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Unit 2 Hydrosphere. The water cycle. Water Distribution. Water Distribution. Over 97 percent of the water on Earth is salt water (saline). Of the total freshwater, over 68 percent is locked up in ice and glaciers. 30 percent of freshwater is in the ground.
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Unit 2 Hydrosphere The water cycle
Water Distribution • Over 97 percent of the water on Earth is salt water (saline). • Of the total freshwater, • over 68 percent is locked up in ice and glaciers. • 30 percent of freshwater is in the ground. • Fresh surface-water sources, such as rivers and lakes, is about 1/150th of one percent of total water.
The water cycle has no starting point. • The sun drives the water cycle • The water cycle is a closed system • The same water that dinosaurs drank is the same water we drink today.
The parts of the water cycle • Evaporation is the process by which water changes from a liquid to a gas or vapor. • Most evaporation occurs from the oceans since they cover 70% of the Earth. • Sublimation, the process by which water changes from a solid (ice or snow) to a gas, bypassing the liquid phase • This often happens in the Rocky Mountains
Transpiration: the process by which moisture is carried through plants from roots to leaves, where it changes to vapor and is released to the atmosphere
Condensation is responsible for the formation of clouds. • These clouds may produce precipitation, which is the primary route for water to return to the Earth's surface. • Clouds exist in the atmosphere because of rising air. As air rises and cools the water in it can "condense out", forming clouds. • When the temperature drops below the dew-point temperature= clouds form
Precipitation Water falling back to Earth’s surface • Rain • Snow • Sleet (mixture of rain and snow) • Hail • New Record Hailstone • A hailstone which fell on July 23, 2010 at Vivian, South Dakota
Surface Run-off- water flows from high to low • Oceans, rivers, lakes • Humans and urban developments affect run off • Infiltration • a portion of the water that falls as rain and snow infiltrates into the subsurface soil and rock.
Factors that affect infiltration • Precipitation increase precipitation, increase infiltration • Type of soil large particle = more infiltration, small particles = less infiltration • Soil saturation saturated soil = less infiltration • Land cover Lots of vegetation = more infiltration • Slope of land greater slope= less infiltration