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The science that deals with the phenomena of the atmosphere, especially weather and weather conditions.
[French météorologie, from Greek meteōrologiā, discussion of astronomical phenomena : meteōron, astronomical phenomenon; see meteor + -logiā, -logy.]
meteorological me'te·or·o·log'i·cal (-ər-ə-lŏj'ĭ-kəl) or me'te·or·o·log'ic adj.A discipline involving the study of the atmosphere and its phenomena. Meteorology and climatology are rooted in different parent disciplines, the former in physics and the latter in physical geography. They have, in effect, become interwoven to form a single discipline known as the atmospheric sciences, which is devoted to the understanding and prediction of the evolution of planetary atmospheres and the broad range of phenomena that occur within them. The atmospheric sciences comprise a number of interrelated subdisciplines. See also Climatology.
Atmospheric dynamics (or dynamic meteorology) is concerned with the analysis and interpretation of the three-dimensional, time-varying, macroscale motion field. It is a branch of fluid dynamics, specialized to deal with atmospheric motion systems on scales ranging from the dimensions of clouds up to the scale of the planet itself. The activity within dynamic meteorology that is focused on the description and interpretation of large-scale (greater than 1000 km or 600 mi) tropospheric motion systems such as extratropical cyclones has traditionally been referred to as synoptic meteorology, and that devoted to mesoscale (10–1000 km or 6–600 mi) weather systems such as severe thunderstorm complexes is referred to as mesometeorology. Both synoptic meteorology and mesometeorology are concerned with phenomena of interest in weather forecasting, the former on the day-to-day time scale and the latter on the time scale of minutes to hours. See also Dynamic meteorology; Mesometeorology.
The complementary field of atmospheric physics (or physical meteorology) is concerned with a wide range of processes that are capable of altering the physical properties and the chemical composition of air parcels as they move through the atmosphere. It may be viewed as a branch of physics or chemistry, specializing in processes that are of particular importance within planetary atmospheres. Overlapping subfields within atmospheric physics include cloud physics, which is concerned with the origins, morphology, growth, electrification, and the optical and chemical properties of the droplets within clouds; radiative transfer, which is concerned with the absorption, emission, and scattering of solar and terrestrial radiation by aerosols and radiatively active trace gases within planetary atmospheres; atmospheric chemistry, which deals with a wide range of gas-phase and heterogeneous (that is, involving aerosols or cloud droplets) chemical and photochemical reactions on space scales ranging from individual smokestacks to the global ozone layer; and boundary-layer meteorology or micrometeorology, which is concerned with the vertical transfer of water vapor and other trace constituents, as well as heat and momentum across the interface between the atmosphere and the underlying surfaces and their redistribution within the lowest kilometer of the atmosphere by motions on scales too small to resolve explicitly in global models. Aeronomy is concerned with physical processes in the upper atmosphere (above the 50-km or 30-mi level). See also Aeronomy; Atmospheric chemistry; Atmospheric electricity; Atmospheric general circulation; Atmospheric waves, upper synoptic; Cloud physics; Meteorological optics; Micrometeorology; Radiative transfer.
Although atmospheric dynamics and atmospheric physics in some circumstances can be successfully pursued as separate disciplines, important problems such as the development of numerical weather prediction models and the understanding of the global climate system require a synthesis. Physical processes such as radiative transfer and the condensation of water vapor onto cloud droplets are ultimately responsible for the temperature gradients that drive atmospheric motions, and the motion field, in turn, determines the evolving, three-dimensional setting in which the physical processes take place.
The atmospheric sciences cannot be completely isolated from related disciplines. On time scales longer than a month, the evolution of the state of the atmosphere is influenced by dynamic and thermodynamic interactions with the other elements of the climate system, that is, the oceans, the cryosphere, and the terrestrial biosphere. A notable example is the El Niño-Southern Oscillation phenomenon in the equatorial Pacific Ocean, in which changes in the distribution of surface winds force anomalous ocean currents; the currents can alter the distribution of sea-surface temperature, which in turn can alter the distribution of tropical rainfall, thereby inducing further changes in the surface wind field. On a time scale of decades or longer, the cycling of chemical species such as carbon, nitrogen, and sulfur between these same global reservoirs also influences the evolution of the climate system. Human activities represent an increasingly significant atmospheric source of some of the radiatively active trace gases that play a role in regulating the temperature of the Earth. See also Biosphere; Maritime meteorology; Tropical meteorology.
