Maxwell devised a simple and well-known thought experiment now called Maxwell's Demon, to prove why cold gases (such as the atmosphere at -18C on average), cannot make warmer gases or bodies (such as the Earth surface at +15C average) any warmer in violation of the second law of thermodynamics.
The 2nd law of thermodynamics states disorder (called entropy) of any system (such as Earth's atmosphere) must always increase, and for any heat transfer to occcur from cold gases or bodies to warmer gases or bodies would result in an impossible decrease of entropy forbidden by the 2nd law of thermodynamics.
So, the next time someone claims a cold gas/body can make a warm body warmer, ask them for their solution to Maxwell's demon first:
|Schematic of Maxwell's demon|
From Wikipedia entry on Maxwell's demon:
In the philosophy of thermal and statistical physics, Maxwell's demon is a thought experiment created by the physicist James Clerk Maxwell to "show that the Second Law of Thermodynamics has only a statistical certainty".1 It demonstrates Maxwell's point by hypothetically describing how to violate the Second Law: a container of gas molecules at equilibrium is divided into two parts by an insulated wall, with a door that can be opened and closed by what came to be called "Maxwell's demon". The demon opens the door to allow only the faster than average molecules to flow through to a favored side of the chamber, and only the slower than average molecules to the other side, causing the favored side to gradually heat up while the other side cools down, thus decreasing entropy.