The hydrologic cycle, or water cycle, is the sum of the movement of water through the Earth system. Because the water can carry stored heat, it is a cycle of energy as well. The information herein was taken from this site. Be sure to visit his site, and learn more.
Energy is required to evaporate water from the oceans.
Eighty Eight percent of all water entering the atmosphere is originates from the ocean between 60 degrees north and 60 degrees south latitude. Evaporation is an important means of transferring energy between the surface and the air above. The water vapor may condense back into a liquid and in so doing releases latent heat which is converted into sensible heat that warms the surrounding air. As droplets of water coalesce into larger droplets they attain a size big enough to fall towards the earth's surface. Located high in the troposphere they possess a high degree of potential energy that is converted into kinetic energy once they begin to fall toward the surface.