Evaporation is part of the water cycle and is the process of a liquid becoming a gas or vapor.
For evaporation to work, there has to be some sort of heat from the surface. This heat is known as latent heat. Evaporating water removes surface heat. By removing the surface heat, it lowers the temperatures and water levels, whether it's on land or a body of water.
The only reason it doesn't build and stay in the atmosphere is because of condensation and precipitation.
Hope this helps!