In an environment with gravity, hot air is less dense than cool air, so it rises.
How does hot air interact with cold air in a zero gravity environment, in terms of movement? Does it just stay where it is? Some sort of spherical configuration, maybe with the hotter air on the outside?
For the sake of an example, imagine there's a candle burning in zero-g. I'm aware the flame will be spherical. How will the hot air around the flame act?
I found this Reddit discussion on the topic, but being Reddit there's not really a definitive answer like the kind I expect to see here.
Best Answer
In the presence of a gravitational field the hot air raises because it feels a buoyancy force. There is a difference of pressure between the bottom and the top of the hot air portion resulting in an upward force.
If there is no gravity, there is no difference of pressure (in principle) so the hot air does not raise. It just expands uniformly. If you are in an accelerating frame though you get a pressure gradient and the hot air will follow this direction even though there is no gravity.