Meteorology (from
GreekAncient Greek is the historical stage in the development of the Greek language spanning across the Archaic , Classical , and Hellenistic periods of ancient Greece and the ancient world. It is predated in the 2nd millennium BC by Mycenaean Greek...
,
metéōros, "high in the sky"; and ,
-logia) is the interdisciplinary scientific study of the
atmosphereThe Earth's atmosphere is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention , and reducing temperature extremes between day and night...
that focuses on
weatherWeather is a set of all the phenomena occurring in a given atmosphere at a given time. Weather phenomena lie in the troposphere. Weather refers, generally, to day-to-day temperature and precipitation activity, whereas climate is the term for the average atmospheric conditions over longer periods...
processes and forecasting (in contrast with
climatologyClimatology is the study of climate, scientifically defined as weather conditions averaged over a period of time, and is a branch of the atmospheric sciences...
). Studies in the field stretch back millennia, though significant progress in meteorology did not occur until the eighteenth century. The nineteenth century saw breakthroughs occur after observing networks developed across several countries. Breakthroughs in weather forecasting were achieved in the latter half of the twentieth century, after the development of the computer.
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
EarthEarth is the third planet from the Sun. It is the fifth largest of the eight planets in the solar system, and the largest of the terrestrial planets in the Solar System in terms of diameter, mass and density...
's atmosphere. They are
temperatureIn physics, temperature is a physical property of a system that underlies the common notions of hot and cold; something that feels hotter generally has the higher temperature. Temperature is one of the principal parameters of thermodynamics...
, air pressure,
water vaporWater vapor or water vapour , also aqueous vapor, is the gas phase of water. Water vapor is one state of the water cycle within the hydrosphere. Water vapor can be produced from the evaporation or boiling of liquid water or from the sublimation of ice...
, 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
troposphereThe troposphere is the lowest portion of Earth's atmosphere. It contains approximately 75 percent of the atmosphere's mass and 99 percent of its water vapor and aerosols....
. Different spatial scales are studied to determine how systems on local, region, and global levels impact weather and climatology. Meteorology,
climatologyClimatology is the study of climate, scientifically defined as weather conditions averaged over a period of time, and is a branch of the atmospheric sciences...
,
atmospheric physicsAtmospheric 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 the atmosphere...
, and
atmospheric chemistryAtmospheric 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, geology and...
are sub-disciplines of the
atmospheric sciencesAtmospheric 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. Meteorology includes atmospheric chemistry and atmospheric physics with a major focus on weather...
. Meteorology and
hydrologyHydrology is the study of the movement, distribution, and quality of water throughout Earth, and thus addresses both the hydrologic cycle and water resources...
compose the interdisciplinary field of
hydrometeorologyHydrometeorology is a branch of meteorology and hydrology that studies the transfer of water and energy between the land surface and the lower atmosphere....
. 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, transport, agriculture and construction.
History
In 350 BC,
AristotleAristotle was a Greek philosopher, a student of Plato and teacher of Alexander the Great. He wrote on many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, politics, government, ethics, biology, and zoology.Together with Plato and Socrates , Aristotle is one of...
wrote
MeteorologyMeteorology is a text by Aristotle which contains his theories about the earth sciences. These include early accounts of water evaporation, weather phenomena, and earthquakes....
. Aristotle is considered the founder of meteorology. For 2,000 years, no one added anything significant to his findings (Farrand, 1991). One of the most impressive achievements described in the
Meteorology is the description of what is now known as the hydrologic cycle. The
GreekAncient Greece is the civilisation belonging to the period of Greek history lasting from the Greek Dark Ages ca. 1100 BC and the Dorian invasion, to 146 BC and the Roman conquest of Greece after the Battle of Corinth. It is generally considered to be the seminal culture which provided the...
scientist
TheophrastusTheophrastus , a Greek native of Eressos in Lesbos, was the successor of Aristotle in the Peripatetic school. His interests were wide-ranging, extending from biology and physics to ethics and metaphysics. His two surviving botanical works, Enquiry into Plants and On the Causes of Plants, were an...
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,
Pomponius MelaPomponius Mela, who wrote around AD 43, was the earliest Roman geographer.His little work is a mere compendium, occupying less than one hundred pages of ordinary print, dry in style and deficient in method, but of pure Latinity, and occasionally relieved by pleasing word-pictures...
, a geographer for the
Roman EmpireThe Roman Empire was the post-Republican phase of the ancient Roman civilization, characterised by an autocratic form of government and large territorial holdings in Europe and around the Mediterranean. The term is used to describe the Roman state during and after the time of the first emperor,...
, formalized the climatic zone system. Around the 9th century,
Al-Kindi' , also known to the West by the Latinized version of his name Alkindus, was an Arab Iraqi polymath: an Islamic philosopher, scientist, astrologer, astronomer, cosmologist, chemist, logician, mathematician, musician, physician, physicist, psychologist, and meteorologist...
(Alkindus), an
Arab naturalistIslamic geography includes the advancement of geography, cartography and earth sciences under various Islamic civilizations. During the medieval ages, Islamic geography was driven by a number of factors: the Islamic Golden Age, parallel development of Islamic astronomy, translation of ancient texts...
, wrote a treatise on meteorology entitled
Risala fi l-Illa al-Failali l-Madd wa l-Fazr (
Treatise on the Efficient Cause of the Flow and Ebb), in which he presents an argument on
tideTides are the rises and falls of sea level caused by the combined effect of rotation of the Earth and the gravitation of the Moon and the Sun. The tides occur with a period of approximately 12 and a half hours and are influenced by the shape of the near-shore bottom.Most coastal areas experience...
s which "depends on the changes which take place in bodies owing to the rise and fall of temperature." Also in the 9th century,
Al-DinawariĀbu Ḥanīfah Āḥmad ibn Dawūd Dīnawarī was a Persian polymath excelling as much in astronomy, agriculture, botany and metallurgy and as he did in geography, mathematics and history. He was born in Dinawar,...
, a
KurdishThe Kurds are an Ethnic-Iranian ethnolinguistic group mostly inhabiting a region known as Kurdistan, which includes adjacent parts of Iran, Iraq, Syria, and Turkey...
naturalist, writes the
Kitab al-Nabat (
Book of Plants), in which he deals with the application of meteorology to
agricultureAgriculture is the production of food and goods through farming and forestry. Agriculture was the key development that led to the rise of human civilization, with the husbandry of domesticated animals and plants creating food surpluses that enabled the development of more densely populated and...
during the
Muslim Agricultural RevolutionThe period from 8th century to the 13th century witnessed a fundamental transformation in agriculture known as the Arab Agricultural Revolution, Medieval Green Revolution, Muslim Agricultural Revolution or Islamic Green Revolution...
