What Is Evaporative Cooling?
When water evaporates from the surface of something, that surface becomes much cooler because it requires heat to change the liquid into a vapor. A nice breeze on a hot day cools us because the current of air makes perspiration evaporate quickly. The heat needed for this evaporation is taken from our own bodies.
As air comes in contact with water it absorbs it. The amount of water absorbed depends largely on how much water is already in the air. The term humidity describes the level of water in the air. If the air holds 50% of its capacity, the humidity would be 50%. If the humidity is low, then the capacity to hold more water is higher, and a greater amount of evaporation takes place.
When the air contains large amounts of moisture, the humidity is said to be high. If the air contains only a small amount of moisture, the humidity is said to be low. When the air holds as much moisture as possible at a certain temperature, the air is saturated. At saturation, the temperature and the dew point are the same. The amount of humidity varies according to the temperature and location. The warmer the air, the more moisture it is able to hold.