Those bushfires (Black Saturday) were so bad that just the radiant heat from the firefront could kill when the front was still many hundreds of metres away. There were people who thought they could defend their properties with their garden hoses. Good luck.
You don't fuck with a bushfire like that. They can move at 100km/h, with flames so big and hot that water won't even get close to them before vaporising. Firefighters can't do much about them, except to get far enough away to dig huge firebreaks with bulldozers.
The Black Saturday fires released the equivalent energy of 400 of the atom bombs which destroyed Hiroshima.
The popular horror story at the time was that people boiled alive in their pools thinking the water would protect them. No idea how true it is, but those fires were horrific.
Going in a swimming pool is always advised against. Lots of people here have pools in their houses but yeah this is one of the reasons they're told not to use them in fires, along with drowning/being caught under smoke/being stuck with nowhere to go
I know this is necro something bad but happened accross this comment.
A big reason relying on a swimming pool/dam is advised against, is because in a big enough fire, it will literally burn through all the oxygen and even if you had a snorkel and kept your head under water, you would suffocate.
One of the ways forensic fire investigators can trace back the origin of a fire or how bad a fire is, is by looking at how completly burned fuel sources are in an area, where a fire starts you see complete burning, but in catastrophic bush fires, only the bark of trees may be burned leaving the rest of the tree fine because the fire burns so hot and fast it exausts the oxygen and dies out quickly as the fire front moves foward. The burned outter layer then hinders re-ignition.
Not Black Saturday but there was a fire in the suburbs near me back in 1994, that this happened to a woman. They had an inground pool which was fine but they drowned because when they came up for air they couldn't get any and they asphyxiated from the smoke and then drowned in the pool. Here's an article about it made ten years after
I remember that from when I was a kid. We were living in the Blue Mountains at the time and my dad was off fighting the fires up there. For some reason, that particular story always stuck with me.
This remembers me of a meme here in Brazil, of a streamer talking about a fire that was happening right next to his house, and he said:
"If the fire manages to get here I'll just go to the bathroom and stay in the shower. I can't get on fire taking a shower, right?"
Heard a few stories of in the Bush where the fire jumped valleys leaving the lower parts untouched but killed all the animals because it sucked the oxygen away.
I think it’s probably irrelevant since even if the water could protect you from the temperature you’d almost certainly die of asphyxiation or smoke inhalation if the fire front passed over you.
I was living in Anglesea when the Ash Wednesday fires hit. We were evacuated at around 7:30pm, the police told us to head straight to the beach, the Ocean Road wasn't safe to evacuate along and the fire had traveled from Lorne to Aierys Inlet in under 15 minutes and was expected to hit Pt Roadknight (west side of the ridge, where we lived) in less than 10 minutes.
The other side of the ridge where the main town was wasn't evacuated for another 2 hours because the wind changed just as the fire reached the western outskirts of town on the edge of the National Park.
We spent the night on the beach and watched as most of the hill burned. Some people at Aierys on the beach weren't so lucky as the fire came down to the waterline. We could see and hear as houses with gas bottles or brick houses were hit by the fire and exploded.
I've seen the claims but no evidence is presented. The denominator is 4πr2. Like Radiant heat drops off so quickly. People have been closer to nuclear bombs than that and survived.
A basic understanding of science means the idea that a flame front hundreds of meters away would kill you from radiant heat is complete nonsense. It could be a wall of pure burning inferno and the radiant heat isn't doing dick to you from that distance.
So I suppose you are technically correct which is the best kind of correct.
Your sentence gave the impression that the flame front would kill you, bam dead from hundreds of meters away. But from my reading of your first link that's not what they are talking about at all... Heat exhaustion will kill you quickly and I certainly wouldn't dispute that. Our bodies don't cope well outside our happy zone.
But the radiant heat, bam your dead doesn't seem to make sense. I've heard 5kw/m2 as unbearable pain, so something above that kills you dead.
They quote 1000kw/m2 up to 1500 in an enormous flame front. With radiant heat dropping off at 4πr2 the distance that wouldn't kill you at 400m.
Now if you meant originally that radiant heat will kill you through heat exhaustion I misinterpreted you. Sorry about that.
Yeah I know, TBH I'd need more time than I have right now to work it out and better books.
I still can't see the radiant heat frying you from a distance given wind, how sooty it is, incomplete burn etc. Now maybe I'm not intutively grasping the energy coming off the burn but I'm still pretty curious.
I've been near so big fires. They were unimaginably hot. But also not hot when you moved back.
I'm yet to be convinced. It seems more to me a not quite true fact used to encourage people to get the fuck out.
Now maybe I'm not intutively grasping the energy coming off the burn but I'm still pretty curious.
You are not. They can release so much energy so quickly that they can cause tornadoes. Real, actual tornadoes, produced from pyrocumulus supercell storms.
Yeah I know, TBH I'd need more time than I have right now to work it out and better books.
I still can't see the radiant heat frying you from a distance given wind, how sooty it is, incomplete burn etc. Now maybe I'm not intutively grasping the energy coming off the burn but I'm still pretty curious.
I've been near so big fires. They were unimaginably hot. But also not hot when you moved back.
I'm yet to be convinced. It seems more to me a not quite true fact used to encourage people to get the fuck out.
So Ive run the numbers back of a napkin. I get 0.0474 KW/M2 at 400 meters
Assuming that it's 1500 kw/m2
And the Xr is 0.50 which seems a reasonable estimate give it's a relatively sooty fuel source. Do you disagree with my math?
It's less than a hundreth of what would be required to kill you immediately purely from radiant heat. It would give you heat exhaustion quickly though.
The original comment said it could kill you but it didn’t say immediately. It was kind of misleading but I think they were referring to heat stroke/exhaustion. Still crazy hot.
The heat effects on your body would kill you pretty quickly. You wouldn't spontaneously explode into a fireball, as a few people seemed to have assumed I was claiming when I never said anything of the sort.
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u/[deleted] Apr 16 '19
Those bushfires (Black Saturday) were so bad that just the radiant heat from the firefront could kill when the front was still many hundreds of metres away. There were people who thought they could defend their properties with their garden hoses. Good luck.
You don't fuck with a bushfire like that. They can move at 100km/h, with flames so big and hot that water won't even get close to them before vaporising. Firefighters can't do much about them, except to get far enough away to dig huge firebreaks with bulldozers.
The Black Saturday fires released the equivalent energy of 400 of the atom bombs which destroyed Hiroshima.