GNF & World War II & Apocalypse & Science & WAAGNFNP Posted by James Killus, 13 Aug 2007 06:49 am
Firestorms
If you try to light a match under micro-gravity conditions (we all got used to “zero-g” so some smarty pants had to go and call it “micro-gravity”) and just hold it in one place, it will self-extinguish. The match will use up enough of the oxygen in its surrounding volume of air to extinguish the flame. It doesn’t have to use up all the oxygen, either; most flames go out in air that still has enough O2 in it for people to breathe—barely.
Depending on the fuel, (e.g. hydrogen needs less oxygen to burn than methane does), the usual figure given is that 14%-16% oxygen is needed to sustain a fire. People can manage on a bit less; Biosphere II dropped below 14% before they pumped in some additional O2, but they didn’t have to contend with elevated CO2 levels; in fact, what they’d been losing was CO2, by absorption into their nice new concrete structure, with bacteria converting soil organics and O2 into CO2. They’d had a bit of a “slow burn.”
Your basic candle flame is fed fresh air by gravity, specifically, the air coming in to replace the hot gases that have become lighter than air in the hot flame. That’s called the “fire draft” and fireplaces exist to direct the fire draft upwards, so the smoke doesn’t choke the people warming themselves by the fire. The chimney/flue of the fireplace also accelerates the fire draft if you build it right, and both Ben Franklin and Benjamin Thompson, (Count Rumford), invented some tricks that are still in use.
So fires always produce an updraft. In truly big fires, the question becomes how the updraft interacts with the local weather. If the local winds are stronger than the updraft, and the fire is big, uncontrolled, and uncontained, you have a conflagration. If the fire creates its own winds, you have a firestorm.
Neither is anything you or I want to be near. A running wildfire can exceed 70 mile per hour under upslope flow conditions, where the fire draft adds to the natural winds. Firestorms generate their own weather, their own winds, and can create small tornadoes, “dust devils” made out of flaming gases that light everything they touch.
The heat in the interior of a firestorm pyrolizes everything within its boundaries, but the fuel produced exceeds the air available. So the hot mass rises as a fireball, sucking more air into it, maintaining its heat even as it expands, because there is still plenty of fuel gas left to burn. A firestorm spreads as much by thermal radiation as by flaming contact, sometimes triggering fires at a distance, like across a valley.
Kurt Vonnegut lived through the firebombing of Dresden, and wrote about it, so more people know about the 35,000 people who died there than in Operation Gomorrah, which killed a larger number (50,000 est.) in Hamburg, or the 120,000 who died in the Tokyo fire raids. I’d never even heard of the raids on Kassel, Braunschweig, Darmstadt, Heilbronn, Pforzheim, and Würzburg until I looked them up for this essay.
But fires are tricky to set with conventional incendiaries. Most of the WWII fire raids were duds, or semi-duds, producing some fires, but nothing like a real firestorm. There were four attempts on Hamburg before they hit the jackpot.
But Hiroshima was a jackpot; what the first blast didn’t do, the subsequent firestorm did, and 4 square miles of the city just went away, nothing left, not even steel, much less teeth and bones.
The Nagasaki bomb was bigger, but the targeting wasn’t as good, and the city had the good fortune of having a lot of hills, which shielded some from the blast, the heat, the radiation. Moreover, the hills altered the wind field, and the resulting fires are only classed as a conflagration. Still, 40,000 people died quick, and maybe four times that number died slow, from injuries, from radiation, from the long term illnesses that go with radiation, from trauma, and grief.
In 1944, the most powerful bomb used in warfare was the British Grand Slam on the order of 10 tons of TNT, although the U.S. developed (but never used) one that was twice as big. In 1945, of course, nuclear weapons increased bomb yields by three orders of magnitude.
It’s hard to develop a sense of scale once you start dealing in factors of a thousand. People think “nuke” and think “Hiroshima and Nagasaki.” But those bombs were measured in kilotons.
Thermonuclear weapons are measured in megatons, another factor of a thousand, so we got a factor of one million increase in about half a decade. Go look for pictures of atmospheric bomb tests. See that one near the mountain? You can see the billows in the clouds and dust that it shakes up the near field.
That’s a bomb that’s in the kiloton range. There have been industrial accidents that can be measured in kilotons, like the Pacific Engineering Company plant in Henderson, Nevada, where over a thousand tons of ammonium perchlorate blew up. That was a kiloton explosion.
Now go find some photos of the Pacific island H-Bomb tests. Google on “Castle Bravo” for example, the biggest miscalculation in the history of nuclear weapons. It was supposed to produce 6 megatons; instead they got 15. “Castle Romeo” was part of the same mistake. They expected 4, but got 11.