Throughout the atmospheric sciences, prediction is a unifying theme that sets the direction for research and technological development. Prediction on the time scale of minutes to hours is concerned with severe weather events such as tornadoes, hail, and flash floods, which are manifestations of intense mesoscale weather systems, and with urban air-pollution episodes; day-to-day prediction is usually concerned with the more ordinary weather events and changes that attend the passage of synoptic-scale weather systems such as extratropical cyclones; and seasonal prediction is concerned with regional climate anomalies such as drought or recurrent and persistent cold air outbreaks. Prediction on still longer time scales involves issues such as the impact of human activity on the temperature of the Earth, regional climate, the ozone layer, and the chemical makeup of precipitation. See also Climate modeling; Drought; Hail; Tornado.
The evolution of the atmospheric sciences from a largely descriptive field to a mature, quantitative physical science discipline is apparent in the development of vastly improved predictive capabilities based upon the numerical integration of specialized versions of the Navier-Stokes equations, which include sophisticated parametrizations of physical processes such as radiative transfer, latent heat release, and microscale motions. The so-called numerical weather prediction models have largely replaced the subjective and statistical prediction methods that were widely used as a basis for day-to-day weather forecasting. The state-of-the-art numerical models exhibit significant skill for forecast intervals as long as about a week. See also
A distinction is often made between weather prediction, which is largely restricted to the consideration of dynamic and physical processes internal to the atmosphere, and climate prediction, in which interactions between the atmosphere and other elements of the climate system are taken into account. The importance and complexity of these interactions tend to increase with the time scale of the phenomena of interest in the forecast. Weather prediction involves shorter time frames (days to weeks), in which the information contained in the initial conditions is the dominant factor in determining the evolution of the state of the atmosphere; and climate prediction involves longer time frames (seasons and longer), for boundary forcing is the dominant factor in determining the state of the atmosphere.
Atmospheric prediction has benefited greatly from major advances in remote sensing. Geostationary and polar orbiting satellites provide continuous surveillance of the global distribution of cloudiness, as viewed with both visible and infrared imagery. These images are used in positioning of features such as cyclones and fronts on synoptic charts. Cloud motion vectors derived from consecutive images provide estimates of winds in regions that have no other data. Passive infrared and microwave sensors aboard satellites also provide information on the distribution of sea-surface temperature, sea state, land-surface vegetation, snow and ice cover, as well as vertical profiles of temperature and moisture in cloud-free regions. Improved ground-based radar imagery and vertical profiling devices provide detailed coverage of convective cells and other significant mesoscale features over land areas. Increasingly sophisticated data assimilation schemes are being developed to incorporate this variety of information into numerical weather prediction models on an operational basis. See also Atmosphere; Cyclone; Front; Radar meteorology; Satellite meteorology; Weather forecasting and prediction.
The study of the character of the atmosphere and the events and processes within it, together with the interaction between the atmosphere and the face of the earth.
For more information on meteorology, visit Britannica.com.
Meteorology, the study of the atmosphere and, especially, of weather.
Colonial and Early America
Early settlers in the New World found the Climate harsher and the storms more violent than in the Old World. Many colonial Americans kept weather journals but, compared to European standards, few had adequate instruments. The first prolonged instrumental meteorological observations, initiated by Dr. John Lining in Charleston in 1738, were related to his medical concerns.
In 1750 Benjamin Franklin hypothesized that grounded metal rods would protect buildings from lightning damage. Two years later he conducted his famous kite experiment. Franklin's investigations demonstrated that lightning is an electrical discharge and that most flashes originate in clouds. Franklin coined much of the vocabulary of modern electricity, including such terms as positive and negative charge. He was able to simulate many types of lightning damage and demonstrated that lightning rods would protect most structures from such effects. Franklin also suggested that the aurora borealis is of electrical origin and closely associated with terrestrial magnetism, that storms are progressive wind systems, and, on a practical note, that the government should set up an office to administer aid to citizens whose crops or property had been destroyed by hurricanes, tornadoes, blights, or pestilence. During several Atlantic crossings between 1746 and 1775, Franklin made observations of the warm current called the Gulf Stream and was able to chart its boundaries fairly accurately.
