Since the head, face and ears of the skin is very thin, covered with rich blood vessels, when a large amount of blood flow through the ears, blood vessels will be expanded and thickened, the ears red, due to the blood has a certain temperature, so the ears will feel hot. Then again, when the outside world temperature is low, blood vessels shrink after cold, pale, at this time, if you walk into the room with a higher temperature, blood vessels suddenly thickened by heat, the ear will also feel hot, red.