: Why do you feel cold air from an air-conditioned room coming out under a closed door into a warmer room or corridor?

Question

Room has air-conditioning going, cooler than corridor. Much cooler.

I can feel the cold air coming out from under the closed door when standing in front of it.

Why?

In: 3

Answer 1

Cool Air sinks to the bottom of the floor. And since your AC exhaust usually isn’t placed on the floor the newly cooled air sinks on top of the already cool (but a bit warmer air since the floor is reheating the air). As such you get a high pressure zone as the coolest air is trying to sink down onto the ground. This squeezes the cool air which is already on the ground through the small gap below the door into the warmer hallway.