See those shapes in the sky above the mushroom cloud? That’s the stratosphere.
The thermal radiation effects of nuclear devices loom larger as the energy release increases. In Hiroshima, the firestorm was likely caused by the blast itself, in the same way that an earthquake causes fires, by turning building into kindling, by releasing natural gas, by rupturing fuel tanks. The heat from the bomb itself probably lit only a few of the fires.
But megaton blasts, perhaps over grasslands, forests, farms? The experiment has yet to be preformed. And calculations, simulations, and estimates are so very, very unsatisfying, aren’t they?
Trackbacks
Responses to “Firestorms”
-
on 13 Aug 2007 at 9:02 am 1. JP Stormcrow said …
I must admit that I was surprised by your Dresden toll, but googled around and see that it is in line with the thinking of current historians. It appears that it was more than just Vonnegut’s eyewitness account that magnified Dresden in the popular imagination, Goebbels started the ball rolling, and the faux historian David Irving wrote a book which also promulgated the higher numbers.
All that said, the focus on the specific count of the dead (which I am indulging in here) is a rather grim calculus and somewhat irrelevant to the larger point.
-
on 13 Aug 2007 at 11:02 am 2. James Killus said …
The realm of statistical and hypothetical dead is rather a grim calculus, isn’t it? And it can produce such bizarre paradoxes. If one estimate of the Dresden deaths is 250,000 and we decide that it was really 35,000, then 215,000 hypothetical people have miraculously returned from the dead. But others then say, no, no! the larger number even was an underestimate, and hypothetical people tremble, as their fates hang in the balance. Dead or alive? Does it matter when you’re only hypothetical? Do the error bounds of statistics render some of those poor souls only half alive? Can one be two sigmas from death? Or eventually is everyone crushed when the mixed waveform collapses and Shroedinger’s Cat claws our throats until the blood spurts in a Newtonian arc?
-
on 13 Aug 2007 at 1:49 pm 3. Seattle said …
Before we got into the question of hypothetical deaths, this post reminded me of “Independence Day” (the film). Ways in which a little knowledge can ruin a perfectly good action bit in a flick: I have a soft spot in my heart for “Independence Day”. I actually saw it on July 4th the year it came out and I still remember the smell of the street person sitting near me as I watched it…but that’s another story. So I’m sitting there watching the scene where Will Smith’s love interest is trying to escape LA with her little boy and dog and they are stuck in traffic in a tunnel. The aliens have fired their “primary weapon” and she can see the firestorm coming in the rear view mirror, right beside the face of her little boy in the back scene. So she’s hauling ass to get out of the car and get the boy out and it’s one of those scenes that pulled all my parental heartstrings because I know she can’t make it. She’s trapped. So she kicks in a utility door in the tunnel at the last moment and mom, boy, and dog are all saved…but I’m thinking, “NO WAY!” Even if they didn’t get burned, they’d suffocate because those fires suck all the available oxygen into them. Gets me everytime I watch my copy of it.
-
on 13 Aug 2007 at 1:52 pm 4. Seattle said …
Yes, I have a copy-on video.
-
on 13 Aug 2007 at 1:53 pm 5. JP Stormcrow said …
Chris Clarke has a nice piece of writing up at his place today visualizing the effect of a volcanic event in California during the Miocene on nearby wildlife (much more direct than the ashfall I mentioned yesterday.). One of the commenters then links to this stunning picture of wildlife at a forest fire in Montana.
The image was captured in the late afternoon of Sunday, August 6 from a bridge over the East Fork of the Bitterroot River just north of Sula, Montana. …several forest fires converged near Sula into a firestorm that overran 100,000 acres… Temperatures in the flame front were estimated at more than 800 degrees.
-
on 13 Aug 2007 at 2:05 pm 6. Seattle said …
Bark Beetles on the grill….
-
on 13 Aug 2007 at 2:28 pm 7. JP Stormcrow said …
Re: Seattle in #3 - escaping the firestorm in Independence Day
This reminded me of a thread at MB’s place on movie cliches. One person used “Steven Seagal outruns physics” for the usual fire outrunning. I guess in this case they knew that was too bogus and hackneyed and went with a new variant.
But nothing bogus in that movie could compete in my mind with the software virus infecting the alien ships. It recalled E.E. “Doc” Smith in his glory.
-
on 13 Aug 2007 at 2:43 pm 8. James Killus said …
You’re all being kinder to the scene in Independence Day than I was.
