Climate is the statistics of weather over long periods of time.[1][2] It is measured by assessing the patterns of variation in temperature, humidity, atmospheric pressure, wind, precipitation, atmospheric particle count and other meteorological variables in a given region over long periods of time. Climate differs from weather, in that weather only describes the short-term conditions of these variables in a given region.

A region's climate is generated by the climate system, which has five components: atmosphere, hydrosphere, cryosphere, lithosphere, and biosphere.[3]

The climate of a location is affected by its latitude, terrain, and altitude, as well as nearby water bodies and their currents. Climates can be classified according to the average and the typical ranges of different variables, most commonly temperature and precipitation. The most commonly used classification scheme was the Köppen climate classification. The Thornthwaite system,[4] in use since 1948, incorporates evapotranspiration along with temperature and precipitation information and is used in studying biological diversity and how climate change affects it. The Bergeron and Spatial Synoptic Classification systems focus on the origin of air masses that define the climate of a region.

Paleoclimatology is the study 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. Climate change may occur over long and short timescales from a variety of factors; recent warming is discussed in global warming. Global warming results in redistributions. For example, "a 3°C change in mean annual temperature corresponds to a shift in isotherms of approximately 300–400 km in latitude (in the temperate zone) or 500 m in elevation. Therefore, species are expected to move upwards in elevation or towards the poles in latitude in response to shifting climate zones".[5][6]


Climate (from Ancient Greek klima, meaning inclination) is commonly defined as the weather averaged over a long period.[7] The standard averaging period is 30 years,[8] 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) 2001 glossary definition is as follows:

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 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.[9]

The World Meteorological Organization (WMO) describes climate "normals" as "reference points used by climatologists to compare current climatological trends to that of the past or what is considered 'normal'. A Normal is defined as the arithmetic average of a climate element (e.g. temperature) over a 30-year period. A 30 year period is used, as it is long enough to filter out any interannual variation or anomalies, but also short enough to be able to show longer climatic trends."[10] The WMO originated from the International Meteorological Organization which set up a technical commission for climatology in 1929. At its 1934 Wiesbaden meeting the technical commission designated the thirty-year period from 1901 to 1930 as the reference time frame for climatological standard normals. In 1982 the WMO agreed to update climate normals, and these were subsequently completed on the basis of climate data from 1 January 1961 to 31 December 1990.[11]

The difference between climate and weather is usefully summarized by the popular phrase "Climate is what you expect, weather is what you get."[12] 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: the thermohaline circulation of the ocean leads to a 5 °C (9 °F) warming of the northern Atlantic Ocean compared to other ocean basins.[13] 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,[14] 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.[15]

Other Languages
Afrikaans: Klimaat
Alemannisch: Klima
Ænglisc: Medumweder
العربية: مناخ
aragonés: Clima
armãneashti: Climâ
অসমীয়া: জলবায়ু
asturianu: Clima
Avañe'ẽ: Ararova
azərbaycanca: İqlim
বাংলা: জলবায়ু
Bân-lâm-gú: Khì-hāu
башҡортса: Климат
беларуская: Клімат
беларуская (тарашкевіца)‎: Клімат
भोजपुरी: जलवायु
български: Климат
Boarisch: Klima
bosanski: Klima
brezhoneg: Hin
català: Clima
Cebuano: Klima
čeština: Podnebí
Cymraeg: Hinsawdd
dansk: Klima
Deutsch: Klima
eesti: Kliima
Ελληνικά: Κλίμα
español: Clima
Esperanto: Klimato
euskara: Klima
فارسی: اقلیم
français: Climat
Frysk: Klimaat
Gaeilge: Aeráid
Gàidhlig: Gnàth-shìde
galego: Clima
한국어: 기후
Հայերեն: Կլիմա
हिन्दी: जलवायु
hrvatski: Klima
Ido: Klimato
Ilokano: Klima
Bahasa Indonesia: Iklim
interlingua: Climate
íslenska: Loftslag
italiano: Clima
עברית: אקלים
Basa Jawa: Iklim
ಕನ್ನಡ: ವಾಯುಗುಣ
къарачай-малкъар: Климат
ქართული: კლიმატი
қазақша: Климат
Kiswahili: Tabianchi
Kreyòl ayisyen: Klima
kurdî: Avhewa
Кыргызча: Климат
Latina: Clima
latviešu: Klimats
Lëtzebuergesch: Klima
lietuvių: Klimatas
Limburgs: Klimaat
magyar: Éghajlat
македонски: Клима
Malagasy: Toe-tany
მარგალური: კლიმატი
Bahasa Melayu: Iklim
Mirandés: Clima
монгол: Уур амьсгал
မြန်မာဘာသာ: ရာသီဥတု
Nederlands: Klimaat
नेपाल भाषा: लःफय्
日本語: 気候
нохчийн: Климат
Nordfriisk: Kliima
norsk: Klima
norsk nynorsk: Klima
occitan: Clima
oʻzbekcha/ўзбекча: Iqlim
ਪੰਜਾਬੀ: ਪੌਣਪਾਣੀ
پنجابی: کلائمیٹ
Papiamentu: Klima
Patois: Klaimit
Plattdüütsch: Klima
polski: Klimat
português: Clima
Qaraqalpaqsha: Klimat
română: Climat
русиньскый: Клімат
русский: Климат
sardu: Clima
Scots: Climate
Seeltersk: Klima
shqip: Klima
sicilianu: Clima
සිංහල: දේශගුණය
Simple English: Climate
سنڌي: آبھوا
slovenčina: Podnebie (klíma)
slovenščina: Podnebje
Soomaaliga: Cimilo
کوردی: ئاووھەوا
српски / srpski: Клима
srpskohrvatski / српскохрватски: Klima
Basa Sunda: Iklim
suomi: Ilmasto
svenska: Klimat
Tagalog: Klima
татарча/tatarça: Климат
тоҷикӣ: Иқлим
Türkçe: İklim
українська: Клімат
اردو: آب و ہوا
Vahcuengh: Heiqhaeuh
vèneto: Clima
Tiếng Việt: Khí hậu
Võro: Kliima
Winaray: Klema
吴语: 氣候
Xitsonga: Tinguva
ייִדיש: קלימאט
粵語: 氣候
Zazaki: İklım
中文: 氣候