12-31-2019, 12:48 PM
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#8061 (permalink)
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https://www.theguardian.com/australi...tastrophic-day
https://www.npr.org/2019/11/08/77764...umber-of-fires
https://www.theguardian.com/australi...nds-fuel-blaze
Entire towns evacuated, about 4,000 people forced to escape the fire on the beach, fire tornadoes - strong enough to lift a 10 Ton fire truck and flip it onto its roof, killing the volunteer firefighter in it.
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12-31-2019, 01:22 PM
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#8062 (permalink)
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Human Environmentalist
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I would expect declining O2 concentrations to curtail fire more than fractions of a degree increase in temperature would encourage them.
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12-31-2019, 02:35 PM
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#8063 (permalink)
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Master EcoWalker
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Quote:
Originally Posted by redpoint5
I would expect declining O2 concentrations to curtail fire more than fractions of a degree increase in temperature would encourage them.
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O₂ concentration would fall with the rise of C0₂ concentration, I guess that's what you expect?
Well, CO₂ is at 415 ppm currently, up from 200 before mankind.
O₂ is at about 210,000 ppm. Maybe that was 210,215 ppm back then. It is less now... about 0.1 %, or 0.02% of the whole atmospheric content.
Fire is a chemical reaction triggered by heat. More heat, more fire. Even at 0.02% less oxygen.
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12-31-2019, 02:56 PM
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#8064 (permalink)
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Perhaps.
Fire requires fuel, heat, and oxygen. For every Carbon atom it binds 2 Oxygen atoms. Not only is it removing free O2 to reduce its concentration, but also diluting it with inert CO2.
If temperatures have risen a degree, then going from 300 Kelvin to 301 represents an increase in temperature of 0.3%
I know from much experience building fires that they generate their own heat, and the best way to promote the fire is to increase oxygen, which is why we blow on the fire when it's going out and not build a greenhouse around it.
I'm willing to be wrong though.
Last edited by redpoint5; 12-31-2019 at 03:11 PM..
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12-31-2019, 04:16 PM
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#8065 (permalink)
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Chemistry does not step in line with a % increase on the Kelvin scale.
See https://www.chemguide.co.uk/physical...mperature.html
Quote:
As you increase the temperature the rate of reaction increases. As a rough approximation, for many reactions happening at around room temperature, the rate of reaction doubles for every 10°C rise in temperature.
You have to be careful not to take this too literally. It doesn't apply to all reactions. Even where it is approximately true, it may be that the rate doubles every 9°C or 11°C or whatever. The number of degrees needed to double the rate will also change gradually as the temperature increases.
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Mind you, fire starts when a tipping point is passed. Even a small increase in reaction speed can make the difference for a lot of potential fires. A 10% increase in reaction speed, which a 2 degree Celsius increase in temperature would amount to, will have a big effect.
As for CO₂ being inert, so is nitrogen which makes up 79% of the air. The 0.02% increase in inert gases the extra CO₂ stands for is insignificant, unlike its effect on acidity and heat radiation shielding.
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12-31-2019, 07:07 PM
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#8066 (permalink)
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Nitrogen is not inert.
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12-31-2019, 07:23 PM
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#8067 (permalink)
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Quote:
Originally Posted by Grant-53
Nitrogen is not inert.
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I meant non-combustible, and RD understood that.
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12-31-2019, 08:28 PM
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#8068 (permalink)
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Quote:
Entire towns evacuated, about 4,000 people forced to escape the fire on the beach, fire tornadoes - strong enough to lift a 10 Ton fire truck and flip it onto its roof, killing the volunteer firefighter in it.
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Everything in Oz-tralia tries to kill you. Even the fire trucks!
Quote:
Mind you, fire starts when a tipping point is passed.
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Hence the term conflagration.
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12-31-2019, 11:37 PM
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#8069 (permalink)
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Last edited by freebeard; 12-31-2019 at 11:43 PM..
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01-01-2020, 12:09 AM
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#8070 (permalink)
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In new Mexico the only thing that really bugs me is the locust plague.
Don't read about photon duality before bed.
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