Evaporative cooling is a process that uses the natural cooling effect of water evaporation to reduce air temperature. There are two main types of evaporative cooling: direct and indirect. Direct evaporative cooling is the most common type and involves passing air through a wetted medium, such as a cooling pad, to reduce the air temperature. Indirect evaporative cooling is a more complex process that uses a heat exchanger to transfer heat from the air to the water, which is then evaporated. This type of evaporative cooling is more efficient than direct evaporative cooling, but requires more energy to operate.