Environment and Ecology

The Earth’s Environment

What is the hydrologic cycle?

The hydrologic cycle takes place in the hydrosphere, which is the region containing all the water in the atmosphere and the Earth’s surface. Simply put, it involves five phases: condensation, infiltration, runoff, evaporation, and precipitation. Solar energy drives winds that evaporate water from the surface of the oceans. The water vapor cools and condenses as it rises and then falls to the ground as rain, snow, or some other form of precipitation—rain, snow, hail, etc., which then infiltrates into the ground (replenishing ground water) or runs off into streams, creeks, rivers, and oceans. From there, it evaporates again, thus completing the cycle.


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