Climatology is the study of climate, scientifically defined as weather conditions averaged over a period of time,^[1] and is a branch of the atmospheric sciences. Atmospheric sciences is an umbrella term for the study of the atmosphere, its processes the effects other systems have on the atmosphere and the effects of the atmosphere Meteorology (from Greek grc μετέωρος metéōros, "high in the sky" and grc -λογία -logia) is the Interdisciplinary The weather is a set of all the phenomena occurring in a given Atmosphere at a given Time. A tropical cyclone is a storm system characterized by a low pressure center and numerous Thunderstorms that produce strong winds and Flooding Climate encompasses the temperatures humidity rainfall atmospheric particle count and numerous other meteorogical factors in a given region over long periods of Climate change is any long-term significant change in the “average weather” that a given region experiences Climate encompasses the temperatures humidity rainfall atmospheric particle count and numerous other meteorogical factors in a given region over long periods of For other uses see Time (disambiguation Time is a component of a measuring system used to sequence events to compare the durations of Atmospheric sciences is an umbrella term for the study of the atmosphere, its processes the effects other systems have on the atmosphere and the effects of the atmosphere Basic knowledge of climate can be used within shorter term weather forecasting using analog techniques such as teleconnections and climate indices. Weather forecasting is the application of science and technology to predict the state of the atmosphere for a future time and a given location

Differences with meteorology

In contrast to meteorology, which studies short term weather systems lasting up to a few weeks, climatology studies the frequency and trends of those systems. Meteorology (from Greek grc μετέωρος metéōros, "high in the sky" and grc -λογία -logia) is the Interdisciplinary The weather is a set of all the phenomena occurring in a given Atmosphere at a given Time. It studies the periodicity of weather events over years to millennia, as well as changes in long-term average weather patterns, in relation to atmospheric conditions. Climatologists, those who practice climatology, study both the nature of climates - local, regional or global - and the natural or human-induced factors that cause climates to change. Climatology considers the past and can help predict future climate change. A prediction is a statement or claim that a particular Event will occur in the Future in more certain terms than a forecast. Climate change is any long-term significant change in the “average weather” that a given region experiences

Phenomena of climatological interest include the atmospheric boundary layer, circulation patterns, heat transfer (radiative, convective and latent), interactions between the atmosphere and the oceans and land surface (particularly vegetation, land use and topography), and the chemical and physical composition of the atmosphere. The planetary boundary layer ( PBL) also known as the atmospheric boundary layer ( ABL) or peplosphere, is the lowest part of the Atmosphere Atmospheric circulation is the large-scale movement of air and the means (together with the smaller Ocean circulation) by which Heat is distributed on the surface In thermal physics, heat transfer is the passage of Thermal energy from a hot to a colder body Thermal radiation is Electromagnetic radiation emitted from the surface of an object which is due to the object's Temperature. Convection in the most general terms refers to the movement of molecules within Fluids (i Latent heat flux is the flux of heat from the Earth's surface to the atmosphere that is associated with Evaporation of water at the surface and subsequent Condensation An ocean (from Greek, ''Okeanos'' (Oceanus) is a major body of saline water, and a principal component of the Hydrosphere. Vegetation is a general term for the plant life of a region it refers to the Ground cover provided by plants Land use' is also often used to refer to the distinct land use types in Zoning. Topography ( topo-, "place" and graphia, "writing" is the study of Earth 's Surface features or those of Planets Related disciplines include astrophysics, atmospheric physics, chemistry, ecology, geology, geophysics, glaciology, hydrology, oceanography, and volcanology. Astrophysics is the branch of Astronomy that deals with the Physics of the Universe, including the physical properties ( Luminosity, Atmospheric physics is the application of Physics to the study of the atmosphere. Chemistry (from Egyptian kēme (chem meaning "earth") is the Science concerned with the composition structure and properties Ecology (from Greek grc οἶκος oikos, "house(hold" and grc -λογία -logia) is the scientific study of Geology (from Greek γη gê, "earth" and λόγος Logos, "speech" lit Geophysics, a major discipline of Earth sciences, is the study of the Earth by quantitative physical methods especially by seismic, electromagnetic Glaciology (from Middle French dialect (Franco-Provençal glace, "ice" or Latin glacies, "frost ice" and Greek λόγος Hydrology (from Greek Yδωρ hudōr, "water" and λόγος logos, "study" is the study of the movement distribution and quality of Oceanography (from the greek words Ωκεανός meaning Ocean and γράφω meaning to write also called oceanology or Volcanology (also spelled vulcanology) is the study of Volcanoes, Lava, Magma, and related geological and Geophysical phenomena

