climate

1. The meteorological conditions, including temperature, precipitation, and wind, that characteristically prevail in a particular region.
2. A region of the earth having particular meteorological conditions: lives in a cold climate.
3. A prevailing condition or set of attitudes in human affairs: a climate of unrest.

[Middle English climat, from Old French, from Late Latin clima, climat-, from Greek klima, surface of the earth, region.]

noun

1. The totality of surrounding conditions and circumstances affecting growth or development: ambiance, atmosphere, environment, medium, milieu, mise en scène, surroundings, world. See be, limited/unlimited, place.
2. A prevailing quality, as of thought, behavior, or attitude: mood, spirit, temper, tone. See attitude/good attitude/bad attitude/neutral attitude.

A summary of mean weather conditions over a time period, usually based on thirty years of records. Climates are largely determined by location with respect to land- and sea-masses, to large-scale patterns in the general circulation of the atmosphere, latitude, altitude, and to local geographical features.

For more information on climate, visit Britannica.com.

The climate of an area, defined as the aggregate of weather conditions over time, is constructed from monthly, seasonal, and annual averages of weather elements, such as temperature and precipitation, combined with statements about the frequency of extreme events, such as droughts or tornadoes. Historically, climate has had important economic implications for agriculture, transportation, and settlement. Climatology, or the scientific study of climate, dates to the mid-nineteenth century and includes such specialties as applied climatology, climate dynamics, and climate change.

The classical heritage related the climate of an area uniquely to its latitude. Climate, from the Greek klima, meaning "inclination," was originally thought to depend only on the height of the sun above the horizon, modified in part by special local characteristics. Climate and health have also been closely related throughout history. According to the Hippocratic tradition of ancient Greece, a physician should consider the seasons of the year and what effects each of them produces; the location of a city with respect to winds, waters, terrain, and the rising of the sun; and the particulars of the weather. These were keys to diagnosing and treating diseases in a given location.

The Puzzle of the Early American Climate

Because of its seemingly favorable location in latitudes farther south than most European nations, the New World was expected to have a warm, exotic climate. Initially, colonists and their sponsors envisioned a rich harvest of wine, silk, olive oil, sugar, and spices from their investment. In 1588 the colonial promoter Thomas Harriot pointed out that Virginia was located on the same parallel of latitude as many exotic places, including Persia,

China, and Japan in the East and southern Greece, Italy, and Spain in the West. The reality was much different, however. Early settlers in the Americas found the climate harsher and the storms more frequent and more powerful than in the Old World. In 1644 the Reverend John Campanius of Swedes' Fort, Delaware, wrote of violent winds, unknown in Europe, which tore mighty oaks out of the ground. Another colonist in New Sweden, Thomas Campanius Holm, described rainstorms in which the whole sky was filled with smoke and flames. James Mac Sparran, a missionary to Rhode Island between 1721 and 1757, warned against immigrating to America because the climate was unhealthy, with excessive heat and cold, sudden changes of weather, unwholesome air, and terrible thunder and lightning.

Because of such reports, many Europeans held considerable disdain for the New World and for its climate, soil, animals, and indigenous peoples. The noted Parisian naturalist Georges-Louis Leclerc de Buffon speculated that, because of the cool and humid climate, the flora and fauna of the New World were degenerate. The celebrated botanist and traveler Pehr Kalm observed, rightly or not, that every life-form had less stamina in the New World. People died younger, women reached menopause earlier, soldiers lacked the vitality of their English counterparts, and even the imported cattle were smaller. He pointed to climatic influences as the probable cause.

Citizens in colonial and early America were quite defensive about these opinions and argued that clearing the forests, draining the swamps, and cultivating the land would improve the climate by changing the temperature and rainfall patterns. No general agreement, however, emerged about the direction or magnitude of the change. The Reverend Cotton Mather wrote in the Christian Philosopher (1721) that he believed it was getting warmer. Benjamin Franklin agreed, noting that compared to forested lands, cleared land absorbs more heat and melts snow quicker. In his Notes on the State of Virginia (1785), addressed to a European audience, Thomas Jefferson presented an apology for the harsh American climate and an optimistic prognosis for its improvement by human activities. Hugh Williamson of Harvard College spoke for his generation when he wrote in Observations on the Climate in Different Parts of America (1811) that settlement would result in a temperate climate and clear atmosphere that would serve as "a proper nursery of genius, learning, industry and the liberal arts." In his mind such changes added up to a continent better suited to white settlers and less suited to aboriginal inhabitants.

Climate Observations and Medical Meteorology

The first comprehensive series of meteorological observations in America, taken by John Lining, a physician in Charleston, were related to his medical concerns. In 1740, Lining collected the intake and outflow of his own body for a period of one year in an effort to understand how the weather affected bodily humors and epidemic diseases. Related efforts by Lionel Chalmers, An Account of the Weather and Diseases of South Carolina (1776); William Currie, An Historical Account of the Climates and Diseases of the United States of America (1792); and Noah Webster, A Brief History of Epidemic and Pestilential Diseases (1799) linked regional health conditions to climate and extreme weather events.

Jefferson and the Reverend James Madison began the first simultaneous comparative meteorological measurements in America in 1778. As president of the American Philosophical Society, Jefferson collected weather journals from around the county. He also directed the Lewis and Clark expedition (1804–1806) to take weather observations along the Missouri River and in the Pacific Northwest. Jefferson was a strong advocate for a national meteorological system and encouraged the federal government to supply observers in each county of each state with accurate instruments. Although such a system was not established in his lifetime, many government agencies soon began collecting and compiling observations. During the War of 1812, the surgeon general of the army, James Tilton, ordered the physicians under his command to "keep a diary of the weather" and to file detailed reports on the effects of the climate on the health of the troops. This was because more soldiers were falling ill in camp than were being injured in military engagements. The U.S. Army Medical Department continued its system of taking meteorological measurements at army posts across the country until 1874, in part to document potential changes in the climate. Other early governmental systems included the General Land Office (1817–1821), interested primarily in settlement west of the Appalachian Mountains, and academies in the state of New York (1825–1850), where students collected climatic and phenological statistics. In the 1850s, the U.S. Navy compiled wind and weather charts for the oceans under the direction of Matthew Fontaine Maury.

Under the direction of Joseph Henry, the Smithsonian Institution served as a national center to advance and coordinate meteorological research. The institution conducted storm studies, experimented with telegraphic weather prediction, and collected climate statistics. It also served as a clearinghouse for cooperative observations taken by the navy, the army topographical engineers, the Patent Office, the Coast Survey, the Department of Agriculture, and the government of Canada. Projects completed with Smithsonian data included Climatology of the United States (1857) by Lorin Blodget, Winds of the Globe (1875) by James Henry Coffin, and theoretical studies of the general circulation of the Earth's atmosphere by William Ferrel.

