Evaporative cooling is the process of cooling by the evaporation of water, which increases the humidity, but decreases the dry bulb temperature. There are several types of evaporative cooling. Typically, evaporative cooling refers to direct evaporative cooling, often referred to as a swamp cooler. In a swamp cooler, warm (dry) air is forced through a wet medium, and is cooled as it evaporates water. The exiting air has a lower dry bulb temperature, but a higher dew point. This type of cooling is common in the American Southwest