. He describes the meteorological character of the sky, the
planetA planet , is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.The term planet is ancient, with ties to history, science,...
s and
constellationIn modern astronomy, a constellation is an area of the celestial sphere, defined by exact boundaries.The term "constellation" can also be used loosely to refer to just the more prominent visible stars that seem to form a pattern in that area.-Definitions:...
s, the
sunThe Sun is the star at the center of the Solar System. The Earth and other matter orbit the Sun, which by itself accounts for about 99.86% of the Solar System's mass....
and
moonThe Moon is Earth's only natural satellite and the fifth largest satellite in the Solar System. The average centre-to-centre distance from the Earth to the Moon is , about thirty times the diameter of the Earth. The common centre of mass of the system is located at about —a quarter the Earth's...
, the
lunar phaseA lunar phase or phase of the moon refers to the appearance of the illuminated portion of the Moon as seen by an observer, usually on Earth. The lunar phases vary cyclically as the Moon orbits the Earth, according to the changing relative positions of the Earth, Moon and Sun...
s indicating
seasonA season is a division of the year, marked by changes in weather.Seasons result from the yearly revolution of the Earth around the Sun and the tilt of the Earth's axis relative to the plane of revolution...
s and
rainRain is liquid precipitation, as opposed to other kinds of precipitation such as snow, hail and sleet. On Earth, it is the condensation of atmospheric water vapor into drops heavy enough to fall, often making it to the surface...
, the
anwa (
heavenly bodiesAstronomical objects are significant physical entities, associations or structures which current science has confirmed to exist in outer space. This does not necessarily mean that more current science will not disprove their existence. Some astronomical objects, such as Themis and Neith are, in...
of rain), and atmospheric phenomena such as winds, thunder, lightning, snow, floods, valleys, rivers, lakes, wells and other sources of water.
Research of visual atmospheric phenomena
In 1021, Ibn al-Haytham (Alhazen), an Iraqi scientist writes on the
atmospheric refractionAtmospheric refraction is the deviation of light or other electromagnetic wave from a straight line as it passes through the atmosphere due to the variation in air density as a function of altitude. Atmospheric refraction near the ground produces mirages and can make distant objects appear to...
of
lightLight is electromagnetic radiation, particularly radiation of a wavelength that is visible to the human eye ....
. He showed that the twilight is due to atmospheric refraction and only begins when the Sun is 19 degrees below the
horizonThe horizon is the apparent line that separates earth from sky.It is the line that divides all visible directions into two categories: those that intersect the Earth's surface, and those that do not...
, and uses a complex geometric demonstration to measure the height of the
Earth's atmosphereThe Earth's atmosphere is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention , and reducing temperature extremes between day and night...
as 52,000
passuum , which is very close to the modern measurement of . He also realized that the
atmosphereAn atmosphere is a layer of gases that may surround a material body of sufficient mass, by the gravity of the body, and are retained for a longer duration if gravity is high and the atmosphere's temperature is low...
also reflects light, from his
observationObservation is either an activity of a living being , consisting of receiving knowledge of the outside world through the senses, or the recording of data using scientific instruments. The term may also refer to any datum collected during this activity.-Observation in science:A scientific method...
s of the sky brightening even before the
SunThe Sun is the star at the center of the Solar System. The Earth and other matter orbit the Sun, which by itself accounts for about 99.86% of the Solar System's mass....
rises. In 1121,
Al-KhaziniAbd al-Rahman al-Khazini was a scientist, astronomer, physicist, biologist, alchemist, mathematician and philosopher from Merv, then in the Khorasan province of Persia but now in Turkmenistan, who made important contributions to physics and astronomy. He is considered the greatest scholar from...
, a
Muslim scientistScience in medieval Islam, also known as Islamic science, is a term used in the history of science to refer to the science developed in the Islamic world between the 7th and 16th centuries, a period also known as the Islamic Golden Age. Scientists from the region were also known to develop many...
of
Byzantine GreekByzantine Greeks or Byzantines is a conventional term used by modern historians to refer to the medieval Greek or Hellenized citizens of the Byzantine Empire, centered mainly in Constantinople, the southern Balkans, the Greek islands, Asia Minor and the large urban centres of the Near East and...
descent, publishes the
The Book of the Balance of Wisdom, the first study on the
hydrostatic balanceHydrostatic equilibrium occurs when compression due to gravity is balanced by a pressure gradient wihch creates a pressure gradient force in the opposite direction...
. In the late 13th century and early 14th century,
Qutb al-Din al-ShiraziQotb al-Din Shirazi was a 13th century Persian Muslim polymath and Persian poet who made contributions astronomy, mathematics, medicine, physics, music theory, philosophy and Sufism.- Biography :...
and his student Kamāl al-Dīn al-Fārisī continued the work of Ibn al-Haytham, and they were the first to give the correct explanations for the
rainbowA rainbow is an optical and meteorological phenomenon that causes a spectrum of light to appear in the sky when the Sun shines onto droplets of moisture in the Earth's atmosphere...
phenomenon. In 1716, Edmund Halley suggests that
auroraeAuroras, sometimes called the northern and southern lights or aurorae , are natural light displays in the sky, usually observed at night, particularly in the polar regions. They typically occur in the ionosphere. They are also referred to as polar auroras...
are caused by "magnetic effluvia" moving along the
Earth's magnetic fieldEarth's magnetic field is approximately a magnetic dipole, with the magnetic field S pole near the Earth's geographic north pole and the other magnetic field N pole near the Earth's geographic south pole...
lines.
Instruments and classification scales
In 1441,
King SejongsSejong the Great was the Third king of the Joseon Dynasty of Korea. He is best remembered for creating the Korean alphabet Hangul, despite strong opposition from the scholars educated in hanja...
son, Prince Munjong, invented the first standardized
rain gaugeA rain gauge is a type of instrument used by meteorologists and hydrologists to gather and measure the amount of liquid precipitation over a set period of time.-History:The first known records of rainfalls were kept by the...