History

Perhaps the earliest person to hypothesize the concept of climate change was the medieval Chinese scientist Shen Kuo (1031-1095 AD). Shen Kuo or Shen Kua ( (1031&ndash1095 style name Cunzhong and pseudonym Mengqi Weng, was a Polymathic Chinese Shen Kuo theorized that climates naturally shifted over an enormous span of time, after observing petrified bamboos found underground near Yanzhou (modern day Yan'an, Shaanxi province), a dry climate area unsuitable for the growth of bamboos. In Geology, petrifaction or petrification is the process by which Organic material is converted into stone or a similar substance without Bamboo is a group of Woody perennial Evergreen Plants in the True grass family Poaceae, subfamily Yan'an ( is a city in the Shanbei region of Shaanxi province in China. ( Postal map spelling: Shensi) is a north-central province of the People's Republic of China, and includes portions of the Loess

Early climate researchers include Edmund Halley, who published a map of the trade winds in 1686, after a voyage to the southern hemisphere. Edmond Halley FRS (ˈɛdmənd ˈhɔːlɪ ( November 8, 1656 &ndash January 14, 1742) was an English Astronomer Southern Hemisphere is the half of a Planet that is South of the Equator —the word hemisphere literally means 'half ball' Benjamin Franklin in the 18th century was the first to map the course of the Gulf Stream for use in sending mail overseas from the United States to Europe. Benjamin Franklin ( April 17 1790 was one of the Founding Fathers of the United States of America. The Gulf Stream, together with its northern extension towards Europe the North Atlantic Drift, is a powerful warm and swift Atlantic Ocean current that The United States of America —commonly referred to as the Francis Galton invented the term anticyclone. Sir Francis Galton FRS ( 16 February 1822 &ndash 17 January 1911) half-cousin of Charles Darwin, was an In Meteorology, an anticyclone (that is opposite to a Cyclone) is a Weather phenomenon in which there is a descending movement of the air and ^[2] Helmut Landsberg led to statistical analysis being used in climatology, which led to its evolution into a physical science. Helmut Erich Landsberg was a noted and influential Climatologist.

Different approaches

Map of the average temperature over 30 years. Data sets formed from the long-term average of historical weather parameters are sometimes called a "climatology".

Climatology is approached in a variety of ways. Paleoclimatology seeks to reconstruct past climates by examining records such as ice cores and tree rings (dendroclimatology). Paleoclimatology (also Palaeoclimatology) is the study of Climate change taken on the scale of the entire History of Earth. An ice core is a Core sample from the accumulation of snow and ice over many years that have re-crystallized and have trapped air bubbles from previous time periods Dendrochronology (from Greek grc δένδρον dendron, "tree" grc χρόνος khronos, "time" and grc -λογία Dendroclimatology is the science of determining past Climates from Trees (primarily Tree rings) Paleotempestology uses these same records to help determine hurricane frequency over millennia. Paleotempestology is the study of past Tropical cyclone activity by means of geological proxies as well as historical documentary records The study of contemporary climates incorporates meteorological data accumulated over many years, such as records of rainfall, temperature and atmospheric composition. Rain is Liquid precipitation. On Earth it is the condensation of atmospheric Water vapor into drops heavy enough to fall often making it to Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature Knowledge of the atmosphere and its dynamics is also embodied in models, either statistical or mathematical, which help by integrating different observations and testing how they fit together. Scientific modelling is the process of generating abstract, conceptual, Graphical and or mathematical models. Statistical models are used in Applied statistics. Three notions are sufficient to describe all statistical models Note The term model has a different meaning in Model theory, a branch of Mathematical logic. Modeling is used for understanding past, present and potential future climates. Historical climatology is the study of climate as related to human history and thus focuses only on the last few thousand years. Historical climatology is the study of historical changes in Climate and their effect on human history and development