In 1858, Ferrel announced a new theory of fluid mechanics that explained both meridional (E-W) and zonal (N-S) wind flows on the rotating Earth. He wrote equations of motion that accounted for most of the observed features of the general circulation: three vertical circulation cells instead of just one traditional "Hadley cell," high-velocity westerly winds in midlatitudes in both hemispheres, easterly trade winds in the tropics, and low pressure with easterly winds near the poles. Later commentators referred to Ferrel's theory as the "principia meteorologica" because of its fundamental implications for subsequent studies of climate dynamics.

In 1870, Congress established the first national weather service and placed it under the auspices of the Army Signal Office. Colonel Albert J. Myer became the first director of a well-funded national storm warning system employing the nation's telegraphy circuits "for the benefit of commerce and agriculture." In addition to providing daily reports of current conditions and "probabilities" for the next day's weather, the Signal Office collected official climate statistics for the nation. By 1891 the U.S. Weather Bureau had been established in the Department of Agriculture, where it remained until 1940, when it was transferred to the Department of Commerce.

Climate Change in the Nineteenth Century

In 1844, Samuel Forry analyzed data gathered from more than sixty army medical officers and concluded (a) climates are stable and no accurate the rmometrical observations warrant the conclusion of climatic change, (b) climates can be changed by human activity, but (c) these effects are extremely subordinate to physical geography. Elias Loomis studied the temperature of New Haven, Connecticut, and Charles A. Schott constructed national maps of temperature and rainfall. Neither scientist found evidence that humans were changing the climate. Cleveland Abbe, the chief scientist with the National Weather Service, agreed that the old debates about climate change had finally been settled. In an article entitled "Is Our Climate Changing?" published in Forum in February 1889, Abbe defined the climate as "the average about which the temporary conditions permanently oscillate; it assumes and implies permanence."

As the debate over climate change caused by human activities was winding down in the mid-nineteenth century, the discovery that the earth had experienced ice ages produced a plethora of complex but highly speculative theories of climatic change involving astronomical, physical, geological, and paleontological factors. The leading American involved in these discoveries was the prominent glacial geologist T. C. Chamberlin, whose interdisciplinary work on the geological agency of the atmosphere and the effect of carbon dioxide on climate led him to propose a new theory of the formation of the earth and the solar system.

Regional Climates and Identities

Many regions of the United States experience distinctive climatic phenomena. New England, the Appalachian Highlands, and the upper Mississippi Valley have rigorous winters with snow covering the ground, often for several months. The East Coast has a relatively mild climate due to the proximity of the Atlantic Ocean, but these areas are susceptible to land-falling Atlantic hurricanes and winter "nor'easters." The Deep South has hot summers and mild winters with high humidity because of the proximity of the warm waters of the Caribbean and the Gulf of Mexico; on average this area has the most thunderstorms. The heartland experiences the most violent tornadoes, while the high Plains have the most hailstorms. Monsoonal flows from Mexico water the desert Southwest, while California is susceptible to drying "Santa Anna" winds that can exacerbate wildfires. As scientists have come to realize, all regions of the country may be affected by the El Niño Southern Oscillation of the Pacific Ocean.

It would be foolish to argue that such climatic differences "determined" social relations in these regions, just as it would be futile to argue that the environment made little or no difference to people's lives. It is more productive to ask how the flux of economic and social activities over time changed human relationships with nature in sometimes subtle but often dramatic ways. Horse-drawn sleighs were traditionally safe, enjoyable, and often productive means of winter transportation, yet the widespread use of the automobile transformed snow from a transportation resource into a hazard. Pioneers facing the onset of winter and the possibility of crop failure due to frosts believed that warmer weather was better weather, while contemporary city dwellers in urban heat islands find the weather unbearably hot. Air conditioning undoubtedly stimulated the growth of the Sun Belt, while access to freshwater resources may determine the region's future. In general, social and technological changes and changes in scientific understanding of climate have occurred at much faster rates than have physical changes in the climate system.

Settlers seeking to relocate west of the Appalachian Mountains usually headed due west. They assumed that the climatic zone they were familiar with followed parallels of latitude. Generally, this is not the case, since agricultural hardiness zones gradually slope from northeast to southwest. Thus, for example, settlers from Connecticut established the Western Reserve in Ohio. Further west across the Mississippi River lay the semiarid, treeless prairies that were originally called the "Great American Desert." While farmers on the northern and eastern margins of this area, where annual rainfall totals twenty inches or more, had considerable success, precipitation decreases dramatically to the south and west, attaining true desert conditions in New Mexico and Arizona. The Homestead Act of 1862 encouraged farmers ever westward into marginal lands that were fertile only when it rained. Promoters even resorted to the dubious argument that agriculture somehow increases rainfall, or "rain follows the plow." A succession of drought years could devastate farms, however, as was the case in the decade-long Dust Bowl of the 1930s in the southern Great Plains.

Climate Change in the Twentieth Century

By 1900 most of the chief theories of climate change had been proposed if not yet fully explored: changes in solar output; changes in the earth's orbital geometry; changes in terrestrial geography, including the form and height of continents and the circulation of the oceans; and changes in atmospheric transparency and composition, in part due to human activities. During the International Geophysical Year (1957–1958), Harry Wexler of the U.S. Weather Bureau succeeded in establishing a series of accurate measurements of carbon dioxide. After 1958 these measurements were accurately and faithfully taken at the summit of Mauna Loa volcano in Hawaii by Charles David Keeling. Subsequently, many more international baseline stations have been established. The Keeling curve, the famous saw-toothed curve of rising carbon dioxide concentrations, became the environmental icon of the twentieth century.

In the 1950s, Gilbert Plass developed a computer model of infrared radiative transfer in support of his re-search on carbondioxide and climate. Several years later, in the interest of national security, a climate model known as Nile Blue was developed by the Advanced Research Projects Administration (ARPA) in the Department of Defense. It was hoped that this model could be used to test the sensitivity of the climate to major perturbations, including Soviet tinkering or a major environmental war. In 1967, Syukuro Manabe and Richard T. Wetherald developed a computerized climate model that included the effects of both radiation and convection to calculate temperature as a function of latitude. It predicted a mean warming of 2.3 degrees Celsius for a doubling of carbon dioxide. Two years later, Manabe and Kirk Bryan added basic oceanic features to the model.

The rise of the environmental movement in the early 1970s generated interest in global environmental problems, including climate change. In 1971, when some meteorologists were looking into the possibility of a widespread global cooling, a report from the Study of Man's Impact on Climate conducted at the Massachusetts Institute of Technology returned the focus to carbon dioxide emissions, calling them the largest single anthropogenic change that may influence the climate in the foreseeable future. During this period, anthropogenic effects on climate were called "inadvertent" climate modification. Several other regional and global pollution issues also emerged in the 1970s, including acid deposition and possible damage to the stratosphere by ozone-depleting chemicals and by the exhaust gases of a fleet of supersonic transport planes.