A firestorm doesn’t move outward at its base; the winds converge. What is shown in Independence Day is the other Hollywood trope of “outrunning a shock wave.” You can also see this in Chain Reaction with Keanu Reeves, Die Hard, in the rooftop explosion scene and in pretty much every other movie that substitutes fireballs for explosions and then makes the fireballs move really slowly.
Shock waves are supersonic. People run really fast in Hollywood
-
on 13 Aug 2007 at 3:22 pm 9. Seattle said …
Will Smith (in character): “Can you really do all that bullshit you just said?”
-
on 13 Aug 2007 at 3:35 pm 10. Kiera PSI said …
I used to go to movies with a rocket scientist. Really, he had a PhD in particle astro-physics (or something to that effect). After two miserable attempts to watch a SciFi movie with him, I refused to see any others in his company. He just didn’t get the “suspend your disbelief and enjoy it as entertainment” philosophy that the rest of us lived by.
It wasn’t that we didn’t know that you couldn’t shoot a missle from a Harrier Jet through a building with a man hanging from it and have it go straight and hit a helicopter on the other side (True Lies)…we simply chose to ignore the impossibility of the man’s weight having no apparent effect on the trajectory (let alone not just making it go almost straight down into the near side of the building) and enjoyed watching the terrorist and his buddies get blown to smithereens.
Ignoring that these things aren’t possible is just plain FUN.
-
on 13 Aug 2007 at 3:58 pm 11. Seattle said …
Ah, that would be similar to my experience trying to watch almost any film involving gun shooting with my friend who used to sell guns out of the back of his car.
-
on 13 Aug 2007 at 3:59 pm 12. JP Stormcrow said …
Actually, I think willingness to suspend disbelief in entertainment is one of those hidden things you should check out in any potential life partner. (Another is to watch a Top 100 movie comedies countdown together … this one is really important.) SCiFi and Action flicks are big ones, but it can happen in all genres. my father-in-law saw Never Cry Wolf with us and just hated it - because of a few implausibilities (they were rather egregious, especially a “falling through the ice” scene) - while my wife and I were perfectly willing to put them aside and enjoy it for what it was. It really did cause for strained post-movie conversation.
-
on 13 Aug 2007 at 4:08 pm 13. Seattle said …
Did he hate it worse than the shooting the circle in the ice while falling down 3 stories scene from “The Long Kiss Goodnight”? LOL
-
on 13 Aug 2007 at 4:10 pm 14. Kiera PSI said …
This is one reason (out of several) why the rocket scientist is not part of my life.
While the D-Man and I don’t always agree on what is entertaining (he likes NASCAR, I like Monk and Psych), we care about each other enough to sit and watch the other’s pet shows without (too much) negative comment.
-
on 13 Aug 2007 at 5:44 pm 15. James Killus said …
Ach, I never said I didn’t like Independence Day, just that I’m pretty tired of that particular trope that is used to generate what a friend and I decided to call “boring suspense,” (bs).
The Die Hard scene is an absolute classic, while the Chain Reaction scene just lies there. Others vary, depending upon how much they milk it and how well they’re done.
Then, of course, one can increase one’s enjoyment through properly snarky comments (oh, the much maligned Mystery Science Theater 3000). For example, after Data explained the architecture of the Borg computer hive mind in whatever-the-hell-the-movie-was-named, just before they hit it with (oh, the suspense) a computer virus, another friend said, “Well, thank God the Borg are running Unix.”
Of course if they’d been using Windows, they’d have crashed a long time ago, presumably in a galaxy far, far, away. Clearly, Microsoft, like the common cold, is our best defense against alien invasion.
-
on 13 Aug 2007 at 7:05 pm 16. JP Stormcrow said …
The realm of statistical and hypothetical dead is rather a grim calculus, isn’t it?
Yes, and as a kid studying the World Almanac it raised real questions for me, some of them quite interesting, as I tried to puzzle out the relative “notoriety” of disasters in relation to the number of deaths. An interesting one in ye olde firestorm category is Chicago fire vs. Peshtigo fire. The latter happened at the exact same time as the Chicago one, burnt huge swaths of northern Wisconsin and Michigan and took 1,200 - 2,400 lives (200-300 died in Chicago), yet is very little known. And there are of course “good” reasons for this, it just was a bit hard as a kid to puzzle it out. Another trend that piqued my interest was the huge difference in storm and earthquake casualties in Asia versus the US (and Europe as well.)
-
on 13 Aug 2007 at 9:11 pm 17. Oaktown Girl said …
What a hellacious day at work. Didn’t even have time to make one little stinkin’ comment. (So here I am now at home at 8:55pm).