Climate research is made difficult by the large scale, long time periods, and complex processes which govern climate. Climate is governed by physical laws that can be expressed as differential equations. A differential equation is a mathematical Equation for an unknown function of one or several variables that relates the values of the These equations are coupled and nonlinear, so that approximate solutions are obtained by using numerical methods to create global climate models. This article is about computer-driven prediction of Earth's climate for the theories and mathematics of climate modeling please see Climate model. Climate is sometimes modeled as a stochastic process but this is generally accepted as an approximation to processes that are otherwise too complicated to analyze. A stochastic process, or sometimes random process, is the counterpart to a deterministic process (or Deterministic system) in Probability theory.

Use in weather forecasting

Main article: Weather forecasting

A more complicated way of making a forecast, the analog technique requires remembering a previous weather event which is expected to be mimicked by an upcoming event. Weather forecasting is the application of science and technology to predict the state of the atmosphere for a future time and a given location What makes it a difficult technique to use is that there is rarely a perfect analog for an event in the future. ^[3] Some call this type of forecasting pattern recognition, which remains a useful method of observing rainfall over data voids such as oceans with knowledge of how satellite imagery relates to precipitation rates over land,^[4] as well as the forecasting of precipitation amounts and distribution in the future. A variation on this theme is used in Medium Range forecasting, which is known as teleconnections, when you use systems in other locations to help pin down the location of another system within the surrounding regime. Teleconnection in Atmospheric science refers to climate anomalies being related to each other at large distances (typically thousands of kilometers ^[5] One method of using teleconnections are by using climate indices such as ENSO-related phenomena. ^[6]

Climate indices

See also: El Niño, La Niña, Interdecadal Pacific Oscillation, Madden-Julian Oscillation, North Atlantic Oscillation, and Pacific Decadal Oscillation

Scientists use climate indices in their attempt to characterize and understand the various climate mechanisms that culminate in our daily weather. El Niño-Southern Oscillation ( ENSO; commonly referred to as simply El Niño) is a global coupled ocean-atmosphere phenomenon El Niño-Southern Oscillation ( ENSO; commonly referred to as simply El Niño) is a global coupled ocean-atmosphere phenomenon The Pacific Decadal Oscillation (PDO is a pattern of Pacific Climate variability that shifts phases on at least inter-decadal time scale usually about 20 to 30 years The North Atlantic oscillation (NAO is a climatic phenomenon in the North Atlantic Ocean of fluctuations in the difference of Sea-level pressure between The Pacific Decadal Oscillation (PDO is a pattern of Pacific Climate variability that shifts phases on at least inter-decadal time scale usually about 20 to 30 years Much in the way the Dow Jones Industrial Average, which is based on the stock prices of 30 companies, is used to represent the fluctuations in the stock market as a whole, climate indices are used to represent the essential elements of climate. The Dow Jones Industrial Average ( also called the DJIA, Dow 30, INDP, or informally the Dow Jones or The Dow) is one of several Climate indices are generally devised with the twin objectives of simplicity and completeness, and each index typically represents the status and timing of the climate factor it represents. By their very nature, indices are simple, and combine many details into a generalized, overall description of the atmosphere or ocean which can be used to characterize the factors which impact the global climate system.

