Evaporation is the process by which water changes from a liquid to a gas or vapor. Water boils at 212 degrees F (100 degrees C), but it actually begins to evaporate at 32 degrees F (0 degrees C); it just occurs extremely slowly. As the temperature increases, the rate of evaporation also increases. The amount of evaporation depends on the temperature, and it also depends on the amount of water there is to evaporate. For example, there is not much evaporation occurring in the Sahara Desert, but why? Although it can get extremely hot in the Sahara, it's just sand - there's just not much water to be evaporated.