Re: The old terraforming question.
the speed is in my posts below, if you drop a nuke into the atmosphere of mars, it will just create acid rain, as methane becomes a liquid at room temperature
https://en.wikipedia.org/wiki/Methanesulfonic_acid
there are no volcano`s, you most methane would stay at ground level so mars would become twice as cold as it already it, other planets in out solar system with methane atmosphere`s have plenty of acid rain because of volcano`s
http://science.opposingviews.com/planet-acid-rain-fall-3700.html
the force of the blast, low atmosphere level, and thermo nuclear temperators would probably make some hydrogen and CO2
https://en.wikipedia.org/wiki/Steam_reforming
if you know what all this means, and know your parts per million of methane on mars, you could drop a 100 cubic tons or more of hydrogen and CO2, with the war head 100m behind, so the hyrdogen and CO2 have some time to disperse