Yeah “dissipate away” is probably a bit misleading but I meant that the heat source is mainly the surface since it’s difficult to heat the thin outer layers directly, and from there heat moves up thorough ir radiation or adiabatic expansion. But it’s not like mountains are cooled down by adiabatic expansion, since the air wouldn’t move up without a temperature gradient, which means that it cannot get colder that the mountains already are. So I would think they are simply farther away form surface heat radiation and have thinner air that don’t assorb heat…