Fanning produces a sense of coolness in the body because of evaporation of moisture from the skin. On fanning the rate of evaporation increases. The water molecules from the body in the form of perspiration take up heat energy from the body and escape from the body surface, thus cooling it. However, if the air is hot, as in a desert, fanning does not produce any cooling as the heat for evaporation is supplied by the hot air.