El Niño - Southern Oscillation

El Niño impacts

La Niña impacts

El Niño-Southern Oscillation (ENSO) is a global coupled ocean-atmosphere phenomenon. The Pacific ocean signatures, El Niño and La Niña are important temperature fluctuations in surface waters of the tropical Eastern Pacific Ocean. The Pacific Ocean is the largest of the Earth 's Oceanic divisions The name El Niño, from the Spanish for "the little boy", refers to the Christ child, because the phenomenon is usually noticed around Christmas time in the Pacific Ocean off the west coast of South America. The Child Jesus, or Divine Infant, represents the infant Jesus until to the age of twelve South America is a Continent of the Americas, situated entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a ^[7] La Niña means "the little girl". ^[8] Their effect on climate in the subtropics and the tropics are profound. The atmospheric signature, the Southern Oscillation (SO) reflects the monthly or seasonal fluctuations in the air pressure difference between Tahiti and Darwin. Tahiti is the largest Island in the Windward group of French Polynesia, located in the Archipelago of Society Islands in the The most recent occurrence of El Niño started in September 2006^[9] and lasted until early 2007. September 2006 was marked by a controversy surrounding statements made by Pope Benedict XVI regarding Islam, during the same week as the fifth anniversary ^[10]

ENSO is a set of interacting parts of a single global system of coupled ocean-atmosphere climate fluctuations that come about as a consequence of oceanic and atmospheric circulation. Atmospheric circulation is the large-scale movement of air and the means (together with the smaller Ocean circulation) by which Heat is distributed on the surface ENSO is the most prominent known source of inter-annual variability in weather and climate around the world (~3 to 8 years), though not all areas are affected. ENSO has signatures in the Pacific, Atlantic and Indian Oceans. El Niño causes weather patterns which causes it to rain in specific places but not in others, this is one of many causes for the drought.

In the Pacific, during major warm events, El Niño warming extends over much of the tropical Pacific and becomes clearly linked to the SO intensity. While ENSO events are basically in phase between the Pacific and Indian Oceans, ENSO events in the Atlantic Ocean lag behind those in the Pacific by 12 to 18 months. Many of the countries most affected by ENSO events are developing countries within main continents (South America, Africa. . . ), with economies that are largely dependent upon their agricultural and fishery sectors as a major source of food supply, employment, and foreign exchange. New capabilities to predict the onset of ENSO events in the three oceans can have global socio-economic impacts. While ENSO is a global and natural part of the Earth's climate, whether its intensity or frequency may change as a result of global warming is an important concern. Low-frequency variability has been evidenced: the quasi-decadal oscillation (QDO). Inter-decadal (ID) modulation of ENSO (from PDO or IPO) might exist. This could explain the so-called protracted ENSO of the early 90s.

Madden-Julian Oscillation

Note how the MJO moves eastward with time.

The Madden-Julian Oscillation (MJO) is an equatorial traveling pattern of anomalous rainfall that is planetary in scale. It is characterized by an eastward progression of large regions of both enhanced and suppressed tropical rainfall, observed mainly over the Indian Ocean and Pacific Ocean. The Indian Ocean is the third largest of the world's Oceanic divisions covering about 20% of the water on the Earth 's surface The Pacific Ocean is the largest of the Earth 's Oceanic divisions The anomalous rainfall is usually first evident over the western Indian Ocean, and remains evident as it propagates over the very warm ocean waters of the western and central tropical Pacific. This pattern of tropical rainfall then generally becomes very nondescript as it moves over the cooler ocean waters of the eastern Pacific but reappears over the tropical Atlantic and Indian Ocean. The wet phase of enhanced convection and precipitation is followed by a dry phase where convection is suppressed. Each cycle lasts approximately 30-60 days. The MJO is also known as the 30-60 day oscillation, 30-60 day wave, or intraseasonal oscillation.

