Meteorological

Information about Meteorological

For the stellar phenomena, see: Meteor

Atmospheric sciences ]
Meteorology ]] weather ]] tropical cyclones ]]
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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.

Meteorology subclassifications

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

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

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]

NOAA: Synoptic scale weather analysis.

Synoptic scale meteorology

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]

Annual mean sea surface temperatures.

Global scale meteorology

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

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

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]

Agricultural meteorology

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

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]

History of meteorology

Main article: Timeline of meteorology

Observation networks and weather forecasting

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.

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

A meteorologist at the console of the IBM 7090 in the Joint Numerical Weather Prediction Unit. c. 1965

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, 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.

Meteorological equipment

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

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.

Satellite image of Hurricane Hugo with a polar low visible at the top of the image.

Remote sensing

Main article: Remote sensing and Radar and satellite imaging

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.

Satellite observation

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.

Weather forecasting

Main article: Weather forecasting

An NWS meteorologist communicates with storm spotters during a severe weather event.


Part of the Nature series on Weather
Seasons
Temperate
• Spring • Summer • • Autumn • Winter •
Tropical
• Dry season • • Wet season
Storms
• Thunderstorm • Tornado • • Tropical Cyclone (Hurricane) • • Winter storm • Blizzard
Precipitation
• Fog • Drizzle • Rain • • Freezing rain • Sleet • • Hail • Snow
Topics
• Meteorology • • Weather forecasting • • Climate • Air pollution •
Project • • [ e]

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.

Persistence method^[17]

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.

Extrapolation method

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.

Numerical forecasting method

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.

Consensus/ensemble methods of forecasting

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.

Trends method^[19]

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.

Climatology/Analog method^[20]

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.

Atmospheric dynamics

Main article: Atmospheric dynamics

Main article: Atmospheric thermodynamics

Atmospheric layers

Main article: Atmospheric layers

Atmospheric circulation

Main article: Atmospheric circulation

Atmospheric patterns and oscillations

Madden-Julian oscillation ENSO Walker circulation

Atmospheric modelling

Main article: Atmospheric models

Observational meteorology

Meteorological topics and phenomena

Links to other keywords in meteorology

Institutions of meteorology/atmospheric science

References and notes

1. ^ "Meteorology." The Encyclopedia Brintannica.15th Ed. 2005.
2. ^ Byers,Horace. General Meteorology. Newy York: McGraw-Hill,1994.
3. ^ Garratt, J.R., The atmospheric boundary layer'', Cambridge University Press, 1992; ISBN 0-521-38052-9.
4. ^ Online Glossary of Meteorology, American Meteorological Society [1] ,2nd Ed., 2000, Allen Press.
5. ^ Bluestein, H., Synoptic-Dynamic Meteorology in Midlatitudes: Principles of Kinematics and Dynamics, Vol. 1, Oxford University Press, 1992; ISBN 0-19-506267-1
6. ^ Global Modelling, US Naval Research Laboratory, Monterrey, Ca.
7. ^ Holton, J.R. [2004]. An Introduction to Dynamic Meteorology, 4th Ed., Burlington, Md: Elsevier Inc.. ISBN 0-12-354015-1.
8. ^ An international version called the Aeronautical Information Publication contains parallel information, as well as specific information on the international airports for use by the international community.
9. ^ "7-1-22. PIREPs Relating to Airframe Icing", [February 16, 2006], Aeronautical Information Manual, FAA AIM Online
10. ^ Agricultural and Forest Meteorology, Elsevier,ISSN: 0168-1923.
11. ^ Encyclopedia Britannica, 2007.
12. ^ About the HPC, NOAA/ National Weather Service, National Centers for Environmental Prediction, Hydrometeorological Prediction Center, Camp Springs, Maryland, 2007.
13. ^ [2]
14. ^ See Timeline of meteorology.
15. ^ It should be noted that many attempts had been made prior to the 1400s to construct adequate equipment to measure the many atmospheric variables. Many were faulty in some way or were simply not reliable. Even Aristotle notes this in some of his work; as the difficulty to measure the air.
16. ^ Peebles, Peyton, [1998], Radar Principles, John Wiley & Sons, Inc., New York, ISBN 0-471-25205-0.
17. ^ The Online Meteorology Guide, Module:Weather Forecasting; Department of Atmospheric Sciences (DAS) at the University of Illinois at Urbana-Champaign.
18. ^ The Online Meteorology Guide
19. ^ The Online Meteorology Guide
20. ^ The Online Meteorology Guide

Books and publications

Byers,Horace. General Meteorology. Newy York: McGraw-Hill,1994.