. These were sent throughout the
Joseon DynastyJoseon , was a Korean sovereign state founded by Taejo Yi Seong-gye that lasted for approximately five centuries. It was founded in the aftermath of the overthrow of the Goryeo Kingdom at what is today the city of Kaesong...
of
KoreaKorea is a civilization and formerly unified nation currently divided into two states. Located on the Korean Peninsula, it borders China to the northwest, Russia to the northeast, and is separated from Japan to the east by the Korea Strait....
as an official tool to assess land taxes based upon a farmer's potential harvest. In 1450,
Leone Battista AlbertiLeon Battista Alberti was an Italian author, artist, architect, poet, priest, linguist, philosopher, and cryptographer, and general Renaissance humanist polymath...
developed a swinging-plate
anemometerAn anemometer is a device that is used for measuring wind speed, and is one instrument used in a weather station. The term is derived from the Greek word anemos, meaning wind...
, and is known as the first
anemometer. In 1607,
Galileo GalileiGalileo Galilei was an Italian physicist, mathematician, astronomer, and philosopher who played a major role in the Scientific Revolution. His achievements include improvements to the telescope and consequent astronomical observations, and support for Copernicanism...
constructs a
thermoscopeA Galileo thermometer, Galilean thermometer , is a thermometer made of a sealed glass cylinder containing a clear liquid and a series of objects whose densities are designed to sink in sequence as the liquid is warmed and decreases in density and vice-versa.-Typical design:Suspended in the liquid...
. In 1611,
Johannes KeplerJohannes Kepler was a German mathematician, astronomer and astrologer, and key figure in the 17th century scientific revolution. He is best known for his eponymous laws of planetary motion, codified by later astronomers based on his works Astronomia nova, Harmonices Mundi, and Epitome of...
writes the first scientific treatise on snow crystals: "Strena Seu de Nive Sexangula (A New Year's Gift of Hexagonal Snow)". In 1643,
Evangelista TorricelliEvangelista Torricelli was an Italian physicist and mathematician, best known for his invention of the barometer.-Biography:Torricelli was born in Faenza, then part of the Papal States...
invents the mercury
barometerA barometer is an instrument used to measure atmospheric pressure. It can measure the pressure exerted by the atmosphere by using water, air, or mercury. Pressure tendency can forecast short term changes in the weather...
. In 1662, Sir
Christopher WrenSir Christopher Wren was one of the best known and highest acclaimed English architects in history,...
invented the mechanical, self-emptying, tipping bucket rain gauge. In 1714,
Gabriel FahrenheitDaniel Gabriel Fahrenheit was a physicist and engineer who determined a temperature scale now named after him.- Biography :...
creates a reliable scale for measuring temperature with a mercury-type thermometer. In 1742,
Anders CelsiusAnders Celsius was a Swedish astronomer. He was professor of astronomy at Uppsala University from 1730 to 1744, but traveled from 1732 to 1735 visiting notable observatories in Germany, Italy and France. He found the Uppsala Astronomical Observatory in 1741, and in 1742 he proposed the Celsius...
, a Swedish astronomer, proposed the 'centigrade' temperature scale, the predecessor of the current
CelsiusCelsius is a temperature scale that is named after the Swedish astronomer Anders Celsius , who developed a similar temperature scale two years before his death...
scale. In 1783, the first hair
hygrometerHygrometers are instruments used for measuring relative humidity. A simple form of a hygrometer is specifically known as a psychrometer and consists of two thermometers, one of which includes a dry bulb and the other of which includes a bulb that is kept wet to measure wet-bulb temperature...
is demonstrated by
Horace-Bénédict de Saussure200px|thumb|Portrait of Horace-Bénédict de Saussure Horace-Bénédict de Saussure was a Swiss aristocrat, physicist and Alpine traveller, often considered the founder of alpinism.-Life and work:Saussure was born in Conches, near Geneva, in 1740.His early interest in botanical studies led him...
. In 1802-1803,
Luke HowardLuke Howard was a British manufacturing chemist and an amateur meteorologist with broad interests in science...
writes
On the Modification of Clouds in which he assigns
cloud types LatinLatin is an Italic language originally spoken in Latium and Ancient Rome. Through the Roman conquest, Latin spread throughout the Mediterranean and a large part of Europe...
names. In 1806,
Francis BeaufortRear-Admiral Sir Francis Beaufort, FRS, FRGS was an Irish born hydrographer and officer in Britain's Royal Navy. Beaufort was the creator of the Beaufort scale for indicating wind force.-Biography:...
introduced his
system for classifying wind speedsThe Beaufort scale is an empirical measure for describing wind speed based mainly on observed sea conditions. Its full name is the Beaufort wind force scale.-History:...
. Near the end of the
19th centuryThe 19th century was a period in history marked by the collapse of the Spanish, Portuguese, Chinese, Ottoman, Holy Roman and Mughal empires...
the first
cloud atlasA cloud atlas is a pictorial key to the nomenclature of clouds. Early cloud atlases were an important element in the training of meteorologists and in weather forecasting, and the author of a 1923 atlas stated that increasing use of the air as a means of transportation will require and lead to a...
es were published, including the
International Cloud AtlasInternational Cloud Atlas is a cloud atlas first published in 1896 and remaining in print since then. Its initial purposes included to aid in the training of meteorologists and to promote more consistent use of vocabulary describing clouds, both important for early weather forecasting...
, which has remained in print ever since. The April 1960 launch of the first successful
weather satelliteA weather satellite is a type of satellite that is primarily used to monitor the weather and climate of the Earth. Satellites can be either polar orbiting, seeing the same swath of the Earth every 12 hours, or geostationary, hovering over the same spot on Earth by orbiting over the equator while...
,
TIROS-1TIROS I was the first successful weather satellite, and the first of a series of Television Infrared Observation Satellites. It was launched at 6:40 AM EST on April 1, 1960 from Cape Canaveral, Florida, in the United States....
, marked the beginning of the age where weather information became available globally.
