1. AIM: How the “spheres” interact: The Water Cycle

2. Chief Ideas
Water plays a wide variety of roles in the global ecosystem.
Water makes up the oceans and seas of the hydrosphere.

3. Where is the Water
Most of the world's supply of water is stored in the oceans (97.2%).
Small quantities of water are in the form of ice (2.15%) and groundwater (0.63%).
Smaller quantities of water are found in lakes and rivers (0.0001%),
The amount of water in the atmosphere (0.001%) shapes both local and global weather

4. Chief Ideas
Water vapor is the most important gas in the atmosphere for weather.
Plants and animals in the biosphere consist of 65-90% water.
Water is also a universal solvent and helps to shape the lithosphere.

5. Chief Ideas The amount of water on earth is finite.
Water constantly moves from the hydrosphere to the atmosphere, the atmosphere to the lithosphere, and the biosphere, then back to the atmosphere and hydrosphere.
Hydrologic Cycle (Water Cycle)

6. Chief Ideas As water moves, it changes state
Sometimes, water is a liquid, sometimes a solid (ice), and sometimes a gas (water vapor).

7. The Phase Change Diagram
Every time water changes its state, heat is either absorbed or released by water molecules.
Heat is absorbed when water changes to water vapor during evaporation
Heat is released during Condensation when water vapor changes to droplets.
When water freezes it releases latent heat and when it melts, it absorbs heat.

8. The driving force for the hydrologic cycle is
solar energy
assisted by gravity.

9. Water evaporates from the surface to the atmosphere Most of all evaporation (80%) is from the oceans

10. Condensation is the change of water from gas (vapor) form into liquid water.

11. Precipitation is the primary mechanism for transporting water from the atmosphere to the surface of the earth.
Rain, snow, hail, sleet, etc.

12. Infiltration occurs when surface water penetrates the earth's surface
Infiltration occurs when surface water penetrates the earth's surface. As the groundwater water increases or decreases, the water table rises or falls accordingly. When the entire area below the ground is saturated, flooding and run-off occurs.

13. Runoff is the movement of land-water to the oceans, chiefly in the form of rivers, lakes, and streams and then the ocean. Runoff consists of water that does not penetrate the surface to become groundwater

14. Plants absorb soil-water through their roots
Plants absorb soil-water through their roots. Transpiration is the evaporation of water into the atmosphere from the leaves and stems of plants. Transpiration accounts for approximately 10% of all evaporating water.

16. Summary
The hydrologic cycle begins with the evaporation of water from the surface of the ocean.
The water vapor condenses to form clouds.
Moisture returns to the surface of the Earth as precipitation.
Once the water reaches the ground, one of three things may occur:

17. Summary some of the water may evaporate back into the atmosphere
the water may penetrate the surface and become groundwater which will eventually seep its way to into the oceans, rivers, and streams, or is transpired through plants back to the atmosphere.
The balance of water that remains on the earth's surface is runoff, which empties into lakes, rivers and streams and is carried back to the oceans, where the cycle begins again.