Earth Science
Water on Earth
Processes of the Water Cycle
Study Tip
Based on your knowledge and observations of water in our atmosphere, create a flow chart depicting water’s movement on the Earth. Then compare your sketch to the water cycle figure shown below.
The Water Cycle
The hydrological (water) cycle is the movement of water around Earth’s surface. Water inhabits reservoirs, such as ponds, oceans, or the atmosphere, within the cycle. Molecules move between these reservoirs by certain processes including condensation and precipitation.
- Solar Energy
- The Sun provides the energy that drives evaporation and ultimately the water cycle
Study Tip
Based on your knowledge and observations of water in our atmosphere, create a flow chart depicting water’s movement on the Earth. Then compare your sketch to the water cycle figure shown below.
- Oceans
- Most of Earth’s water is stored in the oceans
- Water can remain here for hundreds or thousands of years
- Atmosphere
- Evaporation: water changes from liquid to gaseous water vapor, supplied with energy from the Sun
- Condensation: water vapor becomes tiny droplets of liquid, which gather in clouds
- Precipitation: after water droplets in clouds collide and grow, they fall as rain, sleet, hail, or snow
Because it is a cycle, the water cycle has no beginning and end.
- Streams and lakes
- When water falls from the sky as rain, it may enter streams and rivers that flow downwards to oceans and lakes
- Snow may sit on a mountain for several months and may become part of the ice in a glacier, where it remain for hundreds or thousands of years
- Sublimation: process by which a solid changes directly into a gas without first becoming a liquid (snow and ice goes back into the air)
- Snow and ice gradually melt to become liquid water which provides a steady flow of fresh water to streams, rivers, and lakes below
- A water droplet falling as rain could become part of a stream or lake