I know I bring this up every time Independence Day comes up in multiple comments on a thread, and I’ll probably be doing it until I draw my dying breath (which, frankly, can’t come soon enough): Seattle: did you have “The Talk” with your older boy about the 2 main female “significant others” in the movie? The one where you explain the explicitly racist casting of Will Smith’s girlfriend being a stripper while Jeff Goldblum’s lady was a powerful White House cabinet officer (I forget her what her exact title was). A stripper? Not that I look down on strippers, but come on. You got one Black woman in the movie and she’s gotta be a stripper? I don’t know if I can really convey to anyone here who’s not Black (esp. not a Black woman) what that’s like. A lot of us (Black folk) were disappointed in Smith for letting that go down. We felt he had enough clout and influence (and consciousness) at the time to say, “Hey, guys - let’s talk about this. This ain’t right”.
-
on 13 Aug 2007 at 9:15 pm 18. Oaktown Girl said …
But back to the firestorm…
If the local winds are stronger than the updraft, and the fire is big, uncontrolled, and uncontained, you have a conflagration. If the fire creates its own winds, you have a firestorm.
Or, put another way, the level of tension in Oaktown Girl’s house on Thanksgiving Day.
-
on 13 Aug 2007 at 11:01 pm 19. Bill Benzon said …
Um . . . err . . . when they outrun firestorms and such, they’re on ‘roids, right?
Oaktown: You’re right about that stripper-thing. Some real heavy-handed and deep-seated cultural mythologizing going on there. As for Will Smith, did you know that his Fresh Prince buddy, Alonzo Ribeoro once did a “how-to” book (YouTube goodness) on break dance styles?
-
on 14 Aug 2007 at 6:43 am 20. Kiera PSI said …
Re: 17…I don’t really think this was a conscious race stereotype by them. It just so happened that their star was black, so they decided to make his girlfriend black because blacks were way under-represented in the film. They needed to have some reason for him to be kept out of the Space Program that didn’t have anything to do with him or his race, and the publicity nightmare that would ensue if an astronaught was revealed to be marrying a stripper of any skin color is a good one. He had to be shown as all noble and doing the right thing (sticking with his woman) for love, regardless of the consequences to his career. Only then does the irony of him getting into space before any of the ones selected over him become, well, ironic. This would have worked every bit as well if they were both white, or hispanic, or asian. And Jeff’s girlfriend, be she white, hispanic, or asian, had to have access to the President. They could have easily made her non-white, though, since whites were over-represented. Maybe they thought they were already being edgy because she wasn’t Jewish? (Tongue definitely in-cheek for this last sentence).
-
on 14 Aug 2007 at 12:40 pm 21. James Killus said …
Hmm. Interesting that the plot could have been just as easily served if the Will Smith character had had a white girlfriend who was a stripper, and Jeff Goldblum’s girlfriend could have been a black advisor to the President.
It probably wouldn’t have even hurt at the box office, but there’s no way they were going to take that “risk.” People project their own racism onto the audience, and thereby consider themselves superior to that audience.
-
on 14 Aug 2007 at 12:43 pm 22. Kiera PSI said …
What’s interesting is that the stripper with a noble soul and a heart of gold marrying the hero is a tried and true movie plot…mostly from westerns. And in them, both the hero and his slightly tarnished girl were white. That’s why I think the apparent “racism” of this instance was unintentional. The good thing is that they DID make the hero black. Their “crime” is that they didn’t consider what the change in race of the hero and his girl would do to the audience’s perceptions.
-
on 14 Aug 2007 at 1:12 pm 23. Seattle said …
I’ve always thought of “Independence Day” as a guy flick and the female roles fall accordingly in line-regardless of race. Supportive or unsupportive but singularly lacking in technical skills. (No female pilots, no computer skills-and properly reined in on the independence issue.) In the end they all stood by their men and waited in the wings until the aliens were defeated-or died. Pretty classic. Despite(or possibly because of) the strip tease scene, I thought “True Lies” did a better job on the lead female role.
-
on 14 Aug 2007 at 1:38 pm 24. Bill Benzon said …
No particular reason to think the ID-stripper thing was conscious racism. It’s just lazy and routine and, yeah, still racism. That’s what makes it bothersome.
-
on 14 Aug 2007 at 2:19 pm 25. Oaktown Girl said …
That’s why I think the apparent “racism” of this instance was unintentional.
Kiera, it may have been unintentional in that it wasn’t done consciously, but therein lies the rub - that’s exactly where racism usually resides in “civilized” society: in the unconscious. Old habits and thought patterns get repeated over and over. That’s why consciousness and awareness is so important. And those 2 things can only come about by bringing some color (having different perspective to the “table”, as it were) to the places where decisions are actually made.
