Climate
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[[Image:ClimateMapWorld.png|thumb|right|350px|Worldwide climate classifications]]
'''Climate''' encompasses the temperatures, humidity, rainfall, atmospheric particle count and numerous other meteorogical factors [[weather]] in a given region over long periods of time. The climate of a location is affected by its latitude, terrain, persistent ice or snow cover, as well as nearby oceans and their currents. Climates can be [[Climate classification|classified]] using parameters such as temperature and rainfall to define specific climate types. The most commonly used classification scheme is the one originally developed by [[Wladimir Koeppen]]. The Thornthwaite system,<ref>[[C. W. Thornthwaite]], "An Approach Toward a Rational Classification of Climate", ''Geographical Review'', 38:55-94, 1948</ref> 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 change]]s. The Bergeron and [[Spatial Synoptic Classification system]]s focus on the origin of air masses defining the climate for certain areas.
[[Paleoclimatology]] is the study and description of ancient climates using information from both non-biotic factors such as sediments found in lake beds and ice cores, and biotic factors such as tree rings and coral, and can be used to extend back the temperature or rainfall information for particular locations to a time before various weather instruments were used to monitor weather conditions. [[Climate model]]s are mathematical models of past, present and future climates and can be used to describe the likely patterns of future changes.
== Definition ==
{{Weather_nav}}
Climate (from [[Ancient Greek]] ''klima'') is commonly defined as the weather averaged over a long period of time.<ref>{{cite encyclopedia | title = Climate | encyclopedia = Glossary of Meteorology | publisher = [[American Meteorological Society]] | url = http://amsglossary.allenpress.com/glossary/search?id=climate1 | accessdate = 2008-05-14 }}</ref> The standard averaging period is 30 years,<ref>{{cite web |url= http://www.metoffice.gov.uk/climate/uk/averages |title= Climate averages |accessdate=2008-05-17 |publisher= Met Office}}</ref> 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.''<ref>[[Intergovernmental Panel on Climate Change]]. [http://www.grida.no/climate/ipcc_tar/wg1/518.htm Appendix I: Glossary.] Retrieved on [[2007-06-01]].</ref>
The difference between climate and weather is usefully summarized by the popular phrase "Climate is what you expect, weather is what you get."<ref>National Weather Service Office Tucson, Arizona. [http://www.wrh.noaa.gov/twc/ Main page.] Retrieved on [[2007-06-01]].</ref> Over [[history|historical]] time spans there are a number of static variables that determine climate, including latitude, altitude, proportion of land to water, and proximity to oceans and mountains. 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.<ref>Stefan Rahmstorf. [http://www.pik-potsdam.de/~stefan/thc_fact_sheet.html The Thermohaline Ocean Circulation: A Brief Fact Sheet.] Retrieved on [[2008-05-02]].</ref> 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,<ref>Gertjan de Werk and Karel Mulder. [http://www.enhr2007rotterdam.nl/documents/W15_paper_DeWerk_Mulder.pdf Heat Absorption Cooling For Sustainable Air Conditioning of Households.] Retrieved on [[2008-05-02]].</ref> water retention, and rainfall on a regional level. Alterations in the quantity of atmospheric [[greenhouse gas]]es 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.<ref name=Ledley1999>{{cite journal | author = Ledley, T.S. | coauthors = Sundquist, E.T.; Schwartz, S.E.; Hall, D.K.; Fellows, J.D.; Killeen, T.L. | year = 1999 | title = Climate change and greenhouse gases | journal = [[Eos (journal)|EOS]] | volume = 80 | issue = 39 | pages = 453 | url = http://www.agu.org/eos_elec/99148e.html | accessdate = 2008-05-17 | doi = 10.1029/99EO00325}}</ref>
== [[Climate classification]] ==
