HistoryThe ability to predict rains and floods based on annual cycles was evidently used by humans at least from the time of agricultural settlement if not earlier. Early approaches to predicting weather were based on and were practiced by priests. inscriptions on ian tablets included associations between thunder and rain. The s differentiated the and s. Ancient Indian contain mentions of clouds and s. The Samaveda mentions sacrifices to be performed when certain phenomena were noticed. 's classical work ''Brihatsamhita'', written about 500 AD, provides evidence of weather observation. In 350 BC, wrote '. Aristotle is considered the founder of meteorology. One of the most impressive achievements described in the ''Meteorology'' is the description of what is now known as the . The book (composed before 250 BC or between 350 and 200 BC) noted: :If the flashing body is set on fire and rushes violently to the Earth it is called a thunderbolt; if it is only half of fire, but violent also and massive, it is called a ''meteor''; if it is entirely free from fire, it is called a smoking bolt. They are all called 'swooping bolts' because they swoop down upon the Earth. Lightning is sometimes smoky, and is then called 'smoldering lightning"; sometimes it darts quickly along, and is then said to be ''vivid''. At other times, it travels in crooked lines, and is called ''forked lightning''. When it swoops down upon some object it is called 'swooping lightning'. The scientist compiled a book on weather forecasting, called the ''Book of Signs''. The work of Theophrastus remained a dominant influence in the study of weather and in weather forecasting for nearly 2,000 years. In 25 AD, , a geographer for the , formalized the climatic zone system. According to Toufic Fahd, around the 9th century, wrote the ''Kitab al-Nabat'' (''Book of Plants''), in which he deals with the application of meteorology to during the . He describes the meteorological character of the sky, the s and s, the and , the s indicating s and rain, the ''anwa'' ( of rain), and atmospheric phenomena such as winds, thunder, lightning, snow, floods, valleys, rivers, lakes. Early attempts at predicting weather were often related to prophecy and divining, and were sometimes based on astrological ideas. Admiral FitzRoy tried to separate scientific approaches from prophetic ones.
Research of visual atmospheric phenomenaPtolemy wrote on the of light in the context of astronomical observations. In 1021, showed that atmospheric refraction is also responsible for ; he estimated that twilight begins when the sun is 19 degrees below the , and also used a geometric determination based on this to estimate the maximum possible height of the as 52,000 ''passim'' (about 49 miles, or 79 km). was the first to propose that each drop of falling rain had the form of a small sphere, and that this form meant that the rainbow was produced by light interacting with each raindrop. was the first to calculate the angular size of the rainbow. He stated that a rainbow summit can not appear higher than 42 degrees above the horizon. In the late 13th century and early 14th century, and were the first to give the correct explanations for the primary phenomenon. went further and also explained the secondary rainbow. In 1716, Edmund Halley suggested that e are caused by "magnetic effluvia" moving along the lines.
Instruments and classification scalesIn 1441, 's son, Prince Munjong of Korea, invented the first standardized . These were sent throughout the of as an official tool to assess land taxes based upon a farmer's potential harvest. In 1450, developed a swinging-plate , and was known as the first ''anemometer''. In 1607, constructed a . In 1611, wrote the first scientific treatise on snow crystals: "Strena Seu de Nive Sexangula (A New Year's Gift of Hexagonal Snow)." In 1643, invented the mercury . In 1662, Sir invented the mechanical, self-emptying, tipping bucket rain gauge. In 1714, created a reliable scale for measuring temperature with a mercury-type thermometer. In 1742, , a Swedish astronomer, proposed the "centigrade" temperature scale, the predecessor of the current scale. In 1783, the first hair was demonstrated by . In 1802–1803, wrote ''On the Modification of Clouds'', in which he assigns Latin names. In 1806, introduced his . Near the end of the 19th century the first es were published, including the ', which has remained in print ever since. The April 1960 launch of the first successful , , marked the beginning of the age where weather information became available globally.
Atmospheric composition researchIn 1648, rediscovered that decreases with height, and deduced that there is a vacuum above the atmosphere. In 1738, published ''Hydrodynamics'', initiating the and established the basic laws for the theory of gases. In 1761, discovered that ice absorbs heat without changing its temperature when melting. In 1772, Black's student discovered , which he called ''phlogisticated air'', and together they developed the . In 1777, discovered and developed an explanation for combustion. In 1783, in Lavoisier's essay "Reflexions sur le phlogistique," he deprecates the phlogiston theory and proposes a . In 1804, Sir observed that a matte black surface radiates heat more effectively than a polished surface, suggesting the importance of . In 1808, defended caloric theory in ''A New System of Chemistry'' and described how it combines with matter, especially gases; he proposed that the of gases varies inversely with . In 1824, analyzed the efficiency of s using caloric theory; he developed the notion of a and, in postulating that no such thing exists in nature, laid the foundation for the .
