What would it take to ignite the atmosphere?

[Noisy Rhysling]

The Los Alamos guys were laying bets on what would happen when the Trinity device went off. This ranged from "wet firecracker" to "igniting the atmosphere". (I've read ahead, it was something in between.)

My question is, would it be possible to build an atomic bomb that could actually "ignite the atmosphere", or have we learned that such a device is essentially impossible?

(Move ok, mods.)

 

[DaveC426913]

The atmosphere is not a fuel, nor does it contain much in the way of fuel except traces.

It contains oxygen, which allows other things to burn (rather vigorously) but there's nothing in the atmo that can burn (that hasn't already been burned by being oxidized.)

 

[fresh_42]

Around 800°C nitrogen oxidizes, which could be called burning. This happens in many ways today on small areas, e.g. in our motor engines. For the atmosphere to burn, we'll have to wait another few billion years, but I'm not sure when exactly the sun will be red enough.

 

[Noisy Rhysling]

Well, that's that then.

I did read a story when I was in high school about a rocket that used "catalytic iron"* for fuel and it set off the iron on the surface of the Earth.

*I had to Paper Google "catalytic".

 

[DrStupid]

My question is, would it be possible to build an atomic bomb that could actually "ignite the atmosphere", or have we learned that such a device is essentially impossible?

Due to the low density, the temperature would need to be much higher compared to the conditions of the corresponding processes in large stars (e.g.the oxygen-burning process). And I'm not even talking about a thermonuclear chain reaction. Even if ignition is possible, I would expect that the process stops almost immediately.

 

[mfb]

@DaveC426913 and @fresh_42: The question is about nuclear reactions.
The reaction of nitrogen with oxygen should be endothermic anyway.

It is impossible as the air loses energy too quickly to sustain a thermonuclear chain reaction.

 

[TeethWhitener]

This is the paper (declassified after many years) by Teller et al. with the calculations:
https://fas.org/sgp/othergov/doe/lanl/docs1/00329010.pdf
The worry was that the fission fireball would burn hot enough to initiate N-14 fusion, releasing more heat and perpetuating the reaction until the entire atmosphere was ignited. The paper concludes that this is impossible given the density of the atmosphere, even under generous (read: unrealistic) assumptions about the then-unknown reactivity of N14.

 

[Nik_2213]

I'd thought you meant the entire atmosphere, either by Teller's concern or some B-Movie plot...

On a local scale, Russians etc are reporting craters & collapses due to clathrate thawing producing methane burps and 'fuel-air' explosions. Happily, no victims to date. IIRC, several 'curious' North Sea features have been attributed to this process, albeit from around the same time as the vast Storegga Slides...

 

[jim mcnamara]

@Nik_2213 - do you have a link on this - it is interesting.

 

[Nik_2213]

https://phys.org/news/2017-06-massive-craters-methane-blow-outs-arctic.html
There are similar findings off Scandinavia etc.
https://www.nature.com/news/mysterious-siberian-crater-attributed-to-methane-1.15649

I can't locate a primary, non-paywalled link for the North Sea, but searching for 'Witch Ground Formation' will find many peer-reviewed petrochemical industry reports...

{ Regret search will also offer a surfeit of variously apocalyptic tosh. Mind you, there *is* a lot of methane clathrate about...}