I would guess the simple answer to to both is no, although not so sure about 2.
the temperature shouldn't make a difference as long as it doesn't deprive the fire of fuel & oxygen. Both will keep the fire going & generate heat irrespective of the surrounding temp. For this reason I would suggest that it would have no effect on the rate of consumption as it will remain hot, again irrespective of the surrounding temp.
this is just my educated guess as a scientist without actually researching the matter
I would venture to say that the answer to both questions is probably yes.
For example, you must raise the temperature of paper to 451 F in order for it to burn, to use a famous example. If the ambient temperature drops enough, such that 451 F is not maintainable, the fire would have to go out. (Although oxidation might continue, at a much slower rate.)
We are just so accustomed to working within a narrow range of temperatures, say 0-40 C, that the phenomena that occur at much lower or much higher temperatures are not intuitive.
Originally posted by elfuente: I would venture to say that the answer to both questions is probably yes.
For example, you must raise the temperature of paper to 451 F in order for it to burn, to use a famous example. If the ambient temperature drops enough, such that 451 F is not maintainable, the fire would have to go out. (Although oxidation might continue, at a much slower rate.)
We are just so accustomed to working within a narrow range of temperatures, say 0-40 C, that the phenomena that occur at much lower or much higher temperatures are not intuitive.
see what you are saying elf' and I may be splitting hairs here but the question was specifically refering to the air temperature not the substance burning, nor was paper mentioned. I still maintain that the surrounding air temperature wouldn't necessarily affect the substance burning, I think
I would also argue that, if the answer to 1 was yes and a dramatic drop in ambient air temperature would cause a fire to go out then surely the answer to 2 would have to be no, as the drop in ambient air temperature has put the fire out i.e. a dramatic drop in ambient air temperature has ceased the rate at which a fire will consume its fuel.
I was thinking about a much lower temperature drop, say -100 or -200 C.
And of course it would depend on the substance being burned. If it was large pieces of wood, even a precipitous fall in ambient temp would have a difficult time lowering the temp immediately surrounding the burning wood, or at least it would take a while.
And then of course some substances, like rocket fuel, are so flammable that no temperature is too low, given an ignition source that can get hot enough to start the reaction.
So, I think the answers to these questions require specification of the fuel (paper, wood, etc) and the starting and ending temperature. We would have to look up the energy of activation for each exothermic reaction.
I enjoyed that movie, but it is definitely not a sci-fi classic. One viewing was enough.
Some of the ice cores drilled in Greenland, however, do suggest that in some ice ages in the past, the big glaciers reached some pretty low latitudes in just a few years, like maybe 10.
Of course it will be necessary to blame somebody. I'm torn between Boy George and George Bush.
I enjoyed the film, however exagerated, till the end. His father risks his life trekking accross the frozen wilderness then when he gets there calls the helicoptors to rescue them. why not just go there by helicoptor in the first place or did I miss something?
Henyway.. to make my question a bit more clear cut...
If you were to light a fire in Death Valley (+40 degrees) and at the south Pole (-40 degrees), each fire had exactly the same type and amount of fuel (logs)and there was no wind or precipitation to "influence" the fire in any way, would there be any diffrence in the rate that the fire burned its fuel - would one fire burn "quicker" than the other???
Originally posted by Greenjack: I enjoyed the film, however exagerated, till the end. His father risks his life trekking accross the frozen wilderness then when he gets there calls the helicoptors to rescue them. why not just go there by helicoptor in the first place or did I miss something?
Originally posted by Amber Nectar: Henyway.. to make my question a bit more clear cut...
If you were to light a fire in Death Valley (+40 degrees) and at the south Pole (-40 degrees), each fire had exactly the same type and amount of fuel (logs)and there was no wind or precipitation to "influence" the fire in any way, would there be any diffrence in the rate that the fire burned its fuel - would one fire burn "quicker" than the other???
I guess the only thing that might affect the rate at which the fuel burns would be if the change in temperature had an effect on the amount of oxygen present.??
Originally posted by Amber Nectar: Henyway.. to make my question a bit more clear cut...
If you were to light a fire in Death Valley (+40 degrees) and at the south Pole (-40 degrees), each fire had exactly the same type and amount of fuel (logs)and there was no wind or precipitation to "influence" the fire in any way, would there be any diffrence in the rate that the fire burned its fuel - would one fire burn "quicker" than the other???
I guess the only thing that might affect the rate at which the fuel burns would be if the change in temperature had an effect on the amount of oxygen present.??
would it be correct to assume that at the poles, where the air is colder, that the oxygen molecules in the air would be closer together?
I don't know if this would have any affect on the burning fire though
Originally posted by Amber Nectar: would it be correct to assume that at the poles, where the air is colder, that the oxygen molecules in the air would be closer together?
They would be less energetic though such minor difference in Temp is negligible. The air temp could affect a fire. A fire requires three things; Fuel (the material to burn), Oxygen and Heat. Obviously the temp affects the fuel but as others have mentioned this would have to be a low temp to cause a fire to be extinguished or unable to be made. Remember though that if you apply a flame to a frozen item (the fuel) then you would effectively raise the local temp of the fuel to its burning point (eventually).
Actually many mil vehicles used in Arctic and sub Arctic conditions are often fitted with a device which causes an small explosion to "kick start" the engine as the normal ignition system is unable to cope with the extreme cold which can be encountered. But even then we are talking about real extremes, not the norm.
A fire is a chemical reaction. In the most common examples it is equal to the word "oxidation". The fuel molecules are combining with oxygen, and heat is produced.
Every chemical reaction has a specific energy of activation. Usually this can be thought of as the temperature which must be reached before the reaction can start. Again the famous example from Ray Bradbury; for burning paper it is 451 degrees F.
So as long as you have an ignition source that can bring the paper to that temperature, a fire will start. And as long as the fire, once started, is able to maintain that temperature, the fire will continue. Both of these become more difficult as the temperature reaches extrememly low levels, but given no wind, a match should be able to start a paper fire at an ambient temp of -50C as well as it does at +25C. And at -50C the oxygen atoms would be closer together as the air is more dense, but as Joob explained, they would also be moving more slowly which would offset any advantage gained in higher density.
You see heat is nothing more than a measure of how fast atoms and molecules are moving. At absolute zero (-273C, or 0 degrees Kelvin) all motion stops. There is no known upper limit.
A word of practical advice: If you're going hiking where the air is extremely cold, carry a lighter that forces a butane flame under pressure from the ignition chamber. These are usually called "wind-proof" lighters. In fact carry at least one back-up lighter and extra fuel and you should be fine. Just remember that flesh freezes almost instantly below -50C, so a urination break is not exactly a casual thing.
I've read that what the Inuit and other far north people do is make a little tent-like thing and do it in there.
To recommend a novel, there is one called "Smilla's Sense of Snow" by a Danish writer whose name I can't recall right now. It's a mystery/detective kind of story, some of which occurs in Greenland and on the polar ice. It was also made into a very nice movie by the same title.
I think that modern polar explorers carry a bag inside their clothes for the purpose.
Of course when the ice caps melt all of this may not be necessary any longer.