In the 1980s, scientists debated the possibility of a "nuclear winter" caused by an all-out nuclear exchange. Discovery of depleted levels of ozone over Antarctica in 1985 led to the international Montreal Protocol on Substances that Deplete the Ozone Layer, signed in 1987. In 1988 the scientist James Hansen of the National Aeronautics and Space Administration announced to Congress and the world, "Global warming has begun." He went on to report that, at least to his satisfaction, he had seen the "signal" in the climate noise and that the earth was destined for global warming, perhaps in the form of a runaway greenhouse effect. Hansen later revised his remarks, but his statement remained the starting point of widespread concerns over global warming. That same year the Intergovernmental Panel on Climate Change was formed as a joint program of the United Nations Environmental Program, the World Meteorological Organization, and the International Congress of Scientific Unions. It has a mandate to prepare regular assessments of what is known and what should be done about anthropogenic climate change.

The 1992 United Nations Conference on Environment and Development (the Earth Summit) in Rio de Janeiro produced the Framework Convention on Climate Change (FCCC), which calls for a stabilization of atmospheric carbon dioxide concentrations at a level that would prevent human-induced changes in the global climate. The 1997 Kyoto Protocol, calling for legally binding greenhouse gas emission targets for all developed countries, remained a contentious issue in the early twenty-first century. These conventions and protocols represent geopolitical interventions in the climate system. Many more policies were initiated. Economics also began to play a role, as taxes and incentives were put in place to reduce unwanted emissions. Meanwhile, green social engineers attempted to convince the general public to live sustainably, while "geoengineers" hold in reserve massive technical fixes for the climate system. Notably, health issues related to possible climate change returned as policy issues.

Conclusion

The climate issues that puzzled colonists and early Americans were eventually resolved by government-supported scientists who compiled climate statistics for the continent. Changes in human-climate relations were typically caused not by climate change but by people migrating to new regions or by changes in social relations or technology. Anolder medical geography of "airs, waters, and places" was replaced by the germ theory of disease. Yet as Americans gained control of their microclimatic environments through irrigation, central heating, and air conditioning, they began to lose control of the damage they inflicted on the environment, for example, by excessive burning of fossil fuels. In the second half of the twentieth century, new reasons for climate apprehension emerged in the form of local, regional, and global threats to the atmosphere and to human health. By the dawn of the twenty-first century, the social aspects of the climate had grown to encompass scientific, economic, governmental, and diplomatic initiatives regarding the health and future of the planet.

Bibliography

Fleming, James Rodger. Meteorology in America, 1800–1870. Baltimore: Johns Hopkins University Press, 1990.

———. Historical Perspectives on Climate Change and Culture. New York: Oxford University Press, 1998.

Fleming, James Rodger, ed. Historical Essays on Meteorology, 1919–1995. Boston: American Meteorological Society, 1996.

Kupperman, Karen Ordahl. "The Puzzle of the American Climate in the Early Colonial Period." American Historical Re-view 87 (1982): 1262–1289.

Ludlum, David M. The American Weather Book. Boston: Houghton Mifflin, 1982.

Mergen, Bernard. Snow in America. Washington, D.C.: Smithsonian Institution Press, 1997.

Meyer, William B. Americans and Their Weather. New York: Oxford University Press, 2000.

—James Fleming

There are five climates in Russia. The Polar climate hugs the Arctic coast and yields a 60-day growing season, with July and August averaging temperatures over freezing. Tundra vegetation prevails. South of the tundra, blanketing two-thirds of Russia, is the Subarctic climate with its brief cool summers and harsh cold, mostly dry, winters. With a growing season of sixty to ninety days, the dominant vegetation is taiga (northern coniferous forest), 90 percent of which is underlain by permafrost. In European Russia and Western Siberia, the Subarctic climate merges southward with the Humid Continental Warm-to-Cool Summer climate. Here the winters become less harsh, although much snowier, and the summers become longer and warmer. Growing seasons reach 90 to 120 days, and the vegetation is a temperate mixed forest that joins the broadleaf forests and grasslands to the south. Along the Lower Volga and in the North Caucasus, the climate becomes sub-humid. Here summers become equal to winters, a Semiarid Continental climate prevails, the growing season reaches 120 to 160 days, and grassland, or steppe, vegetation dominates. Particular to Russia's "bread-basket," a terrain with rich black loams, this climate suffers from insufficient precipitation. A tiny strip of Arid Continental climate fringes the Russian shoreline of the Caspian Sea. With hot, dry summers and rather cold, shorter winters, this climate yields a 160- to 200-day growing season. A true desert, it reflects a severe soil-moisture deficit.

Russia's massive landmass, northerly location, and flat-to-rolling terrain dramatically influence these climates. Because three-fourths of Russia is more than 250 miles (400 kilometers) away from a largely frozen sea, the climates are continental, not maritime. Continental climates exhibit wide ranges of temperature (the difference between the warmest and coldest monthly averages) and low average annual precipitation that peaks in summer instead of spring. Climatic harshness increases from west to east as the moderating influence of the warm North Atlantic Ocean decreases. St. Petersburg on the Gulf of Finland has a 45° F (25° C) difference between the July and January mean temperatures and 19 inches (48 centimeters) of annual precipitation. Yakutsk in Eastern Siberia contrasts with a 112° F (65° C) range of temperature and only 4 inches (10 centimeters) of precipitation.

Russia's high-latitude position enhances continentality. Nine-tenths of the country is north of 50° N Latitude. Moscow is in the latitude of Edmonton, Alberta; St. Petersburg equates with Anchorage, Alaska. Russia thus resembles Canada in climate more than it does the United States. High-latitude countries like Russia and Canada suffer low-angle (less-intense) sunlight and short growing seasons that range from 60 days in the Arctic to 200 days along the Caspian shore.

Low relief also augments the negative effects on Russia's climates. Three-fourths of Russia's terrain lies at elevations lower than 1,500 feet (450 meters) above sea level. This further diminishes the opportunities for rain and snow because there is less friction to cause orographic lifting. The country's open western border, uninterrupted except for the low Ural Mountains, permits Atlantic winds and air masses to penetrate as far east as the Yenisey River. In winter, these air masses bring moderation and relatively heavy snow to many parts of the European lowlands and Western Siberia. Meanwhile, a semi-permanent high-pressure cell (the Asiatic Maximum) blankets Eastern Siberia and the Russian Far East. This huge high-pressure ridge forces the Atlantic air to flow northward into the Arctic and southward against the southern mountains. Consequently, little snow or wind affects the Siberian interior in winter. The exceptions are found along the east coast (Kamchatka, the Kurils, and Maritime province).

