What is the water cycle?

Key Terms Water cycle Evaporation Condensation Precipitation Transpiration Infiltration Runoff

The Water Cycle Water is always changing state. As water evaporates from the surface, it changes from a liquid to a gas. In the atmosphere, the water vapor condenses to a liquid and forms clouds. Finally, the water falls back to Earth as precipitation. This repeated movement of water between the earth and the atmosphere is called the water cycle.

The Water Cycle Illustrated

Evaporation Evaporation is the process when liquids change to gases. Most of Earth’s surface is covered with water. When liquid water absorbs enough heat energy from the Sun, it changes into water vapor.

Transpiration Transpiration is the process of water loss from plants

Condensation The changing of a gas to a liquid is. Water vapor condenses into tiny droplets of water. These droplets join together to form clouds. A cloud is a collection of water droplets or ice crystals.

Condensation

Precipitation Water that falls to Earth from the atmosphere. Rain and snow are the two main forms of precipitation. As the water droplets in the clouds grow bigger, they become too heavy to stay in the air and gravity pulls them toward the Earth.

Precipitation

Surface Water The water on top of the earth such as streams, lakes, and ponds.

Runoff The movement of land water to the oceans, mainly in the form of rivers, lakes, and streams. Runoff consists of precipitation that neither evaporates nor penetrates the surface to become groundwater.

Soaking it Up = Infiltration Infiltration happens when water soaks into the soil from the ground level. It moves underground and moves between the soil and rocks.

Ground Water The water under the surface of the earth that is found within the pore spaces and cracks between particles of soil, sand, gravel, and bedrock.

Water Table The very top of the zone of saturation, or the level of underground water. The water table can rise or fall, depending on rainfall, evaporation, or pumping action.

Aquifer The ability of a rock layer or sediment that stores groundwater and allows groundwater to flow through it!

Erosion The process that moves soil, sediments, or rocks from one location to another by wind, water, ice or gravity!

Watershed This is an area of land that is drained by a water system, such as streams and creeks that feed a larger river that empties into a lake or an ocean.

Permeable It is a measure of the ability for rocks or sediments to let fluids pass through its open spaces or pores!

Impermeable A layer of rocks or sediments that doesn’t allow the flow of fluids to move through it.

Porosity This is the percentage of the total volume of rocks or sediments that contain open spaces in between them!

Aquitard This is a layer of earth material that will hold water but not let if flow at a useful rate or fast enough to be pumped from a well. They often form a confining layer through which little water moves. Clay soils, shale, and igneous or metamorphic rocks with little interconnected porosity or fractures are likely to form aquitards.

The End