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History of meteorology Early achievements in meteorology The term meteorology comes from Aristotle's Meteorology. Although the term meteorology is used today to describe a subdiscipline of the atmospheric sciences, Aristotle's work is more general. The work touches upon much of what is known as the earth sciences. In his own words: ...all the affections we may call common to air and water, and the kinds and parts of the earth and the affections of its parts. One of the most impressive achievements in Meteorology is his description of what is now known as the hydrologic cycle: Now the sun, moving as it does, sets up processes of change and becoming and decay, and by its agency the finest and sweetest water is every day carried up and is dissolved into vapour and rises to the upper region, where it is condensed again by the cold and so returns to the earth. Galileo Galilei constructs a thermoscope. Not only did this device measure temperature, but it represented a paradigm shift. Up to this point, heat and cold were believed to be qualities of Aristotle's elements (fire, water, air, and earth). Note: There is some controversy about who actually built this first thermoscope. There is some evidence for this device being independently built at several different times. This is the era of the first recorded meteorological observations. As there was no standard measurement, they were of little use until the work of Daniel Gabriel Fahrenheit and Anders Celsius in the 18th century. Evangelista Torricelli, a contemporary and one-time assistant of Galileo, creates the first man-made sustained vacuum in 1643, and in the process creates the first barometer. Changes in height of mercury in this Toricelli Tube lead to his discovery that atmospheric pressure changes over time. Blaise Pascal discovers that atmospheric pressure decreases with height, and deduces that there is a vacuum above the atmosphere. Robert Hooke builds an anemometer to measure windspeed. Edmund Halley maps the trade winds, deduces that atmospheric changes are driven by solar heat, and confirms the discoveries of Pascal about atmospheric pressure. George Hadley is the first to take the rotation of the Earth into account to explain the behavior of the trade winds. Although the mechanism Hadley described was incorrect, predicting trade winds half as strong as the actual winds, the circulating cells that Hadley described later become known as Hadley cells. Benjamin Franklin observes that weather systems in North America move from west to east, demonstrates that lightning is electricity, publishes the first scientific chart of the Gulf Stream, links a volcanic eruption to weather, and speculates about the effect of deforestation on climate. Horace de Saussure constructs a hair hygrometer to measure humidity. Luke Howard writes On the Modification of Clouds in which he assigns cloud types Latin names. Francis Beaufort introduces his system for classifying wind speeds. Controversial Law of Storms work by William Reid , which splits meteorological establishment into two camps in regard to low pressure systems. It would take over ten years of debate to finally come to a consensus on the behavior of low pressure systems. Elias Loomis the first person known to attempt to devise a theory on frontal zones. This idea did not catch on until expanded upon by the Norwegians in the years following World War I. Observation networks and weather forecasting The arrival of the electrical telegraph in 1837 afforded, for the first time, a practical method for gathering quickly information on surface weather conditions from over a wide area. These 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 Smithsonian Institute began to establish an observation network across the United States under the leadership of Joseph Henry . Similar observation networks were established in Europe at this time. In 1854, the United Kingdom gorvernment 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 become 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. The Coriolis effect 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. Numerical weather prediction In 1904 the Norwegian scientist Vilhelm Bjerknes first postulated that prognostication of the weather is possible from calculation 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, numerical experiments with computers became feasible. The first weather forecasts derived this way used barotropic (that means, single-vertical-level) models, and could successfully predict the large-scale movement of midlatitude Rossby waves, that is, the pattern of atmospheric lows and highs. 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. Satellite observation In 1960, the launch of TIROS-1, the first successful weather satellite 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. Weather forecasting 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. Meteorology and climatology With the development of powerful new supercomputers like the Earth Simulator in Japan, mathematical modeling of the atmosphere can reach unprecedented accuracy. This is not only due to the enhanced spatial and temporal resolution of the grids employed, but also because these more powerful machines can model the Earth as an integrated climate system, where atmosphere, ocean, vegetation, and man-made influences depend on each other realistically. The goal in global meteorological modeling can be termed Earth System Modeling, with a growing number of models of various processes coupled to each other. Predictions for global effects like Global Warming and El Niño are expected to benefit substantially from these advancements. Regional models are attracting more interest as the resolution of global models increases. With regional weather disasters such as the Elbe flooding in 2002 and the European heat wave in 2003, decision makers expect from these models accurate assessments about the possible increase of these natural hazards in a specific region. Countermeasures such as dikes or intentional flooding might be effective in preventing or at least attenuating natural hazards. For models at all scales, increased model resolution means less reliance on parameterizations, which are empirically derived expressions for processes that cannot be resolved on the model grid. For example, in mesoscale models individual clouds can now be resolved, removing the need for formulations that average over a grid box. In global modeling, atmospheric waves such as gravity waves with short temporal and spatial scales can be represented without resorting to often overly simplified parameterizations. Meteorological topics and phenomena Institutions of meteorology/atmospheric science | |||||||||
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