As the Eurasian continent heats faster in summer than the oceans, the pressure cells shift position: Low pressure dominates the continents and high pressure prevails over the oceans. Moist air masses flow onto the land, bringing summer thunderstorms. The heaviest rains come later in summer from west to east, often occurring in the harvest seasons in Western Siberia. In the Russian Far East, the summer monsoon yields more than 75 percent of the region's average annual precipitation. Pacific typhoons often harry Kamchatka, the Kurils, and Sakhalin Island.

Winter temperatures plunge from west to east. Along Moscow's 55th parallel, average January temperatures fall from a high of 22° F ( - 6° C) in Kaliningrad to 14° F ( - 10° C) in the capital to 7° F ( - 14° C) in Kazan to - 6° F ( - 20° C) in Tomsk. Along the same latitude in the Russian Far East, the temperatures reach low averages of - 29° F ( - 35° C). Northeast Siberia experiences the lowest average winter temperatures outside of Antarctica: - 50° F ( - 45° C), with one-time minima of - 90° F ( - 69° C).

In July, the averages cool with higher latitudes. Thus, the Caspian desert experiences averages of near 80° F (25° C), whereas the Arctic tundra records means of 40° F (5° C). Moscow averages 65° F (19°C) in July.

Bibliography

Borisov, A. A. (1965). Climates of the USSR. Chicago: Aldine Publishing Co.

Lydolph, Paul E. (1977). Climates of the USSR: World Survey of Climatology. Amsterdam: Elsevier.

Mote, Victor L. (1994). An Industrial Atlas of the Soviet Successor States. Houston, TX: Industrial Information Resources.

—VICTOR L. MOTE

Middle Eastern climatic conditions vary greatly, depending on the season and the geography.

The Middle East and North Africa are perceived as both homogeneous and intensely arid, but the region is best characterized by its climatic variation. Although the hot arid, or desert, climate predominates in the region, the well-watered highlands of Turkey and the mountains of Iran and Ethiopia are important as sources of the region's major rivers. Climatic variation finds further expression in the temperature regimes of the northern and southern parts of the area. Average July maxima for inland
locations near 30° north latitude are as high as 108°F (42°C), while summer maximum temperatures in northern locations such as Ankara, Turkey, do not exceed 86°F (30°C). Black Sea coastal stations' (e.g., Trabzon, Turkey) average summer maxima may be as low as 79°F (26°C). January average minimum temperatures fall to 50°F (10°C) in Aswan, but reach 10°F ( - 12.5°C) in Erzurum on the Anatolian plateau.

Desert conditions are primarily the result of the subtropical zone of high pressure that coincides with 30° north latitude. In this area, cold, subsiding air warms as it approaches the earth, thus increasing its ability to hold moisture. This results in extreme evaporation from all surfaces, and under such conditions, very little rain falls. During the summer solstice, the sun is directly overhead at 23° 30′ at north latitude (e.g., at Aswan, Egypt). Annual periods of high sun in combination with clear skies through much of the year allow intense solar radiation with subsequent extreme evapotranspiration demands.

Evapotranspiration refers to the water needed by vegetation to withstand the energy of incoming solar radiation. This is accomplished through the mechanism of heat transfer by means of evaporation from inert surfaces and transpiration from stomata (pores) on leaf surfaces. Total demands made upon an individual plant are termed potential evapotranspiration (PE). Actual evapotranspi-ration (AE) is the amount of water actually available and used by the plant and reflects climatic conditions rather than optimal plant requirements. The difference between PE and AE defines the degree of aridity or drought and also the amount of irrigation water that would have to be applied for such vegetation to survive.

In the deserts of North Africa and Southwest Africa, total annual precipitation is between 2 inches (50 mm) and 14 inches (350 mm). The area from Aden to Baghdad receives from less than 2 inches (50 mm) annually to about 6 inches (150 mm). More than 39 inches (1 m) of water would be required in those places to sustain rain-fed agriculture. Under such conditions, sparse natural vegetation allows animals some seasonal grazing at best. Hyperarid areas, which seldom if ever receive rain, have no vegetation at all. Rainfall variability within the area of desert climate exceeds 40 percent, reducing to 20 percent on the moist margins of the semiarid zone, which forms a transition between the true desert to the south and the more humid areas farther north.

Precipitation on the semiarid margins of Middle Eastern deserts ranges from 14 inches (350 mm) to 30 inches (750 mm) annually. Dry farming of grains employing alternate years of fallow can be carried out with 16 inches (400 mm) or more of rain. It should be remembered that, while rainfall variability is greatest in the desert, this also means that aridity there has high predictability. Thus, the semiarid transition between regions of predictable aridity and predictable rainfall is one where rain-fed agriculture is possible but has a high chance of failure. This is biblical country - years of plenty followed by years of famine - and one to which pastoral nomadism was a practical adaptation.

The Black Sea coast of Turkey receives from 78 inches (2,000 mm) to 101 inches (2,600 mm) per year, although the transition from the windward, watered side of the Pontic range to the leeward, dry side can be very abrupt due to the topography. The Mediterranean climate, which is limited to a narrow coastal strip reaching from Gaza to Istanbul and from Tunis in the west to the Atlantic, is marked by mild winters with ample rain and long, hot summers when Sahara-like conditions prevail.

Precipitation results from three different processes. Orographic precipitation occurs on the Pontic and Taurus mountains of Turkey; the Elburz and Zagros mountains of Iran; the peaks of Lebanon and the hills of Israel, the West Bank, and Jordan; the highlands of Ethiopia; and the Atlas and Anti-Atlas mountains of northwest Africa. Such precipitation occurs as warm, moisture-bearing winds are forced to higher elevations over the mountains. When the air cools, it loses its ability to hold moisture, and rain or snow falls on the wind-ward sides of those ranges.

The Anatolian plateau and the steppes of northern Syria experience small quantities of rain in the form of convectional summer showers from thunderstorms. Equatorial convectional rains provide the waters of the White Nile.

A third cause of precipitation, particularly in the wintertime, is the passage of frontal systems from west to east across the region bringing alternating high and low pressure cells with associated cold, clear, or moist warm air masses. Frontal systems are propelled eastward by the subtropical jet stream, the position of which varies latitudinally by as much as 15° from a winter position in the north to its summer position in the south. Summer months find the path of the jet stream located from central Turkey northeastward to central Asia. Six months later the jet stream is at its maximum along a path traced across the Gulf of Suez to the head of the Gulf of Aqaba and beyond. This shift accounts for the changes in temperature and precipitation noted above.