Thomas Jefferson and the Reverend James Madison made the first simultaneous meteorological measurements in America in 1778. Jefferson also exchanged observations regularly with his other numerous correspondents. He 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 these plans did not materialize in his lifetime, within several decades voluntary observing systems were replaced by government-run meteorological services around the world.
The Nineteenth Century
Early in the nineteenth century the Army Medical Department, the General Land Office, and the academies of the State of New York established large-scale climatological observing programs. The information was used in a variety of ways: physicians studied the relationship between weather and health, farmers and settlers used the temperature and rainfall statistics, and educators brought meteorological observations into the classroom.
Between 1834 and 1859 the "American storm controversy" stimulated a meteorological crusade that transformed theory and practice. William Redfield, James Pollard Espy, and Robert Hare argued over the nature and causes of storms and the proper way to investigate them. Redfield focused on hurricanes as circular whirlwinds; Espy on the release of latent "caloric" in updrafts; and Hare on the role of electricity in storms. Espy also prepared the first long series of daily-analyzed weather charts and was the first official government meteorologist of the United States. While it came to no clear intellectual resolution, the controversy of the 1830s and 1840s stimulated the development of observational projects at the American Philosophical Society, Franklin Institute, and Smithsonian Institution. In the 1840s Matthew Fontaine Maury, superintendent of the U.S. Navy's Depot of Charts and Instruments prepared "pilot charts" of ocean winds and currents. The charts, compiled from navy logbooks and reports from ship captains, included sailing directions for mariners on all the world's oceans.
The Smithsonian meteorological project under the direction of Joseph Henry provided a uniform set of procedures and some standardized instruments to observers across the continent. Up to 600 volunteer observers filed reports monthly. In 1849 Henry began compiling weather reports collected from telegraph operators and displayed the results on a large map of the nation. In addition the Smithsonian established cooperative observing programs with the Navy Department, the states of New York and Massachusetts, the Canadian Government, the Coast Survey, the Army Engineers, the Patent Office, and the Department of Agriculture. The Smithsonian sponsored original research on storms, climatic change, and phenology (the study of recurring natural phenomena, especially in relation to climatic conditions); it also published and distributed meteorological reports, maps, and translations. James Coffin mapped the winds of the Northern Hemisphere and the winds of the globe using data collected through Smithsonian exchanges. William Ferrel used this information to develop his theory of the general circulation of the atmosphere. Elias Loomis improved weather-plotting methods and developed synoptic charts depicting winds, precipitation, isotherms, and lines of minimum pressure.
In 1870 Congress provided funds for a national weather service. Assigned to the Signal Service Corps within the War Department, the new service was called the Division of Telegrams and Reports for the Benefit of Commerce. General Albert J. Myer served as the first director of the service, which provided daily reports of current conditions and "probabilities" for the next day's weather. It employed civilian scientists Increase A. Lapham and Cleveland Abbe and more than 500 college-educated observer-sergeants. Its budget increased one hundredfold from 1869 to 1875. The Monthly Weather Review, begun in 1872, was still published in the early 2000s. Beginning in 1875, in cooperation with the weather services of other nations, the weather service issued a Bulletin of International Simultaneous Observations, which contained worldwide synoptic charts and weather observations. In 1891 the U.S. Weather Bureau moved to the Department of Agriculture.
The Twentieth Century
During World War I the bureau instituted the daily launching of upper-air sounding balloons, applied twoway radio communication to meteorological purposes, and developed marine and aviation weather services. The "disciplinary" period in meteorology began rather late compared with parallel developments in other sciences. University and graduate education, well-defined career paths, and specialized societies and journals began in the second decade of the twentieth century. The American Meteorological Society and the American Geophysical Union were both established in 1919.
In the 1930s a number of visiting scientists from Scandinavia, including Vilhelm Bjerknes, Jacob Bjerknes, C. G. Rossby, and Sverre Petterssen brought the new Bergen School methods of air-mass and frontal analysis to the United States. In 1940, to serve the growing needs of aviation, the Weather Bureau was transferred to the Department of Commerce. By this time the use of Bergen School methods and the acquisition of upper-air data by the use of balloon-borne radio-meteorographs had become routine.
