Is it theoretically possible to make the atmosphere flammable? Through pressure or converting/isolating certain elements of the atmosphere’s chemical makeup? Is it possible on a small scale? On a large scale?
When the first atom bomb was tested a few people were worried it would ignite the atmosphere. Most people at Los Alamos didn’t think it would happen so the test went ahead.
That was a worry about a nuclear chain reaction, not a chemical one like the OP is talking about.
As for the OP; the atmosphere is almost all nitrogen and oxygen. On a large scale, I doubt there’s enough fuel to ignite the atmosphere, even if you magically separated all the CO2 & water into carbon, hydrogen and oxygen. On a small scale, I’m sure with enough processing you could concentrate and reformulate the atmosphere so it would burn. Or make diamonds out of it for that matter.
It could if fuel was added, but oxygen and nitrogen, which is the vast majority of the atmosphere require energy input to combine. As for a nuclear reaction, fusion becomes endothermic at iron or heavier, so at some point of extreme temps and pressures it should be possible, like throwing the earth into a star hotter then the sun.
The free oxygen can certainly combine with something flammable. happens all the time everywhere there’s a fire, whether natural, man made, or inside any engine. (except a rocket, you nitpickers).
If, say, methane were to start pouring from a crack in the ground in truly immense proportions, eventually somehow it’d ignite. And then you’d have a sustaining fire there until the methane stopped flowing.
You couldn’t get from the current atmospheric composition to one which was uniformly flammable without passing through local concentrations that would tend to catch fire & burn, reducing the fuel supply.
bottom line: Armed with a magic wand, you could create a planet with a uniformly flammable atmosophere. And then set it off. But any real planet would have localized fires consuming the fuel & oxygen long before they got to a planetary-scale stoichiometric mixture.
One normally thinks of this happening in confined settings such as homes with gas leaks, but pretty much precisely the open air scenario that LSLGuy describes occurred in Russia in 1989.
There are trace amounts of methane and other hydrocarbons in the atmosphere. Methane in the atmosphere is about 1700 parts per billion, or 1.7 ppm (http://www.epa.gov/methane/scientific.html). The lower explosive limit for methane is 5%, or 50,000 ppm (at STP, and otherwise ambient atmosphere). So if you could concentrate the methane in the atmosphere by a factor of 29,000, you could ignite it. If you can also concentrate oxygen at the same time, so you end up with just oxygen and methane, you could probably get by with slightly less methane, at a wild guess something like a concentration of 10,000 or 5,000 times.
So, if you think picking the one part per million of methane out of the air and then lighting it on fire counts as burning the atmosphere, then the answer is yes. Otherwise, no.
If Man Disturbing The Balance Of Nature™ could somehow destabilise all the methane clathrates on the planet leading to the release of all their gas, would this get the atmospheric methane level up to the right concentration?
Because if so one could have a truly awesome doomsday scenario whereby The Hubris of Humanity (R) results in the ignition of the atmosphere, which would not only incinerate us all, but transform the atmosphere into a suffocating mixture of N2 and CO2, which might then result in a permanent runaway greenhouse effect turning the earth into a sterile pressure cooker a la Venus.
I make that potentially 4 Armageddons for the price of 1 if the initial outgassing event was reasonably catastrophic, with bonus points for Destroying Not Only Ourselves But All Life As We Know It ™(R)(C)
Into Deepest Space by Fred Hoyle and Geoffrey Hoyle had a somewhat similar scenario, where hostile aliens planned to fill Earth’s atmosphere with hydrogen until it ignited and killed everything.
This is only one of the reasons that the movie Battlefield Earth was a pile of utter shite.
It didn’t even have to ignite in the classic, flaming sense, merely drift in and sequester oxygen into water, molecule by molecule.
Let me guess: The hydrogen just spontaneously came into existence, one atom here and there?