1. Water, water everywhere?
The Water Cycle
Water, water everywhere?

2. The Hydrosphere
Oceans cover approximately 71% of Earth’s surface.

3. Most of Earth’s water is in the oceans. Less than 3% is freshwater
Most of Earth’s water is in the oceans. Less than 3% is freshwater. And less than 1/3 of that can be used as drinking water.

4. The Water Cycle
The process by which Earth’s water moves in and out of the atmosphere.

5. The Sun’s Role
The sun provides the energy that powers the water cycle.

6. Evaporation
The Sun warms Earth’s surface. Water molecules heat up and change from a liquid to a gas (water vapor). The water vapor is circulated by winds and carried upward by rising, warm air.

7. Condensation
As the air carrying water vapor rises and cools it changes back to water droplets and forms clouds.

8. Rain
Precipitation
When the water droplets become large enough they fall back to the surface as precipitation.
This can be rain, sleet, snow or hail.
Sleet
Snow
Hail

9. Runoff
If the precipitation falls on land it may become runoff, water that runs downhill into rivers or streams.

10. Groundwater
If precipitation seeps (infiltrates) into the earth it may become groundwater, water that has filled pore spaces in the ground.
Porosity and saturation effect infiltration. If the surface is non-porous saturated or steep it will become runoff.

11. Transpiration Groundwater is available to plants.
Plant’s roots take in water that has seeped into the soil.
The water is transported to the leaves and released back into the atmosphere by the process of transpiration.

12. Groundwater seeps through Earth’s crust and may end up in rivers, lakes or the ocean.
When this happens the water cycle starts all over again.