During World War II meteorologists instituted crash education programs to train weather officers. Forecasters were needed for bombing raids, naval task forces, and other special operations. Many university departments of meteorology were established at this time. Testing and use of nuclear explosives also raised new issues for meteorologists. Scientists learned that radioactive fallout spreads in an ominous plume downwind and circles the globe at high altitudes in the jet stream. Atmospheric scientists played leading roles in promoting the Limited Test Ban Treaty of 1963, which banned atmospheric nuclear testing. That year, the original Clean Air Act was passed. It was substantially revised in 1970 and in 1990.
Following the war, surplus radar equipment and airplanes were employed in storm studies. At the Research Laboratory of the General Electric Company, Irving Langmuir, a Nobel Prize–winning chemist, and his associates Vincent Schaefer and Bernard Vonnegut experimented with weather modification using dry ice, silver iodide, and other cloud-seeding agents. Although these techniques did not result in their originally intended goal—large-scale weather control—they did provide impetus to the new field of cloud physics. Meanwhile, at the Institute for Advanced Study in Princeton, John von Neumann began experiments using digital computers to model and predict the weather. With the support of the weather bureau and the military weather services, operational numerical weather prediction became a reality by the mid-1950s. Viewing the earth from space had also become a reality. In 1947 cloud formations were photographed from high altitude using a V2 rocket. Explorer 6 took the first photograph of the earth from space in 1959, while in the same year Explorer 7 measured the radiation budget of the earth with a pair of infrared radiometers with spin-scan stabilization designed and built by Verner Suomi. Tiros 1 (Tele-vision Infra-Red Observation Satellite), the world's first all-weather satellite, was launched into polar orbit by NASA in 1960.
Radio weather forecasts date to 1923, when E. B. Rideout began broadcasting in Boston. Televised weathercasts were first aired on the Weather Bureau Dumont Network in 1947 by James M. "Jimmie" Fidler. In 1982 the Weather Channel started round-the-clock cable operations. In 1965 the Weather Bureau became part of the Environmental Science Services Administration (ESSA); it was renamed the National Weather Service in 1970 as part of the new National Oceanic and Atmospheric Administration (NOAA).
Conclusion
New interdisciplinary problems, approaches, and techniques characterize the modern subdisciplines of the atmospheric sciences. Specialties in cloud physics, atmospheric chemistry, satellite meteorology, and climate dynamics have developed along with more traditional programs in weather analysis and prediction. The U.S. National Center for Atmospheric Research and many new departments of atmospheric science date from the 1960s. Fundamental contributions have been made by Edward Lorenz on the chaotic behavior of the atmosphere, by F. Sherwood Rowland and Mario Molina on potential damage to stratospheric ozone by chlorofluorocarbon (CFC) compounds, and by Charles David Keeling on background measurements of carbon dioxide, to name but a few.
Meteorology has advanced through theoretical understanding and through new technologies such as aviation, computers, and satellites, which have enhanced data collection and observation of the weather. Economic and social aspects of meteorology now include practical fore-casting, severe weather warnings, and governmental and diplomatic initiatives regarding the health and future of the planet.
Bibliography
Bates, Charles C., and John F. Fuller. America's Weather Warriors, 1814–1985. College Station: Texas A&M University Press, 1986.
Fleming, James Rodger. Meteorology in America, 1800–1870. Baltimore: Johns Hopkins University Press, 1990.
Fleming, James Rodger, ed. Historical Essays on Meteorology, 1919–1995. Boston: American Meteorological Society, 1996.
Nebeker, Frederik. Calculating the Weather: Meteorology in the Twentieth Century. San Diego, Calif.: Academic Press, 1995.
Whitnah, Donald R. A History of the United States Weather Bureau. Urbana: University of Illinois Press, 1961.
Development of Meteorology
Aristotle's Meteorologica (c.340 B.C.) is the oldest comprehensive treatise on meteorological subjects. Although most of the discussion is inaccurate in the light of modern understanding, Aristotle's work was respected as the authority in meteorology for some 2,000 years. In addition to further commentary on the Meteorologica, this period also saw attempts to forecast the weather according to astrological events, using techniques introduced by Ptolemy.
