ETYM French climat, Latin clima, -atis, from Greek, slope, the supposed slope of the earth, hence a region or zone of the earth, from klinein to slope, incline.
1. The prevailing psychological state; SYN. mood.
2. The weather in some location averaged over some long period of time; SYN. clime.
Weather conditions at a particular place over a period of time. Climate encompasses all the meteorological elements and the factors that influence them. The primary factors that determine the variations of climate over the surface of the Earth are: (a) the effect of latitude and the tilt of the Earth's axis to the plane of the orbit about the Sun (66.5ş); (b) the large-scale movements of different wind belts over the Earth's surface; (c) the temperature difference between land and sea; (d) contours of the ground; and (e) location of the area in relation to ocean currents. Catastrophic variations to climate may be caused by the impact of another planetary body, or by clouds resulting from volcanic activity. The most important local or global meteorological changes brought about by human activity are those linked with ozone depleters and the greenhouse effect.
How much heat the Earth receives from the Sun varies in different latitudes and at different times of the year. In the equatorial region the mean daily temperature of the air near the ground has no large seasonal variation. In the polar regions the temperature in the long winter, when there is no incoming solar radiation, falls far below the summer value. Climate types were first classified by Wladimir Köppen (1846–1940) in 1884. The temperature of the sea, and of the air above it, varies little in the course of day or night, whereas the surface of the land is rapidly cooled by lack of solar radiation. In the same way the annual change of temperature is relatively small over the sea and great over the land. Continental areas are thus colder than the sea in winter and warmer in summer. Winds that blow from the sea are warm in winter and cool in summer, while winds from the central parts of continents are hot in summer and cold in winter. On average, air temperature drops with increasing land height at a rate o.
F 1şC/1.8şF per 90 m/300 ft. Thus places situated above mean sea level usually have lower temperatures than places at or near sea level. Even in equatorial regions, high mountains are snow-covered during the whole year. Rainfall is produced by the condensation of water vapor in air. When winds blow against a range of mountains so that the air is forced to ascend, rain results, the amount depending on the height of the ground and the dampness of the air. The complexity of the distribution of land and sea, and the consequent complexity of the general circulation of the atmosphere, have a direct effect on the distribution of the climate. Centered on the equator is a belt of tropical rainforest, which may be either constantly wet or monsoonal (seasonal with wet and dry seasons in each year). On each side of this is a belt of savannah, with lighter seasonal rainfall and less dense vegetation, largely in the form of grasses. Usually there is then a transition through steppe (semiarid) to desert (arid), with a furth.
Er transition through steppe to Mediterranean climate with dry summer, followed by the moist temperate climate of middle latitudes. Next comes a zone of cold climate with moist winter. Where the desert extends into middle latitudes, however, the zones of Mediterranean and moist temperate climates are missing, and the transition is from desert to a cold climate with moist winter. In the extreme east of Asia a cold climate with dry winters extends from about 70ş N to 35ş N . The polar caps have tundra and glacial climates, with little or no precipitation (rain or snow).
Climate changes over the last millennium can be detected by geophysicists using downhole measurement.
ETYM Old Eng. skie a cloud, Icel. sky; akin to Swed. and Dan. sky; cf. AS. scűa, scűwa, shadow, Icel. skuggi; probably from the same root as Eng. scum. Related to Scum, Hide skin, Obscure.
Outer space as viewed from the earth.