| A | B |
|---|
| weather | short-term changes in the air for a given place and time |
| climate | a region's average weather conditions over a long period |
| prevailing winds | winds that blow in the same direction over large areas of the Earth |
| ocean currents | large streams of surface seawater |
| front | where two air masses of different temperature and moisture content meet |
| monsoons | seasonal winds that bring either dry or moist air |
| savanna | tropical areas that support tall grasses and scattered trees and shrubs |
| steppe | semidry grasslands or prairies often bordering deserts |
| permafrost | permanently frozen layers of soil |
| environment | the land, water, climate, plants, and animals or an area |
| ecosystem | a group of plants and animals that depend on each other for survival and the environment in which they live |
| habitat | the place where a plant or animal lives |
| desertification | the spread of desertlike conditions |
| natural resource | any material in nature that people use and value |
| renewable resources | resources the Earth replaces naturally |
| nonrenewable resources | resources that cannot be readily replaced |
| deforestation | the clearing of trees |
| reforestation | planting trees to replace lost forestland |
| fossil fuels | nonrenewable resources that formed from the remains of ancient plants and animals |
| hydroelectric power | the production of electricity from waterpower |