As speculation gave way to experimentation following the scientific revolution, advances in the physical sciences made contributions to meteorology, most notably through the invention of instruments for measuring atmospheric conditions, e.g., Leonardo da Vinci's wind vane (1500), Galileo's thermometer (c.1593), and Torricelli's mercury barometer (1643). Further developments included Halley's account of the trade winds and monsoons (1686) and Ferrel's theory of the general circulation of the atmosphere (1856). The invention of the telegraph made possible the rapid collection of nearly simultaneous weather observations for large continental and marine regions, thus providing a view of the large-scale pressure and circulation patterns that determine the weather.
Modern Meteorological Science and Technology
In 1917 the Norwegian physicist Vilhelm Bjerknes introduced his theory describing the formation of wave cyclones on the polar front and laid the foundation for modern methods of weather forecasting. In 1922, L. F. Richardson perceived the basis for the mathematical prediction of the atmospheric circulation, and in 1938 C. G. Rossby made additional mathematical contributions. Application of this treatment by Richardson and Rossby awaited the introduction of high-speed electronic computers, which were first used for weather forecasting in the late 1940s by J. G. Charney and John Von Neumann. By 1955 computer forecasts were being made operationally and computer forecasting models have been improved steadily since then.
Since 1959 meteorological satellites have provided an overview of the atmosphere's cloud patterns, serving among other things as an early warning and detection system for hurricanes, typhoons, and tropical cyclones. Infrared sensors mounted on meteorological satellites now provide observations of the vertical temperature structure of the atmosphere, and research efforts continue the development of computer forecasting models capable of utilizing these and other satellite data to improve current weather-predicting skills. Meteorological studies have been aided by the use of large computers for atmospheric modeling. Information gathered by weather balloons and earth-orbiting satellites have been used in computer models to predict long-term and short-term meteorological events such as changes in ozone levels and daily movements of storms, respectively.
The National Oceanic and Atmospheric Administration (NOAA) has the major governmental responsibility in the United States for monitoring and forecasting the weather and conducting meteorological research. The Air Weather Service and the Fleet Numerical Weather Control have similar responsibilities within the U.S. Air Force and U.S. Navy, respectively; space applications to meteorology are researched by the National Aeronautics and Space Administration (NASA) as well as by the National Environmental Satellite Service, which is under the auspices of NOAA. In addition to a host of universities conducting meteorological research, there is the National Center for Atmospheric Research, which is operated by an affiliation of universities and sponsored by the U.S. National Science Foundation. The World Weather Watch, organized by the World Meteorological Organization, collects and disseminates information on a global basis. A number of private companies also engage in operational and research meteorological activities.
Bibliography
See C. D. Ahrens, Meteorology Today (1988); J. M. Moran, Meteorology (1991).
(DOD) The study dealing with the phenomena of the atmosphere including the physics, chemistry, and dynamics extending to the effects of the atmosphere on the earth's surface and the oceans.
Meteorology is a very inexact science because of the possibility of fast changes in the atmosphere.
Tutor's tip: Peter's studies in "meteorology" (the science of weather) and "metrology" (the science of weights and measures) came in handy when he sailed the Pacific.
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Meteorology (from Greek: μετέωρον, meteoron, "high in the sky"; and λόγος, logos, "knowledge") is the interdisciplinary scientific study of the atmosphere that focuses on weather processes and forecasting. Meteorological phenomena are observable weather events which illuminate and are explained by the science of meteorology. Those events are bound by the variables that exist in Earth's atmosphere. They are temperature, pressure, water vapor, and the gradients and interactions of each variable, and how they change in time. The majority of Earth's observed weather is located in the troposphere. [1] [2]
Meteorology, climatology, atmospheric physics,
and atmospheric chemistry are sub-disciplines of the atmospheric sciences. Meteorology and hydrology compose the
interdisciplinary field of hydrometeorology.
Interactions between Earth's atmosphere and the oceans are part of coupled ocean-atmosphere studies. Meteorology has application in many diverse fields such as the military, energy production, farming, shipping and construction.
