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[Note: In light of the enormity of the firestorms happening in Southern California, we are reposting James’ Firestorms for those who missed it previously, or who have something more or new to say. And we send our very best wishes to those suffering from and fleeing from the flames.
-Oaktown Girl, Minister of Justice, WAAGNFNP]

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.

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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.
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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.
Continue Reading »

Sixty-two years ago today, American army units, supported by naval artillery, were preparing for yet another assault on Kakazu Ridge, a part of the outer line of the “Shuri” defenses on the southern part of Okinawa Island. April 1st, Easter Sunday, had been L Day (the landings on Okinawa itself) for Operation ICEBERG. There had been little opposition to the American landings, nor any significant fighting during the first few days of the operation. However, within the first week, American Army units, including my father’s, had begun to run up against the well-established Japanese defenses concentrated in the southern third of the island and which took full advantage of the abundant rocky hills, caves and burial tombs. These engagements marked the start of more than two months of  bitter fighting as American Army and Marine units slowly forged advances through the well-prepared Japanese defenses. When they reached the southern tip of the island in June, the last land battle of World War II came to a close. The Americans had suffered 12,000 dead and 50,000 wounded, the Japanese Army almost 100,000 dead and 7,000 captured (up to a quarter of the army was Okinawan conscripts), and estimates of the death toll among Okinawan civilians ranged from 40,000 to 150,000 (modern consensus favors the higher estimates.)

Hill that was part of the defenses, normally covered with verdant foliage.

US Tanks and infantry on Okinawa.

The campaign for Okinawa had many noteworthy features, including the most intense Kamikaze attacks of the war against the supporting US fleet, extensive use of flamethrowers against entrenched Japanese defenses, mass civilian suicides, the deaths of the commanding officers on both sides - and of the famous war correspondent Ernie Pyle, the sinking of the “super” battleship Yamato, intense disagreements on strategy and tactics within both the American and Japanese commands, and of course the question of what impact, if any, it had on the subsequent decision by the United States to use atomic weapons against mainland Japan. For further reading, I recommend the official Army history available online here, and the books: Operation Iceberg (primarily an oral history) and Tennozan: The Battle of Okinawa and the Atomic Bomb. For me, Okinawa has served as a nexus of the personal and the historical, linking my quest to connect to my father’s specific experiences, with the larger narratives of World War II, war in general and the decision to use atomic weapons . (I want to thank The Constructivist for this post at Mostly Harmless and a subsequent one here at waagnfnp which prompted my latest reexamination of my views on the entire episode, and which led directly to this post.)

As far back as I can remember, I was aware that my father had served in World War II, but it was only after he had rebuked me in uncharacteristically angry tones for suggesting that a particularly intense fireworks display might be akin to an actual bombardment, that I began to view his time in the war in anything other than the most simple-minded comic book terms.
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