| Acid Deposition | Sulfur oxides and nitrogen oxides, emitted by burning fossil fuels, enter the atmosphere-where they combine with oxygen and water to form sulfuric acid and nitric acid and return to earth's surface. |
| Acid Precipitation | Conversion of sulfur oxides and nitrogen oxides to acids that return to earth as rain,snow, or fog. |
| Active solar energy systems | Solar energy system that collects energy through the use of mechanical devices like photovoltaic cells or falt plate collectors. |
| Agribusiness | Commercial agriculture characterized by integration of different steps in the food-processing industry, usually through ownership by large corportations |
| Agricultural Density | The ratio of the number of farmers to the total amount of land suitable for agriculture |
| Agricultural Revolution | The time when humans beings first domesticated palnts and animals and no longer relied entirely on hunting and gathering |
| Agriculture | The deliberate effort to modify a portion of Earth's surface through the cultivation of crops and the raising of livestock for sustenance or economic gain. |
| Air Pollution | Concentration of trace substances, such as carbon monoxide, sulfur dioxide, nitrogen oxides, hydrocarbons, and solid particules, at a greater level that occurs in average air. |
| Animate Power | Power supplied by people or animals. |
| Animisn | Belief that objects, such as plants and stones, or natural evnts like thunderstorms and earthquakes, have a discrete spirit or conscious life |
| Annexation | Legally adding land area to a city in the United States |
| Apartheid | Laws (no longer in effect) in South Africa that physically separated different races into different geographic areas. |
| Arithmetic Density | The total number of people divided by the total land area. |
| Autonomous Religion | A relgion that does not have a central authority but shares ideas and cooperates informally. |
| Balance of Power | Condition of roughly equal strength between opposing countries or alliances of countries. |
| Balkanization | Process by which a state breaks down through conflicts among it. |
| Balkanized | A small geographic area that could not successfully be organzied into one or more stable states because it was inhabited by ethnicities with complex long standing antagonism toward each other ethnicities. |
| Basic Industries | Industries that sell their product or service primarily to consumers outside the settlement |
| Biochemical Oxygen Demand (BOD) | Amount of oxygen required by aquatic bacteria to decompose a given load of organic waste; a measure of water pollution. |
| Biomass Fuel | Fuel that derives from plant material and animal waste. |
| Blockbusting | A process by which real estate agents convince white property owners to sell their homes at low prices because of fear that black families will move into the neighborhood. |
| Boundary | Invisibile line that marks the extent of a state's territory. |
| Break-of-bulk point | A location where transfer is possible from one mode of transportation to another. |
| British Received Pronunciation (BRP) | The dialect of English associated with upper-class Britons living in the London area now considered a standard in the UK. |
| Branch (of a religion) | A large and fundamental division within a religion. |
| Breeder Reactor | A nuclear power plant that creates its own fuel from plutonium. |
| Bulk-gaining industry | An industry in which the final product weighs or comprises a greater volume than the input. |
| Business Services | Services that primarily meet the needs of other businesses. |
| Cartography | The science of making maps. |
| Caste | The class or distinct hereditary order into which a Hindu is assigned according to religious law. |
| Census Tract | An area delineated by the U.S. Bureau of hte Census for which statistics are published; in urbanized areas, census tracts correspond roughly to neighborhoods. |
| Census | A complete enumeration of a population. |
| Central Business District (CBD) | The area of hte city where retail and office activities are clustered. |
| Central Place Theory | A theory that explains the distribution of services, based on the fact that settlements serve as centers of market area for services; larger. Settlements are fewer and farther apart than smaller settlements and provide services for a larger number of people who are willing to travel farther. |