There are several ways to classify climates into similar regimes. Originally, [[clime]]s 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,<ref>[[United States National Arboretum]]. [http://www.usna.usda.gov/Hardzone/ushzmap.html USDA Plant Hardiness Zone Map.] Retrieved on [[2008-03-09]]</ref> evapotranspiration,<ref name="thorne">{{cite encyclopedia | title = Thornethwaite Moisture Index | encyclopedia = Glossary of Meteorology | publisher = [[American Meteorological Society]] | url = http://amsglossary.allenpress.com/glossary/search?p=1&query=Thornthwaite&submit=Search | accessdate = 2008-05-21 }}</ref> air mass origin, 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 ===
[[Image:Air masses 2.jpg|thumb|250px|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.<ref>{{cite encyclopedia | title = Airmass Classification | encyclopedia = Glossary of Meteorology | publisher = [[American Meteorological Society]] | url = http://amsglossary.allenpress.com/glossary/search?id=airmass-classification1 | accessdate = 2008-05-22 }}</ref> 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.<ref name=Schwartz1995>{{cite journal | author = Schwartz, M.D. | year = 1995 | title = Detecting Structural Climate Change: An Air Mass-Based Approach in the North Central United States, 1958-1992 | journal = Annals of the Association of American Geographers | volume = 85 | issue = 3 | pages = 553–568 | doi = 10.1111/j.1467-8306.1995.tb01812.x}}</ref>
Based upon the Bergeron classification scheme is the Spatial Synoptic Classification (SSC) system. 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).<ref>Robert E. Davis, L. Sitka, D. M. Hondula, S. Gawtry, D. Knight, T. Lee, and J. Stenger. [http://ams.confex.com/ams/pdfpapers/118516.pdf 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]].</ref>
=== Köppen ===
[[Image:Annual Average Temperature Map.jpg|thumb|250px|right|Annual average surface temperatures from 1961–1990. This is an example of how climate varies with location.]]
{{Main article|Köppen climate classification}}
The Köppen classification includes climate regimes such as [[Rain forest]], [[monsoon]], [[tropical savanna]], [[humid subtropical]], [[humid continental]], [[oceanic climate]], [[Mediterranean climate]], continental [[steppe]], [[subarctic climate]], [[tundra]], [[polar ice cap]], and [[desert]].
<br />'''Rain forests''' are characterized by high [[rainfall]], with definitions setting minimum normal annual rainfall between {{convert|1750|mm|in}} and {{convert|2000|mm|in}}. Mean monthly temperatures exceed {{convert|18|C|F}} during all months of the year.<ref>Susan Woodward. [http://www.radford.edu/~swoodwar/CLASSES/GEOG235/biomes/rainforest/rainfrst.html Tropical Broadleaf Evergreen Forest: The Rainforest.] Retrieved on [[2008-03-14]].</ref>
<br />A '''monsoon''' is a seasonal prevailing wind which lasts for several months, ushering in a region's rainy season.<ref>{{cite encyclopedia | title = Monsoon | encyclopedia = Glossary of Meteorology | publisher = [[American Meteorological Society]] | url = http://amsglossary.allenpress.com/glossary/search?p=1&query=monsoon | accessdate = 2008-05-14 }}</ref> Regions such as within [[North America]], [[South America]]. [[Sub-Saharan Africa]], [[Australia]] and [[East Asian monsoon|East Asia]] to qualify as monsoon regimes.<ref>International Committee of the Third Workshop on Monsoons. [http://caos.iisc.ernet.in/faculty/bng/IWM-III-BNG_overview.pdf The Global Monsoon System: Research and Forecast.] Retrieved on [[2008-03-16]].</ref>
<br />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 {{convert|18|C|F}} year round and rainfall between {{convert|750|mm|in}} and {{convert|1270|mm|in}} a year. They are widespread on [[Africa]], and are also found in [[India]], the northern parts of [[South America]], [[Malaysia]], and [[Australia]].<ref name="SAVWOOD">Susan Woodward. [http://www.radford.edu/~swoodwar/CLASSES/GEOG235/biomes/savanna/savanna.html Tropical Savannas.] Retrieved on [[2008-03-16]].</ref>
<br />The '''humid subtropical''' climate zone where winter rainfall (and sometimes [[snowfall]]) is associated with large [[storm]]s that the [[westerlies]] steer from west to east. Most summer rainfall occurs during [[thunderstorm]]s and from occasional [[tropical cyclone]]s.<ref>{{cite encyclopedia | title = Humid subtropical climate | encyclopedia = [[Encyclopædia Britannica]] | publisher = Encyclopædia Britannica Online | date = 2008 | url = http://www.britannica.com/eb/article-53358/climate | accessdate = 2008-05-14 }}</ref> Humid subtropical climates lie on the east side continents, roughly between [[latitude]]s 20° and 40° degress away from the equator.<ref>Michael Ritter. [http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/climate_systems/humid_subtropical.html Humid Subtropical Climate.] Retrieved on [[2008-03-16]].</ref>
