> When we inhale cold air, these structures warm it, and thus become colder. When we exhale hot air, it heats these structures, making them warmer again How so

> When we inhale cold air, these structures warm it, and thus become colder. When we exhale hot air, it heats these structures, making them warmer again How so? When you breathe in, your nose tissues will cool down to a temperature T_N and the air you inhale will heat up to a temperature T_A. Physics (the second law of thermodynamics) dictates that T_N >= T_A. Moreover, the nose tissues are connected to a large heat reservoir (the body), so we might as well assume they go back up to body temperature very quickly, so T_N = 37°C after a second or two. Either way, when you breathe out you still have T_N >= T_A. In this situation, there is no way the air could transfer back heat to the nose without a violation of the second law or, well, a heat pump. Hence my question.