Surface winds in the Middle East have distinctive qualities and have received local names famous throughout the region. The cold northern wind blowing from the Anatolian plateau to the southern Turkish shore in the winter is the Poyraz (derived from the Greek: bora, i.e., north); the warm on-shore wind in the same location is known as the meltem. Searing desert winds are infamous: The Egyptian khamsin, which blows in from the desert, is matched by the ghibli in Libya and the simoon in Iran.

Bibliography

Beaumont, Peter; Blake, Gerald H.; and Wagstaff, J. Malcolm. The Middle East: A Geographical Study, 2d edition. New York: Halsted Press, 1988.

Blake, Gerald; Dewdney, John; and Mitchell, Jonathan. The Cambridge Atlas of the Middle East and North Africa. Cambridge, U.K., and New York: Cambridge University Press, 1987.

Goudie, Andrew, and Wilkinson, Jon. The Warm Desert Environment. Cambridge, U.K., and New York: Cambridge University Press, 1977.

Grigg, David. The Harsh Lands: A Study in Agricultural Development. London: Macmillan; New York: St. Martin's, 1970.

— JOHN F. KOLARS

A region's usual weather patterns. The climate at any point on Earth is determined by things such as the general movement of the atmosphere, the proximity of the oceans, and the altitude of the location.

The total environmental effect of ambient temperature, barometric pressure, radiation, oxygen concentration, water precipitation, humidity, wind speed, wind direction and sunlight hours or cloud cover. Called also weather.

• c. classes — includes tropical, semitropical, desert, arid, semiarid, temperate, subarctic, arctic, polar.
• c. envelope — the range of climatic variation in which a species can persist in the face of competitors, predators and disease.
• c. impact — includes overall statements of total effect of climate such as wind-chill index, temperature–humidity index, effective temperature.

For other uses, see Climate (disambiguation).

Worldwide climate classifications

Climate encompasses the statistics of temperature, humidity, atmospheric pressure, wind, rainfall, atmospheric particle count and numerous other meteorological elements in a given region over long periods of time. Climate can be contrasted to weather, which is the present condition of these same elements over periods up to two weeks.

The climate of a location is affected by its latitude, terrain, altitude, ice or snow cover, as well as nearby water bodies and their currents. Climates can be classified according to the average and typical ranges of different variables, most commonly temperature and rainfall. The most commonly used classification scheme is the one originally developed by Wladimir Köppen. The Thornthwaite system,^[1] in use since 1948, incorporates evapotranspiration in addition to temperature and precipitation information and is used in studying animal species diversity and potential impacts of climate changes. The Bergeron and Spatial Synoptic Classification systems focus on the origin of air masses defining the climate for certain areas.

Paleoclimatology is the study and description of ancient climates. Since direct observations of climate are not available before the 19th century, paleoclimates are inferred from proxy variables that include non-biotic evidence such as sediments found in lake beds and ice cores, and biotic evidence such as tree rings and coral. Climate models are mathematical models of past, present and future climates.

Contents 1 Definition 2 Climate classification 2.1 Bergeron and Spatial Synoptic 2.2 Köppen 2.3 Thornthwaite 3 Record 3.1 Modern 3.2 Paleoclimatology 4 Climate change 4.1 Climate models 5 See also 6 References 7 External links

Definition

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Climate(from Ancient Greek klima, meaning inclination) is commonly defined as the weather averaged over a long period of time.^[2] The standard averaging period is 30 years,^[3] but other periods may be used depending on the purpose. Climate also includes statistics other than the average, such as the magnitudes of day-to-day or year-to-year variations. The Intergovernmental Panel on Climate Change (IPCC) glossary definition is:

Climate in a narrow sense is usually defined as the "average weather," or more rigorously, as the statistical description in terms of the mean and variability of relevant quantities over a period of time ranging from months to thousands or millions of years. The classical period is 30 years, as defined by the World Meteorological Organization (WMO). These quantities are most often surface variables such as temperature, precipitation, and wind. Climate in a wider sense is the state, including a statistical description, of the climate system.^[4]

The difference between climate and weather is usefully summarized by the popular phrase "Climate is what you expect, weather is what you get."^[5] Over historical time spans there are a number of nearly constant variables that determine climate, including latitude, altitude, proportion of land to water, and proximity to oceans and mountains. These change only over periods of millions of years due to processes such as plate tectonics. Other climate determinants are more dynamic: for example, the thermohaline circulation of the ocean leads to a 5 °C (9 °F) warming of the northern Atlantic ocean compared to other ocean basins.^[6] Other ocean currents redistribute heat between land and water on a more regional scale. The density and type of vegetation coverage affects solar heat absorption,^[7] water retention, and rainfall on a regional level. Alterations in the quantity of atmospheric greenhouse gases determines the amount of solar energy retained by the planet, leading to global warming or global cooling. The variables which determine climate are numerous and the interactions complex, but there is general agreement that the broad outlines are understood, at least insofar as the determinants of historical climate change are concerned.^[8]

Climate classification

There are several ways to classify climates into similar regimes. Originally, climes were defined in Ancient Greece to describe the weather depending upon a location's latitude. Modern climate classification methods can be broadly divided into genetic methods, which focus on the causes of climate, and empiric methods, which focus on the effects of climate. Examples of genetic classification include methods based on the relative frequency of different air mass types or locations within synoptic weather disturbances. Examples of empiric classifications include climate zones defined by plant hardiness,^[9] evapotranspiration,^[10] or more generally the Köppen climate classification which was originally designed to identify the climates associated with certain biomes. A common shortcoming of these classification schemes is that they produce distinct boundaries between the zones they define, rather than the gradual transition of climate properties more common in nature.

Bergeron and Spatial Synoptic

Source regions of global air masses

Main article: Air mass

The most generic classification is that involving the concept of air masses. The Bergeron classification is the most widely accepted form of air mass classification. Air mass classification involves three letters. The first letter describes its moisture properties, with c used for continental air masses (dry) and m for maritime air masses (moist). The second letter describes the thermal characteristic of its source region: T for tropical, P for polar, A for Arctic or Antarctic, M for monsoon, E for equatorial, and S for superior air (dry air formed by significant downward motion in the atmosphere). The third letter is used to designate the stability of the atmosphere. If the air mass is colder than the ground below it, it is labeled k. If the air mass is warmer than the ground below it, it is labeled w.^[11] While air mass identification was originally used in weather forecasting during the 1950s, climatologists began to establish synoptic climatologies based on this idea in 1973.^[12]

Based upon the Bergeron classification scheme is the Spatial Synoptic Classification system (SSC). There are six categories within the SSC scheme: Dry Polar (similar to continental polar), Dry Moderate (similar to maritime superior), Dry Tropical (similar to continental tropical), Moist Polar (similar to maritime polar), Moist Moderate (a hybrid between maritime polar and maritime tropical), and Moist Tropical (similar to maritime tropical, maritime monsoon, or maritime equatorial).^[13]

Köppen

Monthly average surface temperatures from 1961–1990. This is an example of how climate varies with location and season

Main article: Köppen climate classification

The Köppen classification depends on average monthly values of temperature and precipitation. The most commonly used form of the Köppen classification has five primary types labeled A through E. Specifically, the primary types are A, tropical; B, dry; C, mild mid-latitude; D, cold mid-latitude; and E, polar. The five primary classifications can be further divided into secondary classifications such as rain forest, monsoon, tropical savanna, humid subtropical, humid continental, oceanic climate, Mediterranean climate, steppe, subarctic climate, tundra, polar ice cap, and desert.

