Water Cycle Overview and Processes

Water Cycle Overview

• The water cycle is the continuous movement of water within the Earth's hydrosphere.
• It involves the exchange of water among the oceans, atmosphere, solid Earth, and biosphere.
• The hydrosphere encompasses all the water on planet Earth.
• The cycle is unending and continually circulates the water supply.

Water Cycle Processes

• Evaporation/Transpiration: Liquid water transforms into a gaseous state. Water evaporates from bodies of water and transpires from plants. This occurs due to solar heating.
• Precipitation: Water vapor in the atmosphere cools and condenses into liquid water droplets (rain), solid ice crystals (snow or hail), or frozen dew. Droplets combine and become heavy, falling to Earth.
• Infiltration: Surface water soaks into the ground. The water moves into cracks and spaces in the soil or rock.
• Runoff: Water that does not infiltrate flows over the land, eventually reaching rivers and lakes. This happens when rainfall exceeds the Earth's ability to absorb it.
• Condensation: Water vapor cools and changes back into liquid water, creating clouds.

Water Absorption

• Water can infiltrate the ground and enter rivers, lakes, and streams.
• Plants also absorb water.

Key Terms

• Saturated: Unable to hold or contain more; full.
• Unsaturated: Capable of absorbing or dissolving more of something.
• Permeable: Having pores or openings that permit liquids or gases to pass through.
• Impermeable: Not permitting passage (as of a fluid) through its substance.
• Dynamic Equilibrium: Occurs when the average annual precipitation over the Earth equals the amount of water that evaporates.