In the study of the atmosphere, meteorology can be academically subdivided depending on the temporal scope and spatial scope of interest. In one extreme, meteorology seems to be left behind and becomes climatology. In the timescales of hours to days, meteorology separates into micro-, meso-, and synoptic scale meteorology. Respectively, the geospatial size of each of these three scales relates directly with the appropriate timescale.
Other subclassifications are available due to the need by humans, or by the unique, local or broad effects that are studied within that sub-class.
Boundary layer meteorology is the study of processes in the air layer directly above Earth's surface, known as the atmospheric boundary layer (ABL) or peplosphere. The effects of the surface – heating, cooling, and friction – cause turbulent mixing within the air layer. Significant fluxes of heat, matter, or momentum on time scales of less than a day are advected by turbulent motions.[3] Boundary layer meteorology includes the study of all types of surface-atmosphere boundary, including ocean, lake, urban land and non-urban land.
Mesoscale meteorology is the study of atmospheric phenomena that has horizontal scales ranging from microscale limits to synoptic scale limits and a vertical scale that starts at the Earth's surface and includes the atmospheric boundary layer, troposphere, tropopause, and the lower section of the stratosphere. Mesoscale timescales last from less than a day to the lifetime of the event, which in some cases can be weeks. The events typically of interest are thunderstorms, squall lines, fronts, precipitation bands in tropical and extratropical cyclones, and topographically generated weather systems such as mountain waves and sea and land breezes.[4]
Synoptic scale is generally large area dynamics referred to in horizontal coordinates and with respect to time. The phenomena typically described by synoptic meteorology include events like extratropical cyclones, baroclinic troughs and ridges, frontal zones, and to some extent jets. All of these are typically given on weather maps for a specific time. The minimum horizontal scale of synoptic phenomena are limited to the spacing between surface observation stations. [5]
The study of weather patterns in this area includes the transport of heat from the tropics to the poles. Also, very large scale oscillations are of extreme importance. Those oscillations have time periods typically longer than a full annual seasonal cycle, such as ENSO, PDO, MJO, etc. Global scale pushes the thresholds of the perception of meteorology into climatology. The traditional definition of climate is pushed in to larger timescales with the further understanding of how the global oscillations cause both climate and weather disturbances in the synoptic and mesoscale timescales.
Numerical Weather Prediction is a main focus in understanding air-sea interaction, tropical meteorology, atmospheric predictability, and tropospheric/stratospheric processes.[6]. Currently (2007) Naval Research Laboratory in Monterey produces the atmospheric model called NOGAPS, a global scale atmospheric model, this model is run operationaly at Fleet Numerical Meteorology and Oceanography Center. There are several other globa atmospheric models.
Dynamic meteorology generally focuses on the physics of the atmosphere. The idea of air parcel is used to define the smallest element of the atmosphere, while ignoring the discrete molecular and chemical nature of the atmosphere. An air parcel is defined as a point in the fluid continuum of the atmosphere. The fundamental laws of fluid dynamics, thermodynamics, and motion are used to study the atmosphere. The physical quantities that characterize the state of the atmosphere are temperature, density, pressure, etc. These variables have unique values in the continuum.[7]
Aviation meteorology deals with the impact of weather on air traffic management. It is important for air crews to understand the implications of weather on their flight plan as well as their aircraft, as noted by the Aeronautical Information Manual[8]:
The effects of ice on aircraft are cumulative-thrust is reduced, drag increases, lift lessens, and weight increases. The results are an increase in stall speed and a deterioration of aircraft performance. In extreme cases, 2 to 3 inches of ice can form on the leading edge of the airfoil in less than 5 minutes. It takes but 1/2 inch of ice to reduce the lifting power of some aircraft by 50 percent and increases the frictional drag by an equal percentage.[9]
Meteorologists, soil scientists, agricultural hydrologists, and agronomists are persons concerned with studying the effects of weather and climate on plant distribution, crop yield, water-use efficiency, phenology of plant and animal development, and the energy balance of managed and natural ecosystems. Conversely, they are interested in the role of vegetation on climate and weather.[10]
Hydrometeorology is the branch of meteorology that deals with the hydrologic cycle, the water budget, and the rainfall statistics of storms.[11] A hydrometeorologist prepares and issues forecasts of accumulating (quantitative) precipitation, heavy rain, heavy snow, and highlights areas with the potential for flash flooding. Typically the range of knowledge that is required overlaps with climatology, mesoscale and synoptic meteorology, and other geosciences.[12]
The arrival of the electrical telegraph in 1837 afforded, for the first time, a practical method for quickly gathering information on surface weather conditions from over a wide area. This data could be used to produce maps of the state of the atmosphere for a region near the Earth's surface and to study how these states evolved through time. To make frequent weather forecasts based on these data required a reliable network of observations, but it was not until 1849 that the Smithsonian Institute began to establish an observation network across the United States under the leadership of Joseph Henry [13]. Similar observation networks were established in Europe at this time. In 1854, the United Kingdom government appointed Robert FitzRoy to the new office of Meteorological Statist to the Board of Trade with the role of gathering weather observations at sea. FitzRoy's office became the United Kingdom Meteorological Office in 1854, the first national meteorological service in the world. The first daily weather forecasts made by FitzRoy's Office were published in The Times newspaper in 1860. The following year a system was introduced of hoisting storm warning cones at principal ports when a gale was expected.
