First of all, just registered, first post. So hi all, just started undergrad course in physics at kent so may pop up here quite a bit :) So, I was just outside, having a smoke, standing in the doorway of the house. Now I've noticed this before and not thought it about as much but the smoke from my roll-up always flows back in to the much warmer house. From my understanding of thermodynamics heat always flows from hot to cold. So I would expect the smoke to all go away from the house as outside is considerably colder. I had some thoughts trying to explain it but won't chance my arm hehe. So, anyone know or have an idea as to why this is?