Answer to Question #76 in Molecular Physics | Thermodynamics for Silvia Rosso

Question

Why, if you breath on your hand, you get a feeling of warmth, and if the blow - the feeling of cold?

Answer 1

When you breathe in the hand, the hand feels the air, the temperature of which is equal to the temperature of the body (36.6), which is warmer than the surrounding air, whence a feeling of warmth comes. When you huff, first you blow hot air with the hand, and secondly the process of evaporation starts, which leads to cooling, and the hand feels cool.