Over the next 50 years many countries established national meteorological services: Finnish Meteorological Central Office (1881) was formed from part of Magnetic Observatory of Helsinki University; India Meteorological Department (1889) established following tropical cyclone and monsoon related famines in the previous decades; United States Weather Bureau (1890) was established under the Department of Agriculture; Australian Bureau of Meteorology (1905) established by a Meteorology Act to unify existing state meteorological services.
Understanding the kinematics of how exactly the rotation of the Earth affects airflow was partial at first. Late in the 19th century the full extent of the large scale interaction of pressure gradient force and deflecting force that in the end causes air masses to move along isobars was understood. Early in the 20th century this deflecting force was named the Coriolis effect after Gaspard-Gustave Coriolis, who had published in 1835 on the energy yield of machines with rotating parts, such as waterwheels. In 1856, William Ferrel proposed the existence of a circulation cell in the mid-latitudes with air being deflected by the Coriolis force to create the prevailing westerly winds.
In 1904 the Norwegian scientist Vilhelm Bjerknes first postulated that prognostication of the weather is possible from calculations based upon natural laws.
Early in the 20th century, advances in the understanding of atmospheric physics led to the foundation of modern numerical weather prediction. In 1922, Lewis Fry Richardson published `Weather prediction by numerical process` which described how small terms in the fluid dynamics equations governing atmospheric flow could be neglected to allow numerical solutions to be found. However, the sheer number of calculations required was too large to be completed before the advent of computers.
At this time in Norway a group of meteorologists led by Vilhelm Bjerknes developed the model that explains the generation, intensification and ultimate decay (the life cycle) of mid-latitude cyclones, introducing the idea of fronts, that is, sharply defined boundaries between air masses. The group included Carl-Gustaf Rossby (who was the first to explain the large scale atmospheric flow in terms of fluid dynamics), Tor Bergeron (who first determined the mechanism by which rain forms) and Jacob Bjerknes.
Starting in the 1950s,
In the 1960s, the chaotic nature of the atmosphere was first observed and understood by Edward Lorenz, founding the field of chaos theory. These advances have led to the current use of ensemble forecasting in most major forecasting centers, to take into account uncertainty arising due to the chaotic nature of the atmosphere.
Generally speaking, each science has its own unique sets of laboratory equipment. However, Meteorology is a science short on "lab" equipment and long or wide on field-mode observation equipment, see List of weather instruments. In some aspects this may appear to be nice, but in reality can make simple observations slide on the erroneous side.
In science, an observation, or observable, is an abstract idea that can be measured and data can be taken. In the atmosphere, there are many things or qualities of the atmosphere that can be measured. Rain, which can be observed, or seen anywhere and anytime was one of the first ones to be measured historically. Also, two other accurately measured qualities were wind and humidity. Neither of these can be seen, but can be felt. The devices to measure these three sprang up in the mid-1400s[14] and were respectively the rain gauge, the anemometer, and the hygrometer.[15]
Surface measurements are important data sets to meteorologists. They give a snapshot of a variety of weather conditions at one single location, and are usually at a weather station. The measurements taken at a weather station can include any number of atmospheric observables. Usually, temperature, pressure, wind measurements, and humidity are the variables that are typically measured by a thermometer, barometer, anemometer, and hygrometer, respectively.