[[Image:Humidcontinentalworldwiderev.PNG|thumb|right|250px|[[Humid continental climate]] worldwide]]
'''Humid continental''' climate is marked by variable weather patterns and a large seasonal temperature variance. Places with a hottest monthly temperature above {{convert|10|C|F}} and a coldest month temperature below {{convert|-3|C|F}} and which do not meet the criteria for an [[arid climate]], are classified as continental.<ref name="Peel2007">{{cite journal | author=Peel, M. C. and Finlayson, B. L. and McMahon, T. A. | year=2007 | title= Updated world map of the Köppen-Geiger climate classification | journal=Hydrol. Earth Syst. Sci. | volume=11 | pages=1633–1644 | url=http://www.hydrol-earth-syst-sci.net/11/1633/2007/hess-11-1633-2007.html | issn = 1027-5606}}</ref>
<br />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.<ref>Climate. [http://www.meteorologyclimate.com/Oceanic-climate.htm Oceanic Climate.] Retrieved on [[2008-04-15]].</ref>
<br />The '''Mediterranean climate''' regime resembles the climate of the lands in the [[Mediterranean Basin]], parts of western [[North America]], parts of [[Western Australia|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.<ref>Michael Ritter. [http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/climate_systems/mediterranean.html Mediterranean or Dry Summer Subtropical Climate.] Retrieved on [[2008-04-15]].</ref>
<br />A '''steppe''' is a dry [[grassland]] with an annual temperature range in the summer of up to {{convert|40|C|F}} and during the winter down to {{convert|-40|C|F}}.<ref>Blue Planet Biomes. [http://www.blueplanetbiomes.org/steppe_climate_page.htm Steppe Climate.] Retrieved on [[2008-04-15]].</ref>
<br />A '''[[subarctic climate]]''' has little precipitation,<ref name="subritter">Michael Ritter. [http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/climate_systems/subarctic.html Subarctic Climate.] Retrieved on [[2008-04-16]].</ref> and monthly temperatures which are above {{convert|10|C|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 {{convert|0|C|F}}.<ref>Susan Woodward. [http://www.radford.edu/~swoodwar/CLASSES/GEOG235/biomes/taiga/taiga.html Taiga or Boreal Forest.] Retrieved on [[2008-06-06]].</ref>
[[Image:800px-Map-Tundra.png|thumb|right|250 px|Map of arctic tundra]]
'''Arctic tundra''' occurs in the far [[Northern Hemisphere]], north of the [[taiga]] belt, including vast areas of northern [[Russia]] and [[Canada]] <ref name="berkeley">{{cite web|title=The Tundra Biome|work=The World's Biomes|url=http://www.ucmp.berkeley.edu/glossary/gloss5/biome/tundra.html|accessdate=2006-03-05}}</ref>.
<br />A '''polar ice cap''', or polar ice sheet, is a high-[[latitude]] region of a [[planet]] or [[natural satellite|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 [[equator]]ial regions, resulting in lower [[surface temperature]]s.<ref>Michael Ritter. [http://www.uwsp.edu/geo/faculty/ritter/geog101/textbook/climate_systems/icecap.html Ice Cap Climate.] Retrieved on [[2008-03-16]].</ref>
<br />'''A desert''' is a [[landscape]] form or region that receives very little [[precipitation (meteorology)|precipitation]]. Deserts usually have a large [[Diurnal temperature variation|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 shadow]]s, as mountains block the path of moisture and precipitation to the desert.<ref>[[San Diego State University]]. [http://www-rohan.sdsu.edu/~batterso/port_arid/formation.html Introduction to Arid Regions: A Self-Paced Tutorial.] Retrieved on [[2008-04-16]].</ref>
=== Thornthwaite ===
{{See also|Microthermal|Mesothermal|Megathermal}}
