1. 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

2. 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

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

4. 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.

5. 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

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

7. 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