Research into cyclones and air flowIn 1494, experienced a tropical cyclone, which led to the first written European account of a hurricane. In 1686, presented a systematic study of the and s and identified solar heating as the cause of atmospheric motions. In 1735, an ''ideal'' explanation of through study of the was written by . In 1743, when was prevented from seeing a lunar eclipse by a , he decided that cyclones move in a contrary manner to the winds at their periphery. Understanding the kinematics of how exactly the rotation of the Earth affects airflow was partial at first. Gaspard-Gustave Coriolis published a paper in 1835 on the energy yield of machines with rotating parts, such as waterwheels. In 1856, proposed the existence of a in the mid-latitudes, and the air within deflected by the Coriolis force resulting in the prevailing westerly winds. Late in the 19th century, the motion of air masses along s was understood to be the result of the large-scale interaction of the and the deflecting force. By 1912, this deflecting force was named the Coriolis effect. Just after World War I, a group of meteorologists in Norway led by developed the that explains the generation, intensification and ultimate decay (the life cycle) of , and introduced the idea of , that is, sharply defined boundaries between es. The group included (who was the first to explain the large scale atmospheric flow in terms of ), (who first determined how rain forms) and .
Observation networks and weather forecastingIn the late 16th century and first half of the 17th century a range of meteorological instruments were invented – the , , , as well as wind and rain gauges. In the 1650s natural philosophers started using these instruments to systematically record weather observations. Scientific academies established weather diaries and organised observational networks. In 1654, established the first ''weather observing'' network, that consisted of meteorological stations in , , , , , , , , Paris and . The collected data were sent to Florence at regular time intervals. In the 1660s of the sponsored networks of weather observers. ' treatise ''Airs, Waters, and Places'' had linked weather to disease. Thus early meteorologists attempted to correlate weather patterns with epidemic outbreaks, and the climate with public health. During the meteorology tried to rationalise traditional weather lore, including astrological meteorology. But there were also attempts to establish a theoretical understanding of weather phenomena. and tried to explain . They reasoned that the rising mass of heated equator air is replaced by an inflow of cooler air from high latitudes. A flow of warm air at high altitude from equator to poles in turn established an early picture of circulation. Frustration with the lack of discipline among weather observers, and the poor quality of the instruments, led the early modern to organise large observation networks. Thus by the end of the 18th century, meteorologists had access to large quantities of reliable weather data. In 1832, an electromagnetic telegraph was created by . The arrival of the in 1837 afforded, for the first time, a practical method for quickly gathering s from 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 began to establish an observation network across the United States under the leadership of . Similar observation networks were established in Europe at this time. The Reverend was key in understanding of cirrus clouds and early understandings of s. , known as 'CKM' Douglas read Ley's papers after his death and carried on the early study of weather systems. Nineteenth century researchers in meteorology were drawn from military or medical backgrounds, rather than trained as dedicated scientists. In 1854, the United Kingdom government appointed to the new office of ''Meteorological Statist to the Board of Trade'' with the task of gathering weather observations at sea. FitzRoy's office became the in 1854, the second oldest national meteorological service in the world (the (ZAMG) in Austria was founded in 1851 and is the oldest weather service in the world). The first daily weather forecasts made by FitzRoy's Office were published in ' 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. The (1875) was established to follow tropical cyclone and . The Finnish Meteorological Central Office (1881) was formed from part of Magnetic Observatory of . Japan's Tokyo Meteorological Observatory, the forerunner of the , began constructing surface weather maps in 1883. The (1890) was established under the . The (1906) was established by a Meteorology Act to unify existing state meteorological services.