This climate classification method monitors the soil water budget using the concept of evapotranspiration.<ref name="thorne">Glossary of Meteorology. [http://amsglossary.allenpress.com/glossary/search?p=1&query=Thornthwaite&submit=Search Thornethwaite Moisture Index.] Retrieved on [[2008-05-21]].</ref> It monitors the portion of total precipitation used to nourish vegetation over a certain area.<ref>{{cite encyclopedia | title = Moisture Index | encyclopedia = Glossary of Meteorology | publisher = [[American Meteorological Society]] | url = http://amsglossary.allenpress.com/glossary/search?id=moisture-index1 | accessdate = 2008-05-21 }}</ref> 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.<ref>Eric Green. [http://www.slabongrade.net/DesignSeminars/SeminarDownloads/Science_of_Expansive_Clay.pdf Foundations of Expansive Clay Soil.] Retrieved on [[2008-05-21]].</ref> 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).<ref>Istituto Agronomico per l'Otremare. [http://www.iao.florence.it/training/geomatics/Thies/Senegal_23linkedp6.htm 3 Land Resources.] Retrieved on [[2008-05-21]].</ref> 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.<ref name=Fredlund1993>{{cite book | author = Fredlund, D.G. | coauthors = Rahardjo, H. | year = 1993 | title = Soil Mechanics for Unsaturated Soils | publisher = Wiley-Interscience | url = http://www.soilvision.com/subdomains/unsaturatedsoil.com/Docs/chapter1UST.pdf | format = pdf | isbn = 978-0471850083 | accessdate = 2008-05-21}}</ref> Studies suggest that precipitation effectiveness (PE) within the Thornthwaite moisture index is overestimated in the summer and underestimated in the winter.<ref name="greg">Gregory J. McCabe and David M. Wolock. [http://www.int-res.com/articles/cr2002/20/c020p019.pdf Trends and temperature sensitivity of moisture conditions in the conterminous United States.] Retrieved on [[2008-05-21]].</ref> This index can be effectively used to determine the number of [[herbivore]] and [[mammal]] species numbers within a given area.<ref name=Hawkins2004>{{cite journal | author = Hawkins, B.A. | coauthors = Pausas, J.G. | year = 2004 | title = Does plant richness influence animal richness?: the mammals of Catalonia (NE Spain) | journal = Diversity & Distributions | volume = 10 | issue = 4 | pages = 247–252 | url = http://repositories.cdlib.org/cgi/viewcontent.cgi?article=1741&context=postprints | doi = 10.1111/j.1366-9516.2004.00085.x
| accessdate = 2008-05-21}}</ref> The index is also used in studies of climate change.<ref name="greg">Gregory J. McCabe and David M. Wolock. [http://www.int-res.com/articles/cr2002/20/c020p019.pdf Trends and temperature sensitivity of moisture conditions in the conterminous United States.] Retrieved on [[2008-05-21]].</ref>
Thermal classifications within the Thornthwaite scheme include microthermal, mesothermal, and megathermal regimes. A mircothermal climate is one of low annual mean temperatures, generally between {{convert|0|C|F}} and {{convert|14|C|F}} which experiences short summers and has a potential evaporation between {{convert|14|cm|in}} and {{convert|43|cm|in}}.<ref>{{cite encyclopedia | title = Microthermal Climate | encyclopedia = Glossary of Meteorology | publisher = [[American Meteorological Society]] | url = http://amsglossary.allenpress.com/glossary/search?id=microthermal-climate1 | accessdate = 2008-05-21 }}</ref> A mesothermal climate lacks persistent heat or persistent cold, with potential evaporation between {{convert|57|cm|in}} and {{convert|114|cm|in}}.<ref>{{cite encyclopedia | title = Mesothermal Climate | encyclopedia = Glossary of Meteorology | publisher = [[American Meteorological Society]] | url = http://amsglossary.allenpress.com/glossary/search?id=mesothermal-climate1 | accessdate = 2008-05-21 }}</ref> A megathermal climate is one with persistent high temperatures and abundant rainfall, with potential evaporation in excess of {{convert|114|cm|in}}.<ref>{{cite encyclopedia | title = Megathermal Climate | encyclopedia = Glossary of Meteorology | publisher = [[American Meteorological Society]] | url = http://amsglossary.allenpress.com/glossary/search?id=megathermal-climate1 | accessdate = 2008-05-21 }}</ref>
== Record ==
=== Modern ===
[[Image:Instrumental Temperature Record.png|thumb|right|200px|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 [[thermometer]]s, [[barometer]]s, and [[anemometer]]s 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.<ref>Spencer Weart. [http://www.aip.org/history/climate/20ctrend.htm The Modern Temperature Trend.] Retrieved on [[2007-06-01]].</ref>