Atmospheric composition research
In 1648,
Blaise Pascal Blaise Pascal , was a French mathematician, physicist, and religious philosopher. He was a child prodigy who was educated by his father, a civil servant...
rediscovers that
atmospheric pressureAtmospheric pressure is defined as the force per unit area exerted against a surface by the weight of air above that surface at any given point in the Earth's atmosphere. In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above...
decreases with height, and deduces that there is a vacuum above the atmosphere. In 1738,
Daniel BernoulliDaniel Bernoulli was a Dutch-Swiss mathematician and was one of the many prominent mathematicians in the Bernoulli family. He is particularly remembered for his applications of mathematics to mechanics, especially fluid mechanics, and for his pioneering work in probability and statistics...
publishes
Hydrodynamics, initiating the
kinetic theoryKinetic theory is the theory that gases are made up of a large number of small particles , all of which are in constant, random motion. The rapidly moving particles constantly collide with each other and with the walls of the container...
of gases and established the basic laws for the theory of gases. In 1761,
Joseph BlackJoseph Black was a Scottish physician, physicist, and chemist, known for his discoveries of latent heat, specific heat, and carbon dioxide. He was a founder of thermochemistry who developed many pre-thermodynamics concepts, such as heat capacity, and was the mentor for James Watt...
discovers that
iceIce is a solid phase, usually crystalline, of a non-metallic substance that is liquid or gas at room temperature, such as carbon dioxide ice , ammonia ice, or methane ice. However, the predominant use of the term ice is for water ice, technically restricted to one of the 15 known crystalline phases...
absorbs
heatIn physics and thermodynamics, heat is the process of energy transfer from one body or system due to thermal contact, which in turn is defined as an energy transfer to a body in any other way than due to work performed on the body....
without changing its temperature when melting. In 1772, Black's student
Daniel RutherfordProfessor Daniel Rutherford was a Scottish chemist and physician who is most famous for the isolation of nitrogen in 1772.- Isolation of nitrogen :...
discovers
nitrogenNitrogen is a chemical element that has the symbol N and atomic number 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless and mostly inert diatomic gas at standard conditions, constituting 78% by volume of Earth's atmosphere.Many industrially important...
, which he calls
phlogisticated air, and together they developed the
phlogiston theoryThe phlogiston theory , first stated in 1667 by Johann Joachim Becher, is a defunct scientific theory that posited the existence of a fire-like element called "phlogiston" that was contained within combustible bodies, and released during combustion...
. In 1777,
Antoine LavoisierAntoine-Laurent de Lavoisier ; ), the father of modern chemistry, was a French noble prominent in the histories of chemistry and biology...
discovers
oxygenOxygen Oxygen Oxygen (acid, literally "sharp", from the taste of acids) and -γενής (-genēs) (producer, literally begetter) is the element with atomic number 8 and represented by the symbol O...
and develops an explanation for combustion. In 1783, in Lavoisier's book
Reflexions sur le phlogistique, he deprecates the phlogiston theory and proposes a
caloric theoryThe caloric theory is an obsolete scientific theory that heat consists of a fluid called caloric that flows from hotter to colder bodies. Caloric was also thought of as a weightless gas that could pass in and out of pores in solids and liquids...
. In 1804, Sir
John LeslieSir John Leslie was a Scottish mathematician and physicist best remembered for his research into heat.Leslie gave the first modern account of capillary action in 1802 and froze water using an air-pump in 1810, the first artificial production of ice.In 1804, he experimented with radiant heat using...
observes that a matte black surface radiates heat more effectively than a polished surface, suggesting the importance of black body radiation. In 1808,
John DaltonJohn Dalton FRS was an English chemist, meteorologist and physicist. He is best known for his pioneering work in the development of modern atomic theory, and his research into colour blindness .-Early life:John Dalton was born into a Quaker family at Eaglesfield, near Cockermouth in Cumberland,...
defends caloric theory in
A New System of Chemistry and describes how it combines with matter, especially gases; he proposes that the heat capacity of gases varies inversely with
atomic weightAtomic weight is a dimensionless physical quantity, the ratio of the average mass of atoms of an element to 1/12 of the mass of an atom of carbon-12...
. In 1824,
Sadi CarnotNicolas Léonard Sadi Carnot was a French physicist and military engineer who, in his 1824 Reflections on the Motive Power of Fire, gave the first successful theoretical account of heat engines, now known as the Carnot cycle, thereby laying the foundations of the second law of thermodynamics...
analyzes the efficiency of
steam engineA steam engine is a heat engine that performs mechanical work using steam as its working fluid.The idea of using boiling water to produce mechanical motion has a long history, going back about 2000 years...
s using caloric theory; he develops the notion of a reversible process and, in postulating that no such thing exists in nature, lays the foundation for the
second law of thermodynamicsThe second law of thermodynamics is an expression of the universal principle of entropy, stating that the entropy of an isolated system which is not in equilibrium will tend to increase over time, approaching a maximum value at equilibrium, and that the entropy change dS of a system undergoing any...
.
Research into cyclones and air flow
In 1494,
Christopher ColumbusChristopher Columbus was a navigator, colonizer and explorer whose voyages across the Atlantic Ocean led to general European awareness of the American continents in the Western Hemisphere...
experiences a tropical cyclone, leads to the first written European account of a hurricane. In 1686, Edmund Halley presents a systematic study of the
trade windThe trade winds are the prevailing pattern of easterly surface winds found in the tropics near the Earth's equator. The trade winds blow predominantly from the northeast in the Northern Hemisphere and from the southeast in the Southern Hemisphere...
s and
monsoonA pennis is traditionally defined as a seasonal reversing wind accompanied by seasonal changes in precipitation, but now is used to describe seasonal changes atmospheric circulation and precipitation The major monsoon systems of the world consist of the African and Asia-Australian monsoons...
s and identifies solar heating as the cause of atmospheric motions. In 1735, an
ideal explanation of
global circulationAtmospheric circulation is the large-scale movement of air, and the means by which thermal energy is distributed on the surface of the Earth....
through study of the Trade winds was written by
George HadleyGeorge Hadley was an English lawyer and amateur meteorologist who proposed the atmospheric mechanism by which the Trade Winds are sustained. As a key factor in ensuring that European sailing vessels reached North American shores, understanding the Trade Winds was becoming a matter of great...
. In 1743, when
Benjamin FranklinBenjamin Franklin was one of the Founding Fathers of the United States of America. A noted polymath, Franklin was a leading author and printer, satirist, political theorist, politician, scientist, inventor, civic activist, statesman, soldier, and diplomat...
is prevented from seeing a lunar eclipse by a
hurricaneA tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones feed on heat released when moist air rises, resulting in condensation of water vapor contained in the moist air...
, he decides 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,
William FerrelWilliam Ferrel , an American meteorologist, developed theories which explained the mid-latitude atmospheric circulation cell in detail, and it is after him that the Ferrel cell is named. He was born in southern Pennsylvania. His family moved to what would become West Virginia in 1829...
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. Late in the 19th century the full extent of the large scale interaction of
pressure gradient forceThe pressure gradient force is not actually a 'force' but the acceleration of air due to pressure difference . It is usually responsible for accelerating a parcel of air from a high atmospheric pressure region to a low pressure region, resulting in wind...
and deflecting force that in the end causes air masses to move
along isobarIsobar may refer to:* A contour line of equal or constant pressure in meteorology* Isobar , in nuclear physics, one of multiple nuclides with equal numbers of nucleons* A heat pipe* Isobar , a 2009 science fiction film...
s was understood. By 1912, this deflecting force was named the Coriolis effect. Just after
World War IIWorld War II, or the Second World War , was a global military conflict which involved a majority of the world's nations, including all great powers, organized into two opposing military alliances: the Allies and the Axis...