Numerical weather predictionIn 1904, Norwegian scientist first argued in his paper ''Weather Forecasting as a Problem in Mechanics and Physics'' that it should be possible to forecast weather from calculations based upon . It was not until later in the 20th century that advances in the understanding of atmospheric physics led to the foundation of modern . In 1922, published "Weather Prediction By Numerical Process," after finding notes and derivations he worked on as an ambulance driver in World War I. He described how small terms in the prognostic fluid dynamics equations that govern atmospheric flow could be neglected, and a numerical calculation scheme that could be devised to allow predictions. Richardson envisioned a large auditorium of thousands of people performing the calculations. However, the sheer number of calculations required was too large to complete without electronic computers, and the size of the grid and time steps used in the calculations led to unrealistic results. Though numerical analysis later found that this was due to . Starting in the 1950s, forecasts with computers became feasible. The first s derived this way used (single-vertical-level) models, and could successfully predict the large-scale movement of midlatitude s, that is, the pattern of and . In 1959, the UK Meteorological Office received its first computer, a . In the 1960s, the nature of the atmosphere was first observed and mathematically described by , founding the field of . These advances have led to the current use of in most major forecasting centers, to take into account uncertainty arising from the chaotic nature of the atmosphere. Mathematical models used to predict the long term weather of the Earth (s), have been developed that have a resolution today that are as coarse as the older weather prediction models. These climate models are used to investigate long-term shifts, such as what effects might be caused by human emission of es.
MeteorologistsMeteorologists are scientists who study and work in the field of meteorology. The American Meteorological Society publishes and continually updates an authoritative electronic ''Meteorology Glossary''. Meteorologists work in , private consulting and services, industrial enterprises, utilities, radio and , and in . In the United States, meteorologists held about 10,000 jobs in 2018. Although weather forecasts and warnings are the best known products of meteorologists for the public, s on radio and television are not necessarily professional meteorologists. They are most often with little formal meteorological training, using unregulated titles such as ''weather specialist'' or ''weatherman''. The and issue "Seals of Approval" to weather broadcasters who meet certain requirements but this is not mandatory to be hired by the media.
EquipmentEach science has its own unique sets of laboratory equipment. 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 atmospheric qualities measured historically. Also, two other accurately measured qualities are wind and humidity. Neither of these can be seen but can be felt. The devices to measure these three sprang up in the mid-15th century and were respectively the , the anemometer, and the hygrometer. Many attempts had been made prior to the 15th century to construct adequate equipment to measure the many atmospheric variables. Many were faulty in some way or were simply not reliable. Even noted this in some of his work as the difficulty to measure the air. Sets of surface measurements are important data to meteorologists. They give a snapshot of a variety of weather conditions at one single location and are usually at a , a ship or a . The measurements taken at a weather station can include any number of atmospheric observables. Usually, temperature, , wind measurements, and are the variables that are measured by a thermometer, barometer, anemometer, and hygrometer, respectively. Professional stations may also include air quality sensors (, , , , , and ), (cloud ceiling), falling precipitation sensor, , , (s, s, ), // (IR/Vis/UV ), /, (, , ), (s and tremors), (visibility), and a for . Upper air data are of crucial importance for weather forecasting. The most widely used technique is launches of s. Supplementing the radiosondes a is organized by the . , as used in meteorology, is the concept of collecting data from remote weather events and subsequently producing weather information. The common types of remote sensing are , , and s (or ). Each collects data about the atmosphere from a remote location and, usually, stores the data where the instrument is located. Radar and Lidar are not passive because both use to illuminate a specific portion of the atmosphere. 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 .
Spatial scalesThe study of the atmosphere can be divided into distinct areas that depend on both time and spatial scales. At one extreme of this scale is climatology. In the timescales of hours to days, meteorology separates into micro-, meso-, and synoptic scale meteorology. Respectively, the size of each of these three scales relates directly with the appropriate timescale. Other subclassifications are used to describe the unique, local, or broad effects within those subclasses.
MicroscaleMicroscale meteorology is the study of atmospheric phenomena on a scale of about or less. Individual thunderstorms, clouds, and local turbulence caused by buildings and other obstacles (such as individual hills) are modeled on this scale.
MesoscaleMesoscale meteorology is the study of atmospheric phenomena that has horizontal scales ranging from 1 km to 1000 km and a vertical scale that starts at the Earth's surface and includes the atmospheric boundary layer, troposphere, , and the lower section of the . Mesoscale timescales last from less than a day to multiple weeks. The events typically of interest are s, s, , in and s, and topographically generated weather systems such as mountain waves and .
Synoptic scaleSynoptic scale meteorology predicts atmospheric changes at scales up to 1000 km and 105 sec (28 days), in time and space. At the synoptic scale, the acting on moving air masses (outside of the tropics) plays a dominant role in predictions. The phenomena typically described by include events such as extratropical cyclones, baroclinic troughs and ridges, , and to some extent s. All of these are typically given on s for a specific time. The minimum horizontal scale of synoptic phenomena is limited to the spacing between .
