Water on Earth: Section 2 The Hydrosphere Forms saltwater—97 percent of world’s water freshwater—most frozen in ice caps; less than 1 percent in vapor and liquid form Where liquid fresh water is found surface water—in rivers, lakes, estuaries, wetlands groundwater—stored in soil and water table

The Hydrosphere Hydrologic Cycle SECTION 2 Condensation: as water vapor rises it forms droplets. Evaporation: energy transforms water into vapor. Precipitation: droplets may become heavy enough to fall as rain, snow, or hail. Surface Water Solar Energy, Wind, Gravity Drive the Cycle

Floods: Section 2 The Hydrosphere Causes—heavy rains, sudden snow melts; human activity may contribute Effects—erosion, loss of vegetation, death and destruction

Importance of soil and forests: Section 3 Natural Resources Importance of soil and forests: Soil is crucial for food production. Forests protect soil from erosion, provide species habitats, and yield useful products.

Concerns about air and water quality: Section 3 Natural Resources Concerns about air and water quality: air pollution—threatens air supply, creates acid rain, damages the ozone layer, may contribute to global warming water pollution— threatens clean water supply, contributes to shortages

Minerals Section 3 Natural Resources Minerals are used in many processes and products, including construction, jewelry, and manufacturing. Examples: building materials, airplanes, cans, glass.

Energy resources Section 3 Natural Resources Energy resources include fossil fuels—coal, natural gas, petroleum—and uranium. Uses: uranium—energy for nuclear power coal—heat source; power for steam engines, mills, electricity generation; dye making petroleum—lamp fuel; gasoline, diesel and heating fuel; asphalt, petrochemicals natural gas—home and industrial heating; fuel