, a group of meteorologists in
NorwayNorway , officially the Kingdom of Norway, is a country in Northern Europe occupying the western portion of the Scandinavian Peninsula, as well as Jan Mayen and the Arctic archipelago of Svalbard under the Spitsbergen Treaty...
led by
Vilhelm BjerknesVilhelm Friman Koren Bjerknes was a Norwegian physicist and meteorologist who did much to found the modern practice of weather forecasting.-Life & career:...
developed the
Norwegian cyclone modelThe older of the models of extratropical cyclone development is known as the Norwegian Cyclone Model, developed during and shortly after World War I within the Bergen School of Meteorology. In this theory, cyclones develop as they move up and along a frontal boundary, eventually occluding and...
that explains the generation, intensification and ultimate decay (the life cycle) of
mid-latitude cyclonesExtratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are a group of cyclones defined as synoptic scale low pressure weather systems that occur in the middle latitudes of the Earth having neither tropical nor polar characteristics, and are connected with fronts and...
, introducing the idea of fronts, that is, sharply defined boundaries between
air massIn meteorology, an air mass is a large volume of air defined by its temperature and water vapor content. Air masses cover many hundreds or thousands of square miles, and adopt the characteristics of the surface below them. They are classified according to latitude and their continental or...
es. The group included
Carl-Gustaf RossbyCarl-Gustaf Arvid Rossby was a Swedish-U.S. meteorologist who first explained the large-scale motions of the atmosphere in terms of fluid mechanics....
(who was the first to explain the large scale atmospheric flow in terms of
fluid dynamicsIn physics, fluid dynamics is a sub-discipline of fluid mechanics that deals with fluid flow—the natural science of fluids in motion. It has several subdisciplines itself, including aerodynamics and hydrodynamics...
),
Tor BergeronTor Bergeron was the Swedish meteorologist who proposed a mechanism for the formation of precipitation in clouds. In the 1930s, Bergeron and W. Findeisen developed the concept that clouds contain both supercooled water and ice crystals...
(who first determined the mechanism by which rain forms) and
Jacob BjerknesJacob Aall Bonnevie Bjerknes was a Norwegian-American meteorologist.-Biography:...
.
Observation networks and weather forecasting
In 1654, Ferdinando II de Medici establishes the first
weather observing network, that consisted of meteorological stations in
FlorenceFlorence is the capital city of the Italian region of Tuscany and of the province of Florence...
,
CutiglianoCutigliano is a comune in the province of Pistoia in the Italian region Tuscany, located about 50 km northwest of Florence and about 25 km northwest of Pistoia....
,
VallombrosaVallombrosa is a Benedictine abbey in the comune of Reggello , c. 30 km south-east of Florence, in the Apennines, surrounded by forests of beech and firs. It was founded by Giovanni Gualberto, a Florentine noble, in 1038 and became the mother house of the Vallumbrosan Order.It was extended around...
,
BolognaBologna is the capital city of Emilia-Romagna, in the Po Valley of northern Italy...
,
ParmaParma is a city in the Italian region of Emilia-Romagna famous for its architecture and the fine countryside around it. It is the home of the University of Parma, one of the oldest universities in the world....
,
MilanMilan in Italy, is the capital of the region of Lombardia and of the province of Milan. The city proper has a population of about 1.3 million, while the urban area is the fifth largest in the E.U. with an estimated population of 4.3 million...
,
InnsbruckInnsbruck is the capital city of the federal state of Tyrol in western Austria. It is located in the Inn Valley at the junction with the Wipptal , which provides access to the Brenner Pass, some south of Innsbruck...
,
OsnabruckOsnabrück is a city in Lower Saxony, Germany, some 80 km NNE of Dortmund, 45 km NE of Münster, and some 100 km due west of Hannover. It lies in a valley penned between the Wiehengebirge and the northern tip of the Teutoburg Forest...
,
ParisParis is the capital of France and the country's most populous city. It is situated on the river Seine, in northern France, at the heart of the Île-de-France region...
and
WarsawWarsaw is the capital and largest city of Poland. It is located on the Vistula River roughly from both the Baltic Sea coast and the Carpathian Mountains. Its population as of 2009 was estimated at 1,709,781, and the Warsaw metropolitan area at approximately 2,785,000...
. Collected data was centrally sent to Florence at regular time intervals. In 1832, an electromagnetic telegraph was created by Baron Schilling. The arrival of the
electrical telegraphThe electrical telegraph is a telegraph that uses electric signals. The electromagnetic telegraph is a device for human-to-human transmission of coded text messages over wire...
in 1837 afforded, for the first time, a practical method for quickly gathering
surface weather observationSurface weather observations are the fundamental data used for safety as well as climatological reasons to forecast weather and issue warnings worldwide. They can be taken manually, by a weather observer, by computer through the use of automated weather stations, or in a hybrid scheme using...
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
Smithsonian InstitutionThe Smithsonian Institution is an educational and research institute and associated museum complex, administered and funded by the government of the United States and by funds from its endowment, contributions, and profits from its shops and its magazines...
began to establish an observation network across the
United StatesThe United States of America is a federal constitutional republic comprising fifty states and a federal district...
under the leadership of
Joseph HenryJoseph Henry was an American scientist who served as the first Secretary of the Smithsonian Institution. During his lifetime, he was considered one of the greatest American scientists since Benjamin Franklin. While building electromagnets, Henry discovered the electromagnetic phenomenon of...
. Similar observation networks were established in
EuropeEurope is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally divided from Asia to its east by the water divide of the Ural Mountains, the Ural River, the Caspian Sea, the Caucasus Mountains , and the Black Sea to the southeast...
at this time. In 1854, the
United KingdomThe United Kingdom of Great Britain and Northern Ireland is a sovereign state located off the northwestern coast of continental Europe. It is an island country, spanning an archipelago including Great Britain, the northeastern part of Ireland, and many small islands...
government appointed
Robert FitzRoyVice-Admiral Robert FitzRoy RN achieved lasting fame as the captain of HMS Beagle during Charles Darwin's famous voyage, and as a pioneering meteorologist who made accurate weather forecasting a reality...