Global scaleGlobal scale meteorology is the study of weather patterns related to the transport of heat from the to the . Very large scale oscillations are of importance at this scale. These oscillations have time periods typically on the order of months, such as the , or years, such as the and the . Global scale meteorology pushes into the range of climatology. The traditional definition of climate is pushed into larger timescales and with the understanding of the longer time scale global oscillations, their effect on climate and weather disturbances can be included in the synoptic and mesoscale timescales predictions. Numerical Weather Prediction is a main focus in understanding air–sea interaction, tropical meteorology, atmospheric predictability, and tropospheric/stratospheric processes. The in Monterey, California, developed a global atmospheric model called (NOGAPS). NOGAPS is run operationally at for the United States Military. Many other global atmospheric models are run by national meteorological agencies.
Some meteorological principles
Boundary layer meteorologymeteorology is the study of processes in the air layer directly above Earth's surface, known as the (ABL). The effects of the surface – heating, cooling, and – cause within the air layer. Significant movement of , , or on time scales of less than a day are caused by turbulent motions. Boundary layer meteorology includes the study of all types of surface–atmosphere boundary, including ocean, lake, urban land and non-urban land for the study of meteorology.
Dynamic meteorologyDynamic meteorology generally focuses on the of the atmosphere. The idea of 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.
Weather forecastingWeather forecasting is the application of science and technology to predict the state of the at a future time and given location. Humans have attempted to predict the weather informally for millennia and formally since at least the 19th century. Weather forecasts are made by collecting quantitative about the current state of the atmosphere and using scientific understanding of atmospheric processes to project how the atmosphere will evolve. Once an all-human endeavor based mainly upon changes in , current weather conditions, and sky condition, are now used to determine future conditions. Human input is still required to pick the best possible forecast model to base the forecast upon, which involves pattern recognition skills, s, knowledge of model performance, and knowledge of model biases. The nature of the atmosphere, the massive computational power required to solve the equations that describe the atmosphere, error involved in measuring the initial conditions, and an incomplete understanding of atmospheric processes mean that forecasts become less accurate as the difference in current time and the time for which the forecast is being made (the ''range'' of the forecast) increases. The use of ensembles and model consensus help narrow the error and pick the most likely outcome. There are a variety of end uses to weather forecasts. Weather warnings are important forecasts because they are used to protect life and property. Forecasts based on temperature and are important to agriculture, and therefore to commodity traders within stock markets. Temperature forecasts are used by utility companies to estimate demand over coming days. On an everyday basis, people use weather forecasts to determine what to wear. Since outdoor activities are severely curtailed by heavy rain, snow, and , forecasts can be used to plan activities around these events, and to plan ahead and survive them.
Aviation meteorologyAviation meteorology deals with the impact of weather on . 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 ':
''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.''
Agricultural meteorologyMeteorologists, , agricultural hydrologists, and are people concerned with studying the effects of weather and climate on plant distribution, , water-use efficiency, 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.
Hydrometeorologyis the branch of meteorology that deals with the , the water budget, and the rainfall statistics of s. 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. The multidisciplinary nature of the branch can result in technical challenges, since tools and solutions from each of the individual disciplines involved may behave slightly differently, be optimized for different hard- and software platforms and use different data formats. There are some initiatives – such as the DRIHM project – that are trying to address this issue.
Nuclear meteorologyNuclear meteorology investigates the distribution of s and es in the atmosphere.
Maritime meteorologyMaritime meteorology deals with air and wave forecasts for ships operating at sea. Organizations such as the , Honolulu forecast office, United Kingdom , and prepare high seas forecasts for the world's oceans.
Military meteorologyMilitary meteorology is the research and application of meteorology for purposes. In the United States, the 's oversees meteorological efforts for the Navy and while the 's is responsible for the Air Force and .
Environmental meteorologyEnvironmental meteorology mainly analyzes industrial pollution dispersion physically and chemically based on meteorological parameters such as temperature, humidity, wind, and various weather conditions.
Renewable energyMeteorology applications in renewable energy includes basic research, "exploration," and potential mapping of wind power and solar radiation for wind and solar energy.
Further reading*Byers, Horace. General Meteorology. New York: McGraw-Hill, 1994. * * * * * * *
Dictionaries and encyclopedias* * *
External links''Please see for weather forecast sites.''