Rain forests are characterized by high rainfall, with definitions setting minimum normal annual rainfall between 1,750 millimetres (69 in) and 2,000 millimetres (79 in). Mean monthly temperatures exceed 18 °C (64 °F) during all months of the year.^[14]

A monsoon is a seasonal prevailing wind which lasts for several months, ushering in a region's rainy season.^[15] Regions within North America, South America. Sub-Saharan Africa, Australia and East Asia are monsoon regimes.^[16]

A tropical savanna is a grassland biome located in semi-arid to semi-humid climate regions of subtropical and tropical latitudes, with average temperatures remain at or above 18 °C (64 °F) year round and rainfall between 750 millimetres (30 in) and 1,270 millimetres (50 in) a year. They are widespread on Africa, and are also found in India, the northern parts of South America, Malaysia, and Australia.^[17]

The humid subtropical climate zone where winter rainfall (and sometimes snowfall) is associated with large storms that the westerlies steer from west to east. Most summer rainfall occurs during thunderstorms and from occasional tropical cyclones.^[18] Humid subtropical climates lie on the east side continents, roughly between latitudes 20° and 40° degrees away from the equator.^[19]

Humid continental climate worldwide

A humid continental climate is marked by variable weather patterns and a large seasonal temperature variance. Places with a hottest monthly temperature above 10 °C (50 °F) and a coldest month temperature below −3 °C (26.6 °F) and which do not meet the criteria for an arid climate, are classified as continental.^[20]

An oceanic climate is typically found along the west coasts at the middle latitudes of all the world's continents, and in southeastern Australia, and is accompanied by plentiful precipitation year round.^[21]

The Mediterranean climate regime resembles the climate of the lands in the Mediterranean Basin, parts of western North America, parts of Western and South Australia, in southwestern South Africa and in parts of central Chile. The climate is characterized by hot, dry summers and cool, wet winters.^[22]

A steppe is a dry grassland with an annual temperature range in the summer of up to 40 °C (104 °F) and during the winter down to −40 °C (−40.0 °F).^[23]

A subarctic climate has little precipitation,^[24] and monthly temperatures which are above 10 °C (50 °F) for one to three months of the year, with continuous permafrost due to the very cold winters. Winters within subarctic climates include up to six months of temperatures averaging below 0 °C (32 °F).^[25]

Map of arctic tundra

Tundra occurs in the far Northern Hemisphere, north of the taiga belt, including vast areas of northern Russia and Canada ^[26].

A polar ice cap, or polar ice sheet, is a high-latitude region of a planet or moon that is covered in ice. Ice caps form because high-latitude regions receive less energy in the form of solar radiation from the sun than equatorial regions, resulting in lower surface temperatures.^[27]

A desert is a landscape form or region that receives very little precipitation. Deserts usually have a large diurnal and seasonal temperature range, with high daytime temperatures (in summer up to 45 °C or 113 °F), and low night-time temperatures (in winter down to 0 °C; 32 °F) due to extremely low humidity. Many deserts are formed by rain shadows, as mountains block the path of moisture and precipitation to the desert.^[28]

Thornthwaite

See also: Microthermal, Mesothermal, and Megathermal

Precipitation by month

Devised by the American climatologist and geographer C. W. Thornthwaite, this climate classification method monitors the soil water budget using the concept of evapotranspiration.^[10] It monitors the portion of total precipitation used to nourish vegetation over a certain area.^[29] It uses indices such as a humidity index and an aridity index to determine an area's moisture regime based upon its average temperature, average rainfall, and average vegetation type.^[30] The lower the value of the index is any given area, the drier the area is.

The moisture classification includes climatic classes with descriptors such as hyperhumid, humid, subhumid, subarid, semi-arid (values of -20 to -40), and arid (values below -40).^[31] Humid regions experience more precipitation than evaporation each year, while arid regions experience greater evaporation than precipitation on an annual basis. A total of 33 percent of the Earth's landmass is considered either arid of semi-arid, including southwest North America, southwest South America, most of northern and a small part of southern Africa, southwest and portions of eastern Asia, as well as much of Australia.^[32] Studies suggest that precipitation effectiveness (PE) within the Thornthwaite moisture index is overestimated in the summer and underestimated in the winter.^[33] This index can be effectively used to determine the number of herbivore and mammal species numbers within a given area.^[34] The index is also used in studies of climate change.^[33]

Thermal classifications within the Thornthwaite scheme include microthermal, mesothermal, and megathermal regimes. A microthermal climate is one of low annual mean temperatures, generally between 0 °C (32 °F) and 14 °C (57 °F) which experiences short summers and has a potential evaporation between 14 centimetres (5.5 in) and 43 centimetres (17 in).^[35] A mesothermal climate lacks persistent heat or persistent cold, with potential evaporation between 57 centimetres (22 in) and 114 centimetres (45 in).^[36] A megathermal climate is one with persistent high temperatures and abundant rainfall, with potential evaporation in excess of 114 centimetres (45 in).^[37]

Record

Modern

Instrumental temperature record of the last 150 years

Details of the modern climate record are known through the taking of measurements from such weather instruments as thermometers, barometers, and anemometers during the past few centuries. The instruments used to study weather conditions over the modern time scale, their known error, their immediate environment, and their exposure have changed over the years, which must be considered when studying the climate of centuries past.^[38]

Paleoclimatology

Main article: Paleoclimatology

Paleoclimatology is the study of past climate over a great period of the Earth's history. It uses evidence from ice sheets, tree rings, sediments, coral, and rocks to determine the past state of the climate. It demonstrates periods of stability and periods of change and can indicate whether changes follow patterns such as regular cycles.^[39]

Climate change

Variations in CO₂, temperature and dust from the Vostok ice core over the past 450,000 years

See also: Climate change, Global warming, temperature record, and attribution of recent climate change

Climate change is the variation in global or regional climates over time. It reflects changes in the variability or average state of the atmosphere over time scales ranging from decades to millions of years. These changes can be caused by processes internal to the Earth, external forces (e.g. variations in sunlight intensity) or, more recently, human activities.^[40]