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 OfficeThe Met Office , is the United Kingdom's national weather service, and a trading fund of the Ministry of Defence. Part of the Met Office headquarters at Exeter in Devon is the Met Office College, which handles the training for internal personnel and many forecasters from around the world...
in 1854, the first national meteorological service in the world. The first daily weather forecasts made by FitzRoy's Office were published in
The TimesThe Times is a daily national newspaper published in the United Kingdom since 1785 when it was known as The Daily Universal Register....
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
India Meteorological DepartmentThe India Meteorological Department , also referred to as the Met Office, is a Government of India organisation that is responsible for meteorological observations, weather forecasts, and detecting earthquakes. The IMD is also the Regional Specialized Meteorological Center responsible for...
(1875) was established following tropical cyclone and
monsoonA pennis is traditionally defined as a seasonal reversing wind accompanied by seasonal changes in precipitation, but now is used to describe seasonal changes atmospheric circulation and precipitation The major monsoon systems of the world consist of the African and Asia-Australian monsoons...
related
famineA famine is a widespread scarcity of food that may apply to any faunal species, which phenomenon is usually accompanied by regional malnutrition, starvation, epidemic, and increased mortality...
s in the previous decades. The Finnish Meteorological Central Office (1881) was formed from part of Magnetic Observatory of Helsinki University.
Japanis an island country in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, People's Republic of China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
's Tokyo Meteorological Observatory, the forerunner of the
Japan Meteorological AgencyThe or JMA, is the Japanese government's weather service. Charged with gathering and reporting weather data and forecasts in Japan, it is a semi-autonomous part of the Ministry of Land, Infrastructure and Transport...
, began constructing surface weather maps in 1883. The United States Weather Bureau (1890) was established under the
United States Department of AgricultureThe United States Department of Agriculture is the United States federal executive department responsible for developing and executing U.S. federal government policy on farming, agriculture, and food...
. The
Australian Bureau of MeteorologyThe Bureau of Meteorology is an Executive Agency of the Australian Government responsible for providing weather services to Australia and surrounding areas. It was established in 1906 under the Meteorology Act, and brought together the state meteorological services that existed before then...
(1906) was established by a Meteorology Act to unify existing state meteorological services.
Numerical weather prediction
In 1904, Norwegian scientist
Vilhelm BjerknesVilhelm Friman Koren Bjerknes was a Norwegian physicist and meteorologist who did much to found the modern practice of weather forecasting.-Life & career:...
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
natural lawsA physical law or scientific law is a scientific generalization based on empirical observations of physical behavior . Laws of nature are observable. Scientific laws are empirical, describing the observable laws...
.
It was not until later in the 20th century that advances in the understanding of atmospheric physics led to the foundation of modern
numerical weather predictionNumerical weather prediction uses current weather conditions as input into mathematical models of the atmosphere to predict the weather. While the first efforts to accomplish this were done in the 1920s, it wasn't until the advent of the computer that it was feasible to do in real-time...
. In 1922,
Lewis Fry RichardsonLewis Fry Richardson, FRS was an English mathematician, physicist, meteorologist, psychologist and pacifist who pioneered modern mathematical techniques of weather forecasting, and the application of similar techniques to studying the causes of wars and how to prevent them...
published "Weather Prediction By Numerical Process," after finding notes and derivations he worked on as an ambulance driver in World War I. He described therein how small terms in the prognostic fluid dynamics equations governing atmospheric flow could be neglected, and a finite differencing scheme in time and space could be devised, to allow numerical prediction solutions to be found. Richardson envisioned a large auditorium of thousands of people performing the calculations and passing them to others. However, the sheer number of calculations required was too large to be completed without the use of computers, and the size of the grid and time steps led to unrealistic results in deepening systems. It was later found, through numerical analysis, that this was due to numerical instability.
Starting in the 1950s,
numericalA number is a mathematical object used in counting and measuring. A notational symbol which represents a number is called a numeral, but in common usage the word number is used for both the abstract object and the symbol, as well as for the word for the number...
forecasts with computers became feasible. The first weather forecasts derived this way used
barotropicIn meteorology, a barotropic atmosphere is one in which the pressure depends only on the density and vice versa, so that isobaric surfaces are also isopycnic surfaces . The isobaric surfaces will also be isothermal surfaces, hence the geostrophic wind is independent of height...
(that means, single-vertical-level) models, and could successfully predict the large-scale movement of midlatitude
Rossby waveRossby waves are giant meanders in high-altitude winds that are a major influence on weather. Their emergence is due to shear in rotating fluids, so that the Coriolis force changes along the sheared coordinate. In planetary atmospheres, they are due to the variation in the Coriolis effect with...
s, that is, the pattern of
atmospheric lowsA low pressure area, or "low", is a region where the atmospheric pressure is lower in relation to the surrounding area. Low pressure systems form under areas of upper level divergence on the east side of upper troughs, or due to localized heating caused by greater insolation or active thunderstorm...
and
highsA high-pressure area is a region where the atmospheric pressure at the surface of the planet is greater than its surrounding environment. Winds within high-pressure areas flow outward due to the higher density air near their center and friction with land...
.
In the 1960s, the
chaoticChaos typically refers to a state lacking order or predictability. In ancient Greece, it referred to the initial state of the universe, and, by extension, space, darkness, or an abyss...
nature of the atmosphere was first observed and understood by Edward Lorenz, founding the field of
chaos theoryChaos theory is a branch of mathematics which studies the behavior of certain dynamical systems that may be highly sensitive to initial conditions. This sensitivity is popularly referred to as the butterfly effect. As a result of this sensitivity, which manifests itself as an exponential growth of...
. These advances have led to the current use of
ensemble forecastingEnsemble forecasting is a numerical prediction method that is used to attempt to generate a representative sample of the possible future states of a dynamical system...
in most major forecasting centers, to take into account uncertainty arising from the chaotic nature of the atmosphere. In recent years,
climate modelClimate models use quantitative methods to simulate the interactions of the atmosphere, oceans, land surface, and ice. They are used for a variety of purposes from study of the dynamics of the climate system to projections of future climate....
s have been developed that feature a resolution comparable to older weather prediction models. These climate models are used to investigate long-term
climateClimate encompasses the statistics of temperature, humidity, atmospheric pressure, wind, rainfall, atmospheric particle count and numerous other meteorological elements in a given region over long periods of time...
shifts, such as what effects might be caused by human emission of
greenhouse gasGreenhouse gases are gases in an atmosphere that absorb and emit radiation within the thermal infrared range. This process is the fundamental cause of the greenhouse effect. The main greenhouse gases in the Earth's atmosphere are water vapor, carbon dioxide, methane, nitrous oxide, and ozone...
es.
