Here in the desert southwest we enjoy the benefits of the dry desert air to take advantage of alternate cooling mechanism like evaporative (swamp) coolers and outdoor misting / fog systems for our patios and outdoor areas. Fog systems work by flash evaporating the fine drops of water into the air called “adiabatic cooling”. As it flash evaporates it cools the air around the droplet causing the temperature drop. Despite common beliefs it is NOT the water that cools you but the evaporation process – much the same reason you feel cold as you get out of a swimming pool.
With the help of MicroCool we've come up with a simple way for you to determine if turning on your fog / mister system will cool the air around you effectively. Misters are only effective if moisture levels in the air are low enough to allow the tiny water droplets (1/10 the diameter of a human hair) to evaporate and cool the surrounding air. When the humidity level is too high the droplets do not evaporate fast enough and can cause wetting on the ground and reduced cooling. Using the current temperature and dew point data we can provide a simple yes or no for you to determine that your misting system operates effectively as possible.
Special thanks to MicroCool in Thousand Palms for providing the information necessary to put this information together.