In recent usage, especially in the context of environmental policy, the term "climate change" often refers only to changes in modern climate, including the rise in average surface temperature known as global warming. In some cases, the term is also used with a presumption of human causation, as in the United Nations Framework Convention on Climate Change (UNFCCC). The UNFCCC uses "climate variability" for non-human caused variations.^[41]

Earth has undergone periodic climate shifts in the past, including four major ice ages. These consisting of glacial periods where conditions are colder than normal, separated by interglacial periods. The accumulation of snow and ice during a glacial period increases the surface albedo, reflecting more of the Sun's energy into space and maintaining a lower atmospheric temperature. Increases in greenhouse gases, such as by volcanic activity, can increase the global temperature and produce an interglacial. Suggested causes of ice age periods include the positions of the continents, variations in the Earth's orbit, changes in the solar output, and vulcanism.^[42]

Climate models

See also: Climate models and Climatology

Climate models use quantitative methods to simulate the interactions of the atmosphere,^[43] oceans, land surface and ice. They are used for a variety of purposes from study of the dynamics of the weather and climate system to projections of future climate. All climate models balance, or very nearly balance, incoming energy as short wave (including visible) electromagnetic radiation to the earth with outgoing energy as long wave (infrared) electromagnetic radiation from the earth. Any imbalance results in a change in the average temperature of the earth.

The most talked-about models of recent years have been those used to infer the consequences of increasing greenhouse gases in the atmosphere, primarily carbon dioxide (see greenhouse gas). These models predict an upward trend in the global mean surface temperature, with the most rapid increase in temperature being projected for the higher latitudes of the Northern Hemisphere.

Models can range from relatively simple to quite complex:

• A simple radiant heat transfer model that treats the earth as a single point and averages outgoing energy
• this can be expanded vertically (radiative-convective models), or horizontally
• finally, (coupled) atmosphere–ocean–sea ice global climate models discretise and solve the full equations for mass and energy transfer and radiant exchange.^[44]

See also

Weather portal

• Atmosphere
• Climate Prediction Center
• Ecosystem
• Effect of sun angle on climate
• Greenhouse effect
• Microclimate
• National Climatic Data Center
• Solar variation
• Temperature extreme
• Weather
• Outline of meteorology

References

1. ^ C. W. Thornthwaite, "An Approach Toward a Rational Classification of Climate", Geographical Review, 38:55-94, 1948
2. ^ "Climate". Glossary of Meteorology. American Meteorological Society. http://amsglossary.allenpress.com/glossary/search?id=climate1. Retrieved 2008-05-14. 
3. ^ "Climate averages". Met Office. http://www.metoffice.gov.uk/climate/uk/averages. Retrieved 2008-05-17. 
4. ^ Intergovernmental Panel on Climate Change. Appendix I: Glossary. Retrieved on 2007-06-01.
5. ^ National Weather Service Office Tucson, Arizona. Main page. Retrieved on 2007-06-01.
6. ^ Stefan Rahmstorf. The Thermohaline Ocean Circulation: A Brief Fact Sheet. Retrieved on 2008-05-02.
7. ^ Gertjan de Werk and Karel Mulder. Heat Absorption Cooling For Sustainable Air Conditioning of Households. Retrieved on 2008-05-02.
8. ^ Ledley, T.S.; Sundquist, E.T.; Schwartz, S.E.; Hall, D.K.; Fellows, J.D.; Killeen, T.L. (1999). "Climate change and greenhouse gases". EOS 80 (39): 453. doi:10.1029/99EO00325. http://www.agu.org/eos_elec/99148e.html. Retrieved 2008-05-17. 
9. ^ United States National Arboretum. USDA Plant Hardiness Zone Map. Retrieved on 2008-03-09
10. ^ ^{a b} "Thornethwaite Moisture Index". Glossary of Meteorology. American Meteorological Society. http://amsglossary.allenpress.com/glossary/search?p=1&query=Thornthwaite&submit=Search. Retrieved 2008-05-21. 
11. ^ "Airmass Classification". Glossary of Meteorology. American Meteorological Society. http://amsglossary.allenpress.com/glossary/search?id=airmass-classification1. Retrieved 2008-05-22. 
12. ^ Schwartz, M.D. (1995). "Detecting Structural Climate Change: An Air Mass-Based Approach in the North Central United States, 1958-1992". Annals of the Association of American Geographers 85 (3): 553–568. doi:10.1111/j.1467-8306.1995.tb01812.x. 
13. ^ Robert E. Davis, L. Sitka, D. M. Hondula, S. Gawtry, D. Knight, T. Lee, and J. Stenger. J1.10 A preliminary back-trajectory and air mass climatology for the Shenandoah Valley (Formerly J3.16 for Applied Climatology). Retrieved on 2008-05-21.
14. ^ Susan Woodward. Tropical Broadleaf Evergreen Forest: The Rainforest. Retrieved on 2008-03-14.
15. ^ "Monsoon". Glossary of Meteorology. American Meteorological Society. http://amsglossary.allenpress.com/glossary/search?p=1&query=monsoon. Retrieved 2008-05-14. 
16. ^ International Committee of the Third Workshop on Monsoons. The Global Monsoon System: Research and Forecast. Retrieved on 2008-03-16.
17. ^ Susan Woodward. Tropical Savannas. Retrieved on 2008-03-16.
18. ^ "Humid subtropical climate". Encyclopædia Britannica. Encyclopædia Britannica Online. 2008. http://www.britannica.com/eb/article-53358/climate. Retrieved 2008-05-14. 
19. ^ Michael Ritter. Humid Subtropical Climate. Retrieved on 2008-03-16.
20. ^ Peel, M. C. and Finlayson, B. L. and McMahon, T. A. (2007). "Updated world map of the Köppen-Geiger climate classification". Hydrol. Earth Syst. Sci. 11: 1633–1644. ISSN 1027-5606. http://www.hydrol-earth-syst-sci.net/11/1633/2007/hess-11-1633-2007.html. 
21. ^ Climate. Oceanic Climate. Retrieved on 2008-04-15.
22. ^ Michael Ritter. Mediterranean or Dry Summer Subtropical Climate. Retrieved on 2008-04-15.
23. ^ Blue Planet Biomes. Steppe Climate. Retrieved on 2008-04-15.
24. ^ Michael Ritter. Subarctic Climate. Retrieved on 2008-04-16.
25. ^ Susan Woodward. Taiga or Boreal Forest. Retrieved on 2008-06-06.
26. ^ "The Tundra Biome". The World's Biomes. http://www.ucmp.berkeley.edu/glossary/gloss5/biome/tundra.html. Retrieved 2006-03-05. 
27. ^ Michael Ritter. Ice Cap Climate. Retrieved on 2008-03-16.
28. ^ San Diego State University. Introduction to Arid Regions: A Self-Paced Tutorial. Retrieved on 2008-04-16.
29. ^ "Moisture Index". Glossary of Meteorology. American Meteorological Society. http://amsglossary.allenpress.com/glossary/search?id=moisture-index1. Retrieved 2008-05-21. 
30. ^ Eric Green. Foundations of Expansive Clay Soil. Retrieved on 2008-05-21.
31. ^ Istituto Agronomico per l'Otremare. 3 Land Resources. Retrieved on 2008-05-21.
32. ^ Fredlund, D.G.; Rahardjo, H. (1993) (pdf). Soil Mechanics for Unsaturated Soils. Wiley-Interscience. ISBN 978-0471850083. OCLC 26543184. http://www.soilvision.com/subdomains/unsaturatedsoil.com/Docs/chapter1UST.pdf. Retrieved 2008-05-21. 
33. ^ ^{a b} Gregory J. McCabe and David M. Wolock. Trends and temperature sensitivity of moisture conditions in the conterminous United States. Retrieved on 2008-05-21.
34. ^ Hawkins, B.A.; Pausas, J.G. (2004). "Does plant richness influence animal richness?: the mammals of Catalonia (NE Spain)". Diversity & Distributions 10 (4): 247–252. doi:10.1111/j.1366-9516.2004.00085.x. http://repositories.cdlib.org/cgi/viewcontent.cgi?article=1741&context=postprints. Retrieved 2008-05-21. 
35. ^ "Microthermal Climate". Glossary of Meteorology. American Meteorological Society. http://amsglossary.allenpress.com/glossary/search?id=microthermal-climate1. Retrieved 2008-05-21. 
36. ^ "Mesothermal Climate". Glossary of Meteorology. American Meteorological Society. http://amsglossary.allenpress.com/glossary/search?id=mesothermal-climate1. Retrieved 2008-05-21. 
37. ^ "Megathermal Climate". Glossary of Meteorology. American Meteorological Society. http://amsglossary.allenpress.com/glossary/search?id=megathermal-climate1. Retrieved 2008-05-21. 
38. ^ Spencer Weart. The Modern Temperature Trend. Retrieved on 2007-06-01.
39. ^ National Oceanic and Atmospheric Administration. NOAA Paleoclimatology. Retrieved on 2007-06-01.
40. ^ Arctic Climatology and Meteorology. Climate change. Retrieved on 2008-05-19.
41. ^ "Glossary". Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change. Intergovernmental Panel on Climate Change. 2001-01-20. http://www.grida.no/climate/ipcc_tar/wg1/518.htm. Retrieved 2008-05-22. 
42. ^ Illinois State Museum (2002). Ice Ages. Retrieved on 2007-05-15.
43. ^ Eric Maisonnave. Climate Variability. Retrieved on 2008-05-02.
44. ^ Climateprediction.net. Modelling the climate. Retrieved on 2008-05-02.