Meteorologists
Meteorologists are
scientistA scientist, in the broadest sense, is any person who engages in a systematic activity to acquire knowledge or an individual that engages in such practices and traditions that are linked to schools of thought or philosophy. In a more restricted sense, a scientist is an individual who uses the...
s who study meteorology. Meteorologists work in government agencies, private consulting and
researchResearch can be defined to be search for knowledge or any systematic investigation to establish facts. The primary purpose for applied research is discovering, interpreting, and the development of methods and systems for the advancement of human knowledge on a wide variety of scientific matters of...
services, industrial enterprises, utilities, radio and television stations, and in
educationEducation in its broadest sense is any act or experience that has a formative effect on the mind, character or physical ability of an individual...
. In the United States, meteorologists held about 8,800 jobs in 2006.
Meteorologists are best-known for forecasting the
weatherWeather is a set of all the phenomena occurring in a given atmosphere at a given time. Weather phenomena lie in the troposphere. Weather refers, generally, to day-to-day temperature and precipitation activity, whereas climate is the term for the average atmospheric conditions over longer periods...
. In 2006, more than 90 percent of the around 3,200 meteorologists employed by the
National Oceanic and Atmospheric AdministrationThe National Oceanic and Atmospheric Administration is a scientific agency within the United States Department of Commerce focused on the conditions of the oceans and the atmosphere...
worked as forecasters in the
National Weather ServiceThe National Weather Service , once known as the Weather Bureau, is one of the six scientific agencies that make up the National Oceanic and Atmospheric Administration of the United States government...
. Many radio and television weather forecasters are professional meteorologists, while others are merely reporters with no formal meteorological training. The
American Meteorological SocietyThe American Meteorological Society promotes the development and dissemination of information and education on the atmospheric and related oceanic and hydrologic sciences and the advancement of their professional applications. Founded in 1919, the American Meteorological Society has a membership...
and
National Weather AssociationThe National Weather Association is an American scientific organization with a mission to support and promote excellence in operational meteorology and related activities...
issue "Seals of Approval" to weather broadcasters who meet certain requirements.
Equipment
Each 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 ones to be 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
rain gaugeA rain gauge is a type of instrument used by meteorologists and hydrologists to gather and measure the amount of liquid precipitation over a set period of time.-History:The first known records of rainfalls were kept by the...
, the anemometer, and the hygrometer.
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
weather stationA weather station is a facility with instruments and equipment for observing atmospheric conditions to provide information for weather forecasts and to study the weather and climate. The measurements taken include temperature, barometric pressure, humidity, wind speed, wind direction, and...
, a
shipA ship is a large vessel that floats on water. Ships are generally distinguished from boats based on size and passenger capacity. Ships may be found on lakes, seas, and rivers and they allow for a variety of activities, such as the transport of people or goods, fishing, entertainment, public...
or a
weather buoyWeather buoys are instruments which collect weather and ocean data within the world's oceans. They measure parameters such as air temperature at the ocean surface, water temperature, wave height, dominant wave period, barometric pressure, wind speed , and wind direction...
. The measurements taken at a weather station can include any number of atmospheric observables. Usually, temperature,
pressureAtmospheric pressure is defined as the force per unit area exerted against a surface by the weight of air above that surface at any given point in the Earth's atmosphere. In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above...
, wind measurements, and
humidityHumidity is the amount of water vapour in the air. In daily language the term "humidity" is normally taken to mean relative humidity. Relative humidity is defined as the ratio of the partial pressure of water vapour in a parcel of air to the saturated vapour pressure of water vapour at a prescribed...
are the variables that are measured by a thermometer, barometer, anemometer, and hygrometer, respectively. Upper air data are of crucial importance for weather forecasting. The most widely used technique is launches of radiosondes. Supplementing the radiosondes a network of aircraft collection is organized by the
World Meteorological OrganizationThe World Meteorological Organization is an intergovernmental organization with a membership of 188 Member States and Territories. It originated from the International Meteorological Organization , which was founded in 1873...
.
Remote sensingRemote sensing is the small or large-scale acquisition of information of an object or phenomenon, by the use of either recording or real-time sensing device that are wireless, or not in physical or intimate contact with the object...
, 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
RadarRadar is an object detection system that uses electromagnetic waves to identify the range, altitude, direction, or speed of both moving and fixed objects such as aircraft, ships, motor vehicles, weather formations, and terrain. The term RADAR was coined in 1941 as an acronym for RAdio Detection And...
,
LidarLIDAR is an optical remote sensing technology that measures properties of scattered light to find range and/or other information of a distant target. The prevalent method to determine distance to an object or surface is to use laser pulses...
, and satellites (or
photogrammetryPhotogrammetry is the first remote sensing technology ever developed in which geometric properties about objects are determined from photographic images...
). 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 EM radiation 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 El Niño.
Spatial scales
In the study of the atmosphere, meteorology can be divided into distinct areas of emphasis depending on the temporal scope and spatial scope of interest. 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
geospatialGeospatial is a term widely used to describe the combination of spatial software and analytical methods with terrestrial or geographic datasets. The term is often used in conjunction with geographic information systems and geomatics, never separately...
size of each of these three scales relates directly with the appropriate timescale.
Other subclassifications are available based on the need by or by the unique, local or broad effects that are studied within that sub-class.
Microscale
Microscale meteorology is the study of atmospheric phenomena of about 1 km or less. Individual thunderstorms, clouds, and local turbulence caused by buildings and other obstacles, such as individual hills fall within this category.
Mesoscale
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,
tropopauseThe tropopause is the atmospheric boundary between the troposphere and the stratosphere. Going upward from the surface, it is the point where air ceases to cool with height, and becomes almost completely dry. More formally, it is the region of the atmosphere where the lapse rate changes from...
, and the lower section of the
stratosphereThe stratosphere is the second major layer of Earth's atmosphere, just above the troposphere, and below the mesosphere. It is stratified in temperature, with warmer layers higher up and cooler layers farther down. This is in contrast to the troposphere near the Earth's surface, which is cooler...
. 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
thunderstormA thunderstorm, also known as an electrical storm, a lightning storm, a hailstorm, or simply a storm is a form of weather characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere known as thunder. The meteorologically-assigned cloud type associated with the...
s,
squall lineA squall line is a line of severe thunderstorms that can form along and/or ahead of a cold front. In the early 20th century, the term was used as a synonym for cold front. It contains heavy precipitation, hail, frequent lightning, strong straight line winds, and possibly tornadoes and waterspouts...
s,
fronts--173.70.199.81 20:00, 14 October 2009 --173.70.199.81 20:00, 14 October 2009 --173.70.199.81 20:00, 14 October 2009...