=== 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.<ref>[[National Oceanic and Atmospheric Administration]]. [http://www.ncdc.noaa.gov/paleo/paleo.html NOAA Paleoclimatology.] Retrieved on [[2007-06-01]].</ref>
== Climate change ==
[[Image:Vostok-ice-core-petit.png|thumb|right|200px|Variations in CO<sub>2</sub>, temperature and dust from the [[Vostok, Antarctica|Vostok]] ice core over the past 450,000 years]]
{{seealso|Climate change|Global warming|temperature record|attribution of recent climate change}}
Climate change refers to the variation in the [[Earth]]'s global [[climate]] or in regional climates over time. It describes 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.<ref>Arctic Climatology and Meteorology. [http://nsidc.org/arcticmet/glossary/climate_change.html Climate change.] Retrieved on [[2008-05-19]].</ref>
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]] [[UNFCCC|Framework Convention on Climate Change]] (UNFCCC). The UNFCCC uses "climate variability" for non-human caused variations.<ref>
{{cite web |url=http://www.grida.no/climate/ipcc_tar/wg1/518.htm |title=Glossary |work=Climate Change 2001: The Scientific Basis. Contribution of Working Group I to the Third Assessment Report of the Intergovernmental Panel on Climate Change |accessdate=2008-05-22 |date=[[2001-01-20]] |publisher=[[Intergovernmental Panel on Climate Change]]}}
</ref>
Earth has undergone periodic climate shifts in the past, including four major [[ice age]]s. 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 gas]]es, 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 [[continent]]s, variations in the Earth's orbit, changes in the solar output, and vulcanism.<ref>Illinois State Museum (2002). [http://www.museum.state.il.us/exhibits/ice_ages/ Ice Ages.] Retrieved on [[2007-05-15]].</ref>
=== Climate models ===
{{seealso|Climate models|Climatology}}
Climate models use quantitative methods to simulate the interactions of the [[Earth's atmosphere|atmosphere]],<ref>Eric Maisonnave. [http://www.cerfacs.fr/globc/research/variability/ Climate Variability.] Retrieved on [[2008-05-02]].</ref> [[ocean]]s, 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 relating temperature to the build-up of greenhouse gases in the atmosphere, primarily [[carbon dioxide]] (see [[greenhouse gas]]). These models predict an upward trend in the [[surface temperature record|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 model]]s discretise and solve the full equations for mass and energy transfer and radiant exchange.<ref>Climateprediction.net. [http://www.climateprediction.net/science/model-intro.php Modelling the climate.] Retrieved on [[2008-05-02]].</ref>
== See also ==
{{WeatherPortal}}
* [[Climate change]]
* [[Biome]] - an [[ecology|ecological]] term for a major regional group of distinctive plant and animal communities best adapted to the region's physical environment
* [[Climatology]]
* [[Effect of sun angle on climate]]
* [[Electronic Climate Control]]
* [[Microclimate]]
* [[Solar variation]]
* [[Temperature extreme]]
* [[National Climatic Data Center]]
* [[Climate Prediction Center]]
== References ==
{{reflist|2}}
== External links ==
* [[IFAS]] [http://www.agclimate.org AgClimate]
* [http://128.194.106.6/~baum/climate_modeling.html Climate Models and modeling groups]
* [http://climateapps2.oucs.ox.ac.uk/cpdnboinc/ Climate Prediction Project]
* [http://www.worldclimate.com WorldClimate]
* [http://www.atmosphere.mpg.de/enid/1442 ESPERE Climate Encyclopaedia]
* [http://www.climate-zone.com Global Climate Data]
* [http://www.arctic.noaa.gov/climate.html Climate index and mode information]
* [http://www.beringclimate.noaa.gov/ A current view of the Bering Sea Ecosystem and Climate]
* [http://www.climate-charts.com/index.html Climate: Data and charts for world and US locations]
* [http://www.meteorologyclimate.com World climates list and articles]
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[[sr:Клима]]
[[sh:Klima]]
[[fi:Ilmasto]]
[[sv:Klimat]]
[[tg:Иқлим]]
[[tr:İklim]]
[[uk:Клімат]]
[[zh:氣候]]
[[sk:Podnebie]]