North Atlantic Oscillation (NAO)

Indices of the NAO are based on the difference of normalized sea level pressure (SLP) between Ponta Delgada, Azores and Stykkisholmur/Reykjavik, Iceland. The SLP anomalies at each station were normalized by division of each seasonal mean pressure by the long-term mean (1865-1984) standard deviation. Normalization is done to avoid the series of being dominated by the greater variability of the northern of the two stations. Positive values of the index indicate stronger-than-average westerlies over the middle latitudes. ^[11]

Northern Annualar Mode (NAM) or Arctic Oscillation (AO)

The NAM, or AO, is defined as the first EOF of northern hemisphere winter SLP data from the tropics and subtropics. It explains 23% of the average winter (December-March) variance, and it is dominated by the NAO structure in the Atlantic. Although there are some subtle differences from the regional pattern over the Atlantic and Arctic, the main difference is larger amplitude anomalies over the North Pacific of the same sign as those over the Atlantic. This feature gives the NAM a more annular (or zonally-symmetric) structure. ^[11]

Northern Pacific (NP) Index

The NP Index is the area-weighted sea level pressure over the region 30N-65N, 160E-140W. ^[11]

Pacific Decadal Oscillation (PDO)

The PDO is a pattern of Pacific climate variability that shifts phases on at least inter-decadal time scale, usually about 20 to 30 years. The Pacific Ocean is the largest of the Earth 's Oceanic divisions Climate change is any long-term significant change in the “average weather” that a given region experiences The PDO is detected as warm or cool surface waters in the Pacific Ocean, north of 20° N. The Pacific Ocean is the largest of the Earth 's Oceanic divisions During a "warm", or "positive", phase, the west Pacific becomes cool and part of the eastern ocean warms; during a "cool" or "negative" phase, the opposite pattern occurs. The mechanism by which the pattern lasts over several years has not been identified; one suggestion is that a thin layer of warm water during summer may shield deeper cold waters. A PDO signal has been reconstructed to 1661 through tree-ring chronologies in the Baja California area. Baja California (pronounced ˈbɑːhɑː kælɨˈfɔrnjə in English is the northernmost state of Mexico.

Interdecadal Pacific Oscillation (IPO)

The Interdecadal Pacific Oscillation (IPO or ID) display similar sea surface temperature (SST) and sea level pressure patterns to the PDO, with a cycle of 15–30 years, but affects both the north and south Pacific. In the tropical Pacific, maximum SST anomalies are found away from the equator. This is quite different from the quasi-decadal oscillation (QDO) with a period of 8-to-12 years and maximum SST anomalies straddling the equator, thus resembling ENSO.

Climate models

Main article: Climate models

Climate models use quantitative methods to simulate the interactions of the atmosphere, oceans, land surface, and ice. This article is about the theories and mathematics of climate modeling Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five An ocean (from Greek, ''Okeanos'' (Oceanus) is a major body of saline water, and a principal component of the Hydrosphere. 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 unbalance 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 emissions of carbon dioxide (see greenhouse gas). Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single Greenhouse gases are gaseous constituents of the atmosphere bothnatural and anthropogenic that absorb and emit radiation at specific wavelengths within the spectrum of thermal infrared These models predict an upward trend in the surface temperature record, as well as a more rapid increase in temperature at higher altitudes. See also Temperature record. The instrumental temperature record shows the fluctuations of the Temperature of the atmosphere and the oceans as

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. Sea ice is formed from Ocean water that freezes Because the Oceans consist of Saltwater, this occurs at about -1 This article is about computer-driven prediction of Earth's climate for the theories and mathematics of climate modeling please see Climate model.

See also

• Climate
• Edmund Halley
• Helmut Landsberg
• Meteorology
• Paleoclimatology
• Paleotempestology
• Tornado climatology
• Tropical cyclone rainfall climatology
• National Climatic Data Center
• Climate Prediction Center

References

External links

• Climatology News Daily publication with news in all areas of climatology plus free news feeds for webmasters.
• Climate Prediction Center
• IPCC Intergovernmental Panel on Climate Change: The IPCC assesses the scientific, technical and socio-economic information relevant for the understanding of the risk of human-induced climate change.
• KNMI Climate Explorer The Royal Netherlands Meteorological Institute's Climate Explorer graphs climatological relationships of spatial and temporal data.
• Climatology as a Profession Amer. Inst. of Physics account of the history of the discipline of climatology in the 20th century