Remote sensing, as used in Meteorology, is simply the concept of collecting data from remote weather events and subsequently producing weather information. The common types of remote sensing are Radar, Lidar, and satellites (or photogrammetry). Each passively collects data about the atmosphere from a remote location and, usually, stores the data where the instrument is located. However, some argue that both RADAR and LIDAR are not passive because both use EM radiation to illuminate a specific portion of the atmosphere.[16] On the other hand, anyone has yet to provide verifiable information that exclude these two methods from the passive category.
The 1960 launch of the first successful weather satellite, TIROS-1, marked the beginning of the age where weather information is available globally. Weather satellites along with more general-purpose Earth-observing satellites circling the earth at various altitudes have become an indispensable tool for studying a wide range of phenomena from forest fires to El Niño.
In recent years, climate models have been developed that feature a resolution comparable to older weather prediction models. These climate models are used to investigate long-term climate shifts, such as what effects might be caused by human emission of greenhouse gases.
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Although meteorologists now rely heavily on computer models (numerical weather prediction), it is still relatively common to use techniques and conceptual models that were developed before computers were powerful enough to make predictions accurately or efficiently (generally speaking, prior to around 1980). Many of these methods are used to determine how much skill a forecaster has added to the forecast (for example, how much better than persistence or climatology did the forecast do?). Similarly, they could also be used to determine how much skill the industry as a whole has gained with emerging technologies and techniques.
The persistence method assumes that conditions will not change. Often summarised as "Tomorrow equals today". This method works best over short periods of time in stagnant weather regimes.
The extrapolation method assumes that atmospheric systems will propagate at similar speeds in the near future to those seen in the past. This method achieves the best results when diurnal changes in the pressure and precipitation patterns are taken into account.
The numerical weather prediction or NWP[18] method uses computers to take into account a large number of variables and creates a computer model of the atmosphere. This is most successful when used with the methods below, and when model biases and relative skill are taken into account. In general, the ECMWF model outperforms the NCEP ensemble mean, which outperforms the UKMET/GFS model after 72 hours, which outperform in the NAM model at most time frames. This performance changes when tropical cyclones are taken into account, as the ECMWF/model ensemble methods/model consensus/GFS/UKMET/NOGAPS/ all perform exceedingly well, with the NAM and Canadian GEM exhibiting lower accuracy.
Statistically, it is difficult to beat the mean solution, and the consensus and ensemble methods of forecasting take advantage of the situation by only favoring models that have the greatest support with their ensemble means or other pieces of global model guidance. A local Hydrometeorological Prediction Center study showed that using this method alone verifies 50-55% of the time.
The trends method involves determining the change in fronts and high and low pressure centers in the model runs over various lengths of time. If the trend is seen over a long enough time frame (24 hours or so), it is more meaningful. The forecast models have been known to overtrend however, so use of this method verifies 55-60% the time, more so in the surface pattern than aloft.
The 'climatology or analog method involves using historical weather data collected over long periods of time (years) to predict conditions on a given date. A variation on this theme is the use of teleconnections, which rely upon the date and the expected position of other positive or negative 500 hPa height anomalies to give someone an impression of what the overall pattern would look like with this anomaly in place, and is of more significant help than a model trend since it verifies roughly 75 percent of the time, when used properly and with a stable anomaly center. Another variation is the use of standard deviations from climatology in various meteorological fields. Once the pattern deviates more than 4-5 sigmas from climatology, it becomes an improbable solution.
Madden-Julian oscillation ENSO Walker circulation
| Meteorological data and variables |
|---|
| Atmospheric pressure · Baroclinity · Cloud · Convection · CAPE · CIN · Dew point · Heat index · Humidex · Humidity · Lifted index · Lightning · Pot T · Precipitation · Sea surface temperature · Surface solar radiation · Surface weather analysis · Temperature · Theta-e · Visibility · Vorticity · Wind chill · Water vapor · Wind |
| Meteorological instrumentation and equipment (Earth based) |
|---|
| Anemometer | Barograph | Barometer | Ceiling balloon | Ceiling projector | Ceilometer | Dark adaptor goggles | |
