hydrologic cycle

The natural cyclic transfer of water vapor from the Earth's surface via evaporation into the atmosphere, from the atmosphere via precipitation back to earth, and through runoff into streams, rivers, and lakes, and ultimately into ground water and the oceans.


Hydrologic Cycle [cite]

This shows the dynamics of the hydrologic cycle; the evaporation and transpiration of water vapor into the atmosphere by solar heating, the cooling, and condensing of the water vapor into precipitation, and the return of freshwater to the Earth’s surface through precipitation. Surface water will run down-hill by force of gravity to the lowest point, which is usually a lake or the oceans. When the earth is permeable and allows water to percolate underground, the groundwater aquifers become recharged.