Unit 4 Vocabulary:

• Acid Rain - precipitation carrying large amounts of dissolved acids which damages buildings, forests, and crops, and kills wildlife

• Aquifers - underground layers of porous rock, gravel, or sand that contain water

• Clear-Cutting - practice of taking out whole forests when harvesting timber

• Cyclone - storm with heavy rains and high winds that blow in a circular pattern around an area of low atmospheric pressure

• Deforestation - loss or destruction of forests, mainly for logging or farming

• Desertification - process in which arable land is turned into desert

• Environmentalists - people concerned with the quality of the environment

• Extinction - disappearance or end of a species of animal or plant

• Food Web - interlinking chains of predators and their food sources in an ecosystem

• Greenhouse Effect - capacity of certain gases in the atmosphere to trap heat, thereby warming the earth

• Global Warming - gradual warming of the earth and its atmosphere that may be caused in part by pollution and in increase in the greenhouse effect

• Groundwater - freshwater that lies beneath the earth’s surface

• Habitats - area with conditions suitable for certain plants or animals to live

• Poaching - illegal killing of protected animals

• Reforestation - replanting young trees or seeds on lands where trees have been cut or destroyed

• Slash and Burn - traditional farming method in which all trees and plants in an area are cut and burned to add nutrients to the soil

• Smog - haze caused by the interaction of ultraviolet solar radiation with chemical fumes from automobile exhausts and other pollution sources

• Sustainable Development - using resources at a rate that does not deplete them for future generations

• Typhoon - violent tropical storm that forms in the Pacific Ocean, usually in late summer

• Ozone Layer - atmospheric layer with protective gases that prevents solar rays from reaching the earth’s surface