Dressing for the H-Bomb

Nuclear_fireballAs the Station Fire still lingers over these last weeks, only now finally almost fully contained, I’ve pointed many folks to the dramatic images of the pyrocumulus clouds that have come out of it, especially the time-lapse images of these clouds developing.  Like many folks new to having such large fires quite so close, I only learned about the pyrocumulus mechanism with this fire.  One thing that is dramatic in this phenomenon (apart from the sufficiently dramatic itching eyes, headaches, and sore throats that all my friends seem to share) is its striking resemblance to an H-Bomb blast.

I am not the first to note this resemblance, of course.  Not even the first Metblogs author to do so.  Nor the first to think and write about the identity of the thermodynamic mechanism of the formation of an H-Bomb’s mushroom cloud over the course of seconds, and the fire’s formation of one over the course of days or weeks.

Aug2009_LA_FireOne thing I have not seen specifically compared, however, is the scale of the two events.  I figured it was time to grab the back of an envelope.  Just how much explosive power is a megaton of TNT, as the bombs are measured? Well, it turns out that the National Institute of Standards and Technology has actually defined the canonical yield of a gram of TNT as 4,184 joules.  Grams add up to kilograms, kilos to tons, and tons to megatons.  Simple enough multiplication.  What about fires? Just how much flammable material is there in 160,357 acres? What is the energy content of that material when burned? Lots of web sources helped me find approximate values all around, and multiply lots of numbers together.  Sparing readers most of the steps, my not-completely-wild-assed estimate here is that the Station Fire amounted to the same energy yield as 3 megatons of TNT.  Not the biggest H-Bomb built, but solidly in H-Bomb territory.

What does it all mean? I dunno.

Somehow the equivalence, however, makes me think of a point made by Thom Andersen, in Los Angeles Plays Itself, which I had the pleasure of seeing a few weeks ago at the Aero Theatre in Santa Monica, with live questions and answers with the writer/director.  Andersen observes, among many things in his essay-as-film, how often Los Angeles plays the scene of post-apocalyptic disaster, and how well suited to this role are the desolate downtown neighborhoods such as Bunker Hill.  Part of this type casting is, no doubt, a certain Weltanschauung of audiences and producers about Los Angeles.  Andersen notes,

Mike Davis has claimed that Hollywood takes a special pleasure in destroying Los Angeles, a guilty pleasure shared by most of its audience. The entire world seems to be rooting for Los Angeles to slide into the Pacific or be swallowed by the San Andreas fault.

However, beyond the appeal of German words (Schadenfreude comes to mind here as well), there is a whole lot Los Angeles does to choose its roles, and type cast itself.  The first times I ever walked around Downtown at night, I was shocked, perhaps mortified, at what appeared to every examination, to be the ruins of a once populated and great city.  But a city that had been stripped of its inhabitants, leaving only vacated concrete and steel.  I’ve lived in small towns that closed at 9:00 p.m.; somehow I didn’t expect the second largest city in the United States to be one of them.  A slow motion Armageddon is just, like, totally L.A.  Or in a line from Buffy, “I never thought I’d need to learn the plural of apocalypse.”

Andersen continues:

The end of Bunker Hill is visible in The Omega Man. By 1971 it made a good location for a post-apocalyptic fantasy. Charlton Heston plays an urban survivalist in a cityscape depopulated by biological warfare. He has learned to become totally self-reliant. If he wants to see a movie, he has to project it himself. […]

Thirteen years later, the same plot and the same location reappear in Night of the Comet. In the wake of a disaster apparently brought on by comet dust, a small band of human survivors again battle zombie-like mutants, but the center of the action, Bunker Hill, has been totally transformed.The new Bunker Hill looks like a simulated city, and it played one in Virtuosity.

Was it Hollywood that started the Station Fire, as a means to insist that life must follow its “art?!”

5 Replies to “Dressing for the H-Bomb”

  1. Great post, And as an FYI the various fire helicopters are still buzzing my ‘hood filling up with water to deal with the fire. We still are getting a fine ash “fall out” which is making a gritty mess of everything.

  2. A lot to ruminate on here, but I’m not sure if the energy released in a forest fire could be seen as comparable to that in a bomb because of the time it took for the material to burn.

    As for imagining LA’s destruction and delighting in it, in the California studies classes I taught, I liked to bring up the point that when New York City is destroyed in films, it’s always tragedy, but when LA is destroyed, it’s anything but. Think back to Independence Day, when the destruction of LA is represented by a bunch of ditzy people on top of the Library Tower welcoming the aliens. So not only are we all killed, we deserved to be killed because we’re stupid, and it’s played for laughs.

  3. Well, the energy is directly comparable, in the plain sense classical mechanics. Remember your high-school Newtonian formulas:

    force = mass x acceleration
    energy = force x distance

    Notably also:

    power = energy / time

    There’s no time component in energy (well, there is buried in acceleration; but it’s not the “main” thing like in power). If you compare power, on the other hand, the H-Bomb releasing all that energy in microseconds is vastly more than the fire doing it over weeks. I.e. dividing by 1ms makes a much bigger number than dividing by billions of ms’s.

    Clearly, the destruction from the different events is not the same. Giving the energy time to diffuse makes a difference. And it is easier to evacuate with a day’s notice than with a millisecond notice. And lots of other differences.

    Moreover, lots of things add up to the same power given the right time. The energy of solar radiation hitting Los Angeles exceeds that of an H-Bomb if you give it the right amount of time. I haven’t done the back of envelope, but I bet that time frame is less than most people might guess (maybe a reader will calculate this). And y’know sun=good; while fire/bomb=bad.

  4. OK, not one to leave questions unanswered. Just how much energy is in sunlight?

    It turns out that I found an estimate that an acre of solar cells produces about 440,000 watts. Which is to say, 440k watt-hours in an hour. Since we all know that there are 3597 joules in a watt-hour, the comparison is pretty easy. Of course, solar cells are only about 30% efficient, so the total solar energy is about 3 times what they collect.

    I’m sure all you LA natives learned in school that LA County has 4752 square miles, which is obviously ~3M acres. A little multiplication shows that about 1.4 x 10^16 joules of solar energy hits LA County in an hour.

    Mentioned in the article is the simple conversion of a megaton of TNT to 4,184,000,000,000,000 joules. Of course, a Station Fire sized H-Bomb is 3 times that size, or 1.3 x 10^16 joules.

    So given the very fuzzy estimates of a number of the multipliers here, I think it about right to say that one H-Bomb shines down on LA per hour of daylight.

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