1. Water Cycle Chapter 15

2. Movement of Water on Earth  Water Cycle: the continuous movement of water between the atmosphere, the land, and the oceans  2/3 of Earth is cover in water  The atmosphere has water vapor and liquid water (found in clouds and fog)  Earth’s water is constantly cycling

4.  Evapotranspiration: the total loss of water from an area by evaporation and transpiration into the atmosphere.  Evaporation: comes from bodies of water such as lakes, rivers, and oceans.  Transpiration: comes from animals, plants and soils.  Each year, about 500,000km 3 of water evaporates into the atmosphere. About 86% comes from the oceans.

5.  Condensation: the change of state from a gas to a liquid  When water vapor rise into the atmosphere it cools and expands. As it cools some will condenses and forms water droplets that form into clouds.

6.  Precipitation: any form of water that falls to Earth’s surface from the clouds; includes rain, snow, sleet, and hail.  About 75% goes into oceans  About 25% ends up as runoff and ground water.  All water will end back up in the atmosphere to begin the water cycle again.

8. Water Reservoirs Reservoirs% Ocean97 Glaciers/Ice caps2 Groundwater.7 Atmosphere.01 Freshwater Lakes.3 Saline lakes and inland sea.01 Rivers.001

9. Water Budget  Precipitation: income  Evapotranspiration and runoff: expenses  Precipitation = Evapotranspiration and runoff  ‘World’s’ Water budget is balanced!  Local water budget (an given area) is not balanced!

10. Watershed: Local Water Budget

11. Factors that Affect the Water Budget  General Factors: Temperature, vegetation, wind, and the amount and duration of rainfall  Local factors: geography (landscape) and seasons

12. Water Use  Average person usage in US in a year: 95,000 L (20,890.5 gallons)  Population increase = more demand on water  90% of water used in cities and industry is returned as wastewater into rivers and oceans, which includes pollution

13. Conservation of Water  Two ways to ensure fresh water for the future  Conservation or use water wise  Find alternative methods of obtaining fresh water  Desalination  a process of removing salt from ocean water  Expensive and impractical for large populations  What other ways can you think of?