Seattle - it may be a guy’s flick, but the guys also fall along the same old stereotypical racial lines. White guy is the brainiac (and fairly good looking to boot), while the Black guy is the muscle (macho pilot in this case). That jumped out at me almost as much as the female racial roles did.
-
on 14 Aug 2007 at 2:37 pm 26. Bill Benzon said …
Unconscious racism can be strange. Some years ago I was attending a performance of traditional West African dance. It was in a “world artists” series and this show was obviously intended to attract a black audience. And it did.
I was with a friend who is black (I’m white). And when we approached the nice lady who was taking tickets, she gave us a strange look, but only for a microsecond. When we got inside I asked my friend, “Ade, did she just give us a back-of-the-bus look?” Ade just chuckled and agreed.
The only thing that halfway makes sense is that the nice lady was prepared to see white folks and black folks, but separately. We she saw me and Ade acting like we knew one another, that didn’t compute.
I long ago gave up saying I’m colorblind. I pay minute and particular attention to race. It’s the only way I can keep straight on it.
And it’s a drag.
-
on 14 Aug 2007 at 10:47 pm 27. Oaktown Girl said …
By the way, one of the reasons I liked this post is because of the the way you explained it, I actually understood most of science you were talking about. So thanks for that.
Speaking of Mystery Science Theatre (which somebody was somewhere up there), I’ve always fantasized about me and 2 of my girlfriends being able to do commentary like the 3 male figures do. Not just on MST-style movies, but on all sorts of movies. It would have to be Pay Per View, of course, because the commentary would include “adult” language. But that’d be so great. People need to hear more non-sellout female commentary, not this watered-down bullcrap like “The View”, whose only saving grace was Rosie, (sometimes), so she had to get run-off for not being a full-time patriarchal ass-kissing military industrial complex tool 100% of the time. But don’t get me started.
-
on 15 Aug 2007 at 5:12 am 28. christian h. said …
Racial and gender stereotypes in Independence Day? That movie is a walking stereotype. Not only is the brainy guy white he’s…. wait for it… Jewish American. WTF? And then we have the always-drunk, white-trash, Vietnam vet. And the presnit is a fucking hero for flying a fighter plane in the previous Gulf War (I’ve given up counting them). A hero? What’s heroic about bombing people who don’t shoot back?
That movie at the time reinforced every single anti-American stereotype everyone I knew in Germany (including me) had. The irony being it’s made by a German.
Mars Attacks came out the same year - I enjoyed it so much better. -
on 15 Aug 2007 at 5:23 am 29. christian h. said …
As for firestorms: my father was a kid during WWII. After one of the big attacks on Kassel happened, he and his fellow grade schoolers - living in a village near Goettingen, not quite 50km away - were sent out into the fields to collect the parts of the Kassel state records archives that had been carried there by the updraft. Heavy books recording everything from deeds to birth certificates. Blown 50km away from the archives, which had sustained a direct hit, raining down in the farmer’s fields.
-
on 15 Aug 2007 at 9:24 am 30. James Killus said …
christian h.,
Okay, that’s impressive.
Next up: rain of precooked frogs.
-
on 16 Aug 2007 at 12:22 am 31. Spyke said …
“Did he hate it worse than the shooting the circle in the ice while falling down 3 stories scene from “The Long Kiss Goodnight”? LOL”
There were so many things in that movie that just couldn’t work - Samuel L. Jackson getting blown out of the building while strapped to a chair, immediately comes to mind.
But damn, TLKG is a blast to watch!
I love that movie. -
on 16 Aug 2007 at 10:12 am 32. James Killus said …
I have a theory that at least some of the egregious errors in movie stunts are due to the ongoing “comicbookification” of motion pictures. One the one hand you have more and more movies based on comic books For example, the comic company Dark Horse has sale of movie rights, and its inverse, the making of movie-based comics, as a major part of its business model.
On the other hand, CGI special effects removed the need for any connection to physical reality–just like comics.
Comic book characters routinely survive events that would be fatal (and look faked) in any live action sequence. But as time goes on, people get more and more inured to live action sequences that push that envelope.
-
on 16 Aug 2007 at 10:14 am 33. Oaktown Girl said …
Spyke and Seattle - you know, I’ve never seen Long Kiss Goodnight, though I’ve heard of it, of course. Looks like a fun movie, you know, if you can see if for free (or for no more than you’re already paying in cable TV fees).
We need a movie with a shock wave cutting a hole through ice to let the heroes escape. Of course, part of the fantasy would have to be that there’s still enough ice left anywhere to do that.
Beautiful and majestic Springfield Glacier
