How A Misting Fan Works: The coolness you feel with a standard fan is caused by a principle called evaporative cooling.  In a warm environment your body sweats and liquid perspiration forms on your skin. As the circulating air from the fan moves over your skin it evaporates the perspiration.  Energy is used in that process and the result is a coolness at the surface where the process takes place. In addition, the moving air is more efficient at removing radiated heat from your body. With a misting fan, water is added to the equation.  A fine spray of water is combined with the air movement of the fan. The most inexpensive misting fans, are powered by the pressure from a supply water line or internal compartment where the water naturally flows out, while other more expensive fans have high pressure pumps that assist in spraying the water into an ultra-fine mist.  With the more expensive misting fans flash evaporation occurs which basically cools with less moisture in the air, as the mist is dissipated Misting fans work best in areas with lower humidity levels. However, when temperatures rise above 90 degrees Fahrenheit, relative humidity usually falls below 70 percent, enabling a misting system to lower the surrounding air temperature. The lower the humidity levels, the more of a drop in temperatures will occur.