| A | B |
|---|
| Weather | The condition of the bottom layer of the Earth's atmosphere in one place over a short period of time. |
| Atmosphere | A multilayered band of gases, water vapor, and dust above the Earth. |
| Climate | The term used for the weather patterns that an area or region typically experiences over a long period of time. |
| Rotation | The spinning of the Earth, like a top on its axis, as it travels through space. |
| Revolution | One complete orbit of the Earth around the sun. |
| Solstice | Either of the two times a year when the sun appears directly overhead at noon to observers at the Tropics of Cancer and Capricorn. |
| Equinox | Either of the two times each year (spring and fall) when day and night are of nearly equal length everywhere on Earth. |
| Precipitation | All the forms of water that fall to Earth from the atmosphere, including rain and snow. |
| Front | The boundary between two masses of air that differ in density or temperature. |
| Continental Climate | The type of climate found in the great central areas of continents in the Northern Hemisphere; charaterized by extreme temperatures-cold, snowy winters and warm or hot summers. |
| Greenhouse Effect | The phenomenon whereby the earth's atmosphere traps solar radiation, caused by the presence in the atmosphere of gases such as carbon dioxide, water vapor, and methane that allow incoming sunlight to pass through but absorb heat radiated back from the earth's surface. |
| Hydrologic Cycle | The cycle of evaporation and condensation that controls the distribution of the earth's water as it evaporates from bodies of water, condenses, precipitates, and returns to those bodies of water. |
| Elevation | Distance of something above a reference point (such as sea level). |
| Convectional Precipitation | Results from the heating of the earth's surface that causes air to rise rapidly. As the air rises, it cools and moisture condenses into clouds and precipitation. |
| Plant Community | A mix of interdependent plants that grow naturally in one place. |
| Enviroment | The physical conditions of the natural surroundings. |
| Natural Vegetation | The typical plant life that abounds in areas where humans have not significantly altered the landscape. |
| Deciduous | Leaf-shedding; a type of tree that sheds its leaves when winter approaches. |
| Coniferous | Cone-bearing; a type of tree able to survive long, cold winters, with long, thin needles rather than leaves. |
| Chaparral | A type of natural vegetation that is adapted to Mediterranean climates; small trees and low brushes, or scrub. |
| Tundra | A region where temperatures are always cool or cold and only specialized plants can grow-either alpine tundra, in high elevations, or arctic tundra, in high latitudes. |
| Permafrost | A layer of soil just below the Earth's surface that stays permanently frozen. |
| Biome | A major regional or global biotic community, such as a grassland or desert, characterized chiefly by the dominant forms of plant life and the prevailing climate. |