External links

This article's external links may not follow Wikipedia's content policies or guidelines. Please improve this article by removing excessive or inappropriate external links. (October 2009)

• The Economics of Climate-based Data & Products for Business & Society NOAA Economics
• IFAS AgClimate
• Climate Models and modeling groups
• Climate Prediction Project
• ClimateDiagrams.com Provides climate diagrams for more than 3000 weather stations and different climate periods from all over the world. Users can also create their own diagrams with their own data.
• WorldClimate
• ESPERE Climate Encyclopaedia
• Climate index and mode information regarding the Arctic
• A current view of the Bering Sea Ecosystem and Climate
• Climate: Data and charts for world and US locations
• MIL-HDBK-310, Global Climate Data U.S. Department of Defense Data on natural environmental starting points for engineering analyses to derive environmental design criteria.

v • d • e Meteorological data and variables General Adiabatic processes · Lapse rate · Lightning · Surface solar radiation · Surface weather analysis · Visibility · Vorticity · Wind Condensation Cloud · Cloud condensation nuclei · Fog · Precipitation · Water vapor Convection Convective available potential energy (CAPE) · Convective inhibition (CIN) · Convective instability · Convective temperature (Tc) · Helicity · Lifted index (LI) · Bulk Richardson number (BRN) Temperature Dew point (Td) · Equivalent temperature (Te) · Forest fire weather index · Haines Index · Heat index · Humidex · Humidity · Potential temperature (θ) · Equivalent potential temperature (θe) · Sea surface temperature (SST) · Wet-bulb temperature · Wet-bulb potential temperature · Wind chill Pressure Atmospheric pressure · Baroclinity · Barotropicity

v • d • e Climate types under the Köppen climate classification Class A Equatorial (Af) · Tropical monsoon (Am) · Tropical savanna (Aw, As) Class B Desert (BWh, BWk) · Semi-arid (BSh, BSk) Class C Humid subtropical (Cfa, Cwa) · Oceanic (Cfb, Cwb, Cfc) · Mediterranean (Csa, Csb) Class D Humid continental (Dfa, Dwa, Dfb, Dwb) · Subarctic (Dfc, Dwc, Dfd, Dwd) · Continental Mediterranean (Dsa, Dsb, Dsc) Class E Polar (ET, EF) · Alpine (ET/H)

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Dansk (Danish)
n. - klima, egn, stemning

idioms:

• climatic change    klimatisk forandring

Nederlands (Dutch)
klimaat(gordel), sfeer

Français (French)
n. - climat, (fig) atmosphère, (Écon, Pol) climat

idioms:

• climatic change    changement climatique

Deutsch (German)
n. - Klima

idioms:

• climatic change    Klimaschwankung

Ελληνική (Greek)
n. - (μετεωρ.) κλίμα, (μτφ.) ατμόσφαιρα, ιδιάζουσες συνθήκες

idioms:

• climatic change    κλιματολογική αλλαγή

Italiano (Italian)
clima, atmosfera

idioms:

• maritime climate    clima marittimo

Português (Portuguese)
n. - clima (m)

idioms:

• maritime climate    clima (m) marítimo

Русский (Russian)
климат, атмосфера

idioms:

• maritime climate    влажный климат

Español (Spanish)
n. - clima, ambiente, atmósfera

idioms:

• climatic change    cambio climático

Svenska (Swedish)
n. - klimat, atmosfär (bildl.)

中文（简体）(Chinese (Simplified))
气候, 思潮, 风土

idioms:

• climatic change    气候变化

中文（繁體）(Chinese (Traditional))
n. - 氣候, 思潮, 風土

idioms:

• climatic change    氣候變化

한국어 (Korean)
n. - 기후, 풍토

日本語 (Japanese)
n. - 気候, 地方, 風潮, 雰囲気

العربيه (Arabic)
‏(الاسم) مناخ, جو‏

עברית (Hebrew)
n. - ‮אקלים‬

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