Climate

climate, average condition of the atmosphere near the earth's surface over a long period of time, taking into account temperature, precipitation (see rain), humidity, wind, barometric pressure, and other phenomena.

Primary Influence on Climate

The major influence governing the climate of a region is its latitude. A broad latitudinal division of the earth's surface into climatic zones based on global winds includes the equatorial zone, or doldrums, characterized by high temperatures with small seasonal and diurnal change and heavy rainfall; the subtropical, including the trade-wind belts and the horse latitudes, a dry region with uniformly mild temperatures and little wind; the intermediate, the region of the prevailing westerlies that, because of several secondary influences, displays wide temperature ranges and marked changeability of weather; and the polar, a region of short summers and long winters, where the ground is generally perpetually frozen (see permafrost). The transitional climate between those of the subtropical and intermediate zones, known as the Mediterranean type, is found in areas bordering the Mediterranean Sea and on the west coasts of continents. It is characterized by mild temperatures with moderate winter rainfall under the influence of the moisture-laden prevailing westerlies and dry summers under the influence of the horse latitudes or the trade winds.

Secondary Influences on Climate

The influence of latitude on climate is modified by one or more secondary influences including position relative to land and water masses, altitude, topography, prevailing winds, ocean currents, and prevalence of cyclonic storms. Climatic types combining the basic factor of latitude with one or more secondary influences include the continental and the marine. Except in the equatorial region, the continental type is marked by dry, sunny weather with low humidity and seasonal extremes in temperature; noteworthy are the Sahara and Siberia (with the lowest recorded surface temperature, -93.6°F, or -70°C, at Verkhoyansk). Marine climates are characterized by small annual and diurnal temperature variation and by copious rainfall on the windward side of coastal highlands and mountainous islands; notable is the mean annual precipitation of 451 in. (1146 cm) at Mt. Waialeale, Hawaii.

The coastal, or littoral, climate is one in which the direction of the prevailing winds plays a dominant role—the east coasts having generally the heavier rainfall in the trade-wind belts, the west coasts in westerly belts. Both coasts have a climate resembling the continental during the season when the wind is blowing from the interior of the continent. An instance of the coastal type, in which the precipitation is accentuated by the nearness of a mountain barrier, is the west coast of North America from Alaska to Oregon, where the mean annual precipitation averages 80 to 100 in. (203 to 254 cm), almost all of it falling during the winter months. Elevation is the dominant factor in mountain and plateau climates, with the temperature decreasing about 3°F per 1,000 ft (1.7°C per 305 m) of ascent and rainfall increasing with altitude up to about 6000 ft (1829 m), then decreasing with further elevation.

Climatology and Climatic Change

Climatology, the science of climate and its relation to plant and animal life, is important in many fields, including agriculture, aviation, medicine, botany, zoology, geology, and geography. Changes in climate affect, for example, the plant and animal life of a given area. The presence of coal beds in North America and Europe along with evidence of glaciation in these same areas indicates that they must have experienced alternately warmer and colder climates than they now possess.

Despite yearly fluctuations of climatic elements, there has been, apparently, little overall change during the period of recorded history. Numerous climatic cycles (variations in weather elements that recur with considerable regularity) have been claimed to exist, including an 11-year cycle related to sunspot activity. There is currently much concern that human activities are changing the earth's climate in harmful ways. Computer models of climate changes have been developed in recent years; some examine potential parameters that effect global warming or cooling.

Bibliography

See H. H. Lamb, Climate History and the Future (1985); J. R. Herman and R. A. Sun, Weather and Climate (1985).

The Columbia Encyclopedia, 6th ed. Copyright© 2013, The Columbia University Press.

Selected full-text books and articles on this topic

Climate, Change and Risk
Thomas E. Downing; Alexander A. Olsthoorn; Richard S. J. Tol.
Routledge, 1999
Weather, Climate, Culture
Sarah Strauss; Ben Orlove.
Berg, 2003
Climates and Weather Explained
Edward Linacre; Bart Geerts.
Routledge, 1997
The Way the Wind Blows: Climate, History, and Human Action
Roderick J. McIntosh; Joseph A. Tainter; Susan Keech McIntosh.
Columbia University Press, 2000
Due to the Weather: Ways the Elements Affect Our Lives
Abraham Resnick.
Greenwood Press, 2000
The Little Ice Age: How Climate Made History 1300-1850
Brian Fagan.
Basic Books, 2000
The Role of the Sun in Climate Change
Douglas V. Hoyt; Kenneth H. Schatten.
Oxford University Press, 1997
Feeling the Heat: Dispatches from the Frontlines of Climate Change
Jim Motavalli.
Routledge, 2004
Storm Watchers: The Turbulent History of Weather Prediction from Franklin's Kite to El Niño
John D. Cox.
Wiley, 2002
Climate since A.D. 1500
Raymond S. Bradley; Philip D. Jones.
Routledge, 1995 (Revised edition)
El Niño, 1997-1998: The Climate Event of the Century
Stanley A. Changnon.
Oxford, 2000
Floods, Famines, and Emperors: El Nino and the Fate of Civilizations
Brian Fagan.
Basic Books, 1999
The Oryx Resource Guide to El Niño and La Niña
Joseph S. D'Aleo; Pamela G. Grube.
Oryx Press, 2002
Climate, History, and the Modern World
H. H. Lamb.
Routledge, 1995 (2nd edition)
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