Zone

Zone, in geography, any of the five divisions of the surface of the Earth, characterized by their differences in latitude or temperature. From north to south the zones are divided by the Arctic Circle, the tropic of Cancer, the tropic of Capricorn, and the Antarctic Circle. At the polar extremes are the North Frigid Zone (lying north of the Arctic Circle) and the South Frigid Zone (south of the Antarctic Circle). The North Temperate Zone lies between the Arctic Circle and the tropic of Cancer; the South Temperate Zone lies between the Antarctic Circle and the tropic of Capricorn. The Torrid Zone forms a belt on both sides of the equator between the tropic of Cancer and the tropic of Capricorn. This division of zones probably originated with the Greek philosopher Parmenides in the 400s bc. It is a rough representation of the Earth's temperature or climatic zones and does not take into account differences in elevation, proximity of oceans, or the movement of air masses. The distribution of climate and plant formations is considerably more complex than these five zones suggest. See also Biosphere; Ecology.