not incomprehensible, of course: they knew they were doing wartime work, and there was, of course, a particularly vicious war on. But the flip side of all of those cute films and photographs of them drinking at lab parties is that when they weren’t there, they were plotting, in meticulous fashion, for killing as many people as were possible. I think we’ve lost some of that in our collective memory. It’s present in some of the earlier depictions of the scientists and their work, but we seem to have compartmentalized our “weapons scientists” into the “good guys” (Oppenheimer, Bethe, Feynman) and the “bad guys” (Teller, Von Neumann) in terms of who we think are more dovish or hawkish. And yet, they all made weapons of mass destruction — some with more ambivalence than others, but they made them nonetheless. I’m not a total dove about these things, but I still think it’s worth keeping that at the forefront of one’s mind when talking about these guys. What I think is easy to forget when we read about Feynman’s hijinks and Oppenheimer’s highballs is that these geniuses were applying the entirety of their brains to a very grim job, one they did quite well. It is impossible to imagine the military men thinking up atomic bombs — much less atomic thunderstorms — on their own.

Tags: Bad ideas, Hiroshima, J. Robert Oppenheimer, Los Alamos, Manhattan Project