External links

Please see weather forecasting for weather forecast sites.

Air Quality Meteorology - Online course that introduces the basic concepts of meteorology and air quality necessary to understand meteorological computer models. Written at a bachelor's degree level.
The GLOBE Program - (Global Learning and Observations to Benefit the Environment) An international environmental science and education program that links students, teachers, and the scientific research community in an effort to learn more about the environment through student data collection and observation.
Glossary of Meteorology - From the American Meteorological Society, an excellent reference of nomenclature, equations, and concepts for the more advanced reader.
JetStream - An Online School for Weather - National Weather Service
Learn About Meteorology - Australian Bureau of Meteorology
Meteorology Education and Training (MetEd) - The COMET Program
NOAA Central Library - National Oceanic & Atmospheric Administration
The World Weather 2010 Project The University of Illinois at Urbana-Champaign
NOAA Weather Navigator Plot and download archived data from thousands of worldwide weather stations
Ogimet - online data from meteorological stations of the world, obtained through NOAA free services

Satellite imagery:

Geostationary Satellite Imagery - NOAA National Environmental Satellite, Data, and Information Service
Satellite Imagery - UK Met Office

Base Reflectivity (Radar):

Meteorology during Solar Eclipse

Solar Eclipse Meteorological Measurement

Games;

METEOR (Metric for Evaluation of Translation with Explicit ORdering) is a metric for the evaluation of machine translation output. The metric is based on the harmonic mean of unigram precision and recall, with recall weighted higher than precision.
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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 on these other systems.
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weather is the set of all extant phenomena in a given atmosphere at a given time. The term usually refers to the activity of these phenomena over short periods (hours or days), as opposed to the term climate, which refers to the average atmospheric conditions over longer periods of
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tropical cyclone is a meteorological term for a storm system characterized by a low pressure system center and thunderstorms that produces strong wind and flooding rain. A tropical cyclone feeds on the heat released when moist air rises and the water vapor it contains condenses.
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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.
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Climate is the average and variations of weather over long periods of time. Climate zones can be defined using parameters such as temperature and rainfall.
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Climate change refers to the variation in the Earth's global climate or in regional climates over time. It describes changes in the variability or average state of the atmosphere over time scales ranging from decades to millions of years.
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Interdisciplinarity is the act of drawing from and integrating two or more academic disciplines, professions, technologies, departments, their methods and insights, in the pursuit of a common goal.
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Earth's atmosphere is a layer of gases surrounding the planet Earth and retained by the Earth's gravity. It contains roughly (by molar content/volume) 78% nitrogen, 20.95% oxygen, 0.93% argon, 0.
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A meteorological phenomenon is a weather event which can be explained by the principles of meteorology.

Air mass
Anticyclone
Arctic cyclone
Clouds
Crow Instability
Drought
Dust devil
Dust storm
Extratropical cyclone
Föhn wind
Hail

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EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001. Their greatest hit, their debut single "time after time", peaked at #13 in the Oricon singles chart.
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trillion fold).]]

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. Temperature is one of the principal parameters of thermodynamics.
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Pressure (symbol: p) is the force per unit area applied on a surface in a direction perpendicular to that surface.

Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.
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Water vapor or water vapour (see spelling differences), also aqueous vapor, is the gas phase of water. Water vapor is one state of the water cycle within the hydrosphere.
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not to scale.]]

The troposphere is the lowest portion of Earth's atmosphere. It contains approximately 75% of the atmosphere's mass and almost all of its water vapor and aerosols.

The average depth of the troposphere is about 11 km in the middle latitudes.
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Atmospheric physics is the application of physics to the study of the atmosphere. Atmospheric physicists attempt to model Earth's atmosphere and the atmospheres of the other planets using fluid flow equations, chemical models, radiation balancing, and energy transfer processes in
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Atmospheric chemistry is a branch of atmospheric science in which the chemistry of the Earth's atmosphere and that of other planets is studied. It is a multidisciplinary field of research and draws on environmental chemistry, physics, meteorology, computer modeling, oceanography,
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Hydrology (from Greek: Yδωρ, hudōr, "water"; and λόγος, logos, "knowledge") is the study of the movement, distribution, and quality of water throughout the Earth, and thus addresses both the hydrologic cycle and water resources.
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Hydrometeorology is a branch of meteorology and hydrology that studies the transfer of water and energy between the land surface and the lower atmosphere.

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