Ever have one or both ears get really warm and red for no reason? Well, obviously there's a reason! What is it? It seems to happen more when there is a difference of temperature, like one is outside in the cold, and then comes inside and it begins its process. I've heard it is due to a change in pressure... eh? :bugeye:
It happens when I come into a warm house after being outside in the cold for a while (like you mentioned). It seems to correlate with being tired as well. I reckon it's because the body temperature regulation that kinda lags.
Ears, like fingers and toes, are at the extreme end of the circulatory system and therefore chill easily. It's the body's reaction to that - increased bloodflow to increase their temperature - that causes the redness to appear.
I guess it's a little weird because I generally experience it in my ears (often only one in particular). It takes a while of being in the cold to have my fingers react like that.
Actually, when it's cold, the bloodvessels near the surface contract to minimize heat-loss to the cold air. When you come into a warm room from the cold outside the bloodvessels relax again and bloodflow increases. This is why your ears feel warm (like when you put your hand into ice-cold water for a while and then put it in lukewarm water the water appears to be hot). I guess they get red because the nervous-system might be overreacting due to the extreme temperature difference. It 'thinks' that it's suddenly very hot and completely relaxes the bloodvessels in order to actually lose heat.
Increase in Blood pressure will cause your ears to become warm. Enmos is correct that the body closes down the vessels in the outer parts of the body to protect the internal organs like the heart and the brain from getting to cold. And when you come in from outside your body will force the blood back into your ears causing them to feel warm. You will get the same feeling when you are embarrass or the certain someone that rings your bell but you are to afraid to talk too comes into the room. Or if your are hypertensive your ears in some case appear to be arm most of the time.
