Zone

(zōn.) [Gr. zōně, a belt.] (Geog.) A circular division of the earth with reference to the temperature. There are five zones: the torrid, extending from tropic to tropic, and twice the sun's greatest declination or 470 in breadth; the two temperate zones, situated between the tropics and polar circles, each 43° in breadth; and the two frigid zones, situated between the polar circles and the poles. The zones are distinguished from one another by various phenomena. To the inhabitants of the torrid Z. the sun is vertical twice a year. In the middle of that Z. the days and nights are always equal, each being 12 hours, and the twilight is short because the sun descends perpendicularly below the horizon. Within its limits there are only two seasons in the year, viz., winter and summer.-(Math.) That part of a spherical surface which is bounded by two parallel lines. [s. 978]