, precipitation bands in
tropicalA tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones feed on heat released when moist air rises, resulting in condensation of water vapor contained in the moist air...
and
extratropical cycloneExtratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are a group of cyclones defined as synoptic scale low pressure weather systems that occur in the middle latitudes of the Earth having neither tropical nor polar characteristics, and are connected with fronts and...
s, and topographically generated weather systems such as mountain waves and
sea and land breezesA sea-breeze is a wind from the sea that develops over land near coasts. It is formed by increasing temperature differences between the land and water which create a pressure minimum over the land due to its relative warmth and forces higher pressure, cooler air from the sea to move inland...
.
Synoptic scale
Synoptic scale meteorology 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--173.70.199.81 20:00, 14 October 2009 --173.70.199.81 20:00, 14 October 2009 --173.70.199.81 20:00, 14 October 2009...
, and to some extent
jet streamJet streams are fast flowing, narrow air currents found in the atmosphere of planets at the tropopause, the transition between the troposphere and the stratosphere . The major jet streams on earth are westerly winds...
s. All of these are typically given on
weather mapA weather map is a tool used to display information quickly, showing the analysis of various meteorological quantities at various levels of the atmosphere. Maps using isotherms show temperature gradients, which can help locate weather fronts. Isotach maps, analyzing lines of equal wind speed, on...
s for a specific time. The minimum horizontal scale of synoptic phenomena are limited to the spacing between
surface observation stationsA weather station is a facility with instruments and equipment for observing atmospheric conditions to provide information for weather forecasts and to study the weather and climate. The measurements taken include temperature, barometric pressure, humidity, wind speed, wind direction, and...
.
Global scale
Global scale meteorology is study of weather patterns related to the transport of heat from the
tropicsThe tropics,the tropics are very hot. hi everyone! peace out!seated in the equatorial regions of the world, are limited in latitude by the Tropic of Cancer in the northern hemisphere at approximately 23°26' N latitude and the Tropic of Capricorn in the southern hemisphere at 23°26' S latitude...
to the
polesA geographical pole is either of the two points—the north pole and the south pole—on the surface of a rotating planet where the axis of rotation meets the surface of the body...
. Also, very large scale oscillations are of importance. Those oscillations have time periods typically longer than a full annual seasonal cycle, such as
ENSOEnsō is a Japanese word meaning "circle" and a concept strongly associated with Zen. Ensō is one of the most common subjects of Japanese calligraphy even though it is a symbol and not a character. It symbolizes enlightenment, strength, elegance, the Universe, and the void; it can also symbolize...
,
PDOThe Pacific decadal oscillation is a pattern of Pacific climate variability that shifts phases on at least inter-decadal time scale, usually about 20 to 30 years. The PDO is detected as warm or cool surface waters in the Pacific Ocean, north of 20° N...
, 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.. Currently (2007) Naval Research Laboratory in Monterey produces the atmospheric model called
NOGAPS, a global scale atmospheric model, this model is run operationally at Fleet Numerical Meteorology and Oceanography Center. There are several other global atmospheric models.
Boundary layer meteorology
Boundary layerIn physics and fluid mechanics, a boundary layer is that layer of fluid in the immediate vicinity of a bounding surface. In the Earth's atmosphere, the planetary boundary layer is the air layer near the ground affected by diurnal heat, moisture or momentum transfer to or from the surface. On an...
meteorology is the study of processes in the air layer directly above Earth's surface, known as the
atmospheric boundary layerThe planetary boundary layer , also known as the atmospheric boundary layer , is the lowest part of the atmosphere and its behavior is directly influenced by its contact with a planetary surface. On Earth it usually responds to changes in surface forcing in an hour or less...
(ABL). The effects of the surface – heating, cooling, and
frictionFriction is the force resisting the relative lateral motion of solid surfaces, fluid layers, or material elements in contact. It is usually subdivided into several varieties:...
– cause
turbulent mixingIn fluid dynamics, turbulence or turbulent flow is a fluid regime characterized by chaotic, stochastic property changes. This includes low momentum diffusion, high momentum convection, and rapid variation of pressure and velocity in space and time. Flow that is not turbulent is called laminar flow...
within the air layer. Significant
fluxIn the various subfields of physics, there exist two common usages of the term flux, both with rigorous mathematical frameworks.* In the study of transport phenomena , flux is defined as the amount that flows through a unit area per unit time...
es of
heatSensible heat is potential energy in the form of thermal energy, or heat, and refers to the heat that is added or removed from the air and dry bulb temperature changes without water vapor content change. The thermal body must have a temperature higher than its surroundings...
,
matterThe term matter traditionally refers to the substance that all objects are made of. One common way to identify this "substance" is through its physical properties; a common definition of matter is anything that has mass and occupies a volume...
, or
momentumIn classical mechanics, momentum is the product of the mass and velocity of an object . For more accurate measures of momentum, see the section "modern definitions of momentum" on this page...
on time scales of less than a day are advected 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.
Dynamic meteorology
Dynamic meteorology generally focuses on the
fluid dynamicsIn physics, fluid dynamics is a sub-discipline of fluid mechanics that deals with fluid flow—the natural science of fluids in motion. It has several subdisciplines itself, including aerodynamics and hydrodynamics...
of the atmosphere. The idea of
air parcelIn fluid dynamics, within the framework of continuum mechanics, a fluid parcel is a very small amount of fluid, identifiable throughout its dynamic history while moving with the fluid flow. As it moves, the mass of a fluid parcel remains constant, while—in a compressible flow—its volume may...
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 forecasting
Weather forecasting is the application of science and technology to predict the state of the
atmosphereThe Earth's atmosphere is a layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention , and reducing temperature extremes between day and night...
for a future time and a given location. Human beings have attempted to predict the weather informally for millennia, and formally since at least the nineteenth century. Weather forecasts are made by collecting quantitative
dataThe term data means groups of information that represent the qualitative or quantitative attributes of a variable or set of variables. Data are typically the results of measurements and can be the basis of graphs, images, or observations of a set of variables...
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
barometric pressureAtmospheric pressure is defined as the force per unit area exerted against a surface by the weight of air above that surface at any given point in the Earth's atmosphere. In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above...
, current weather conditions, and sky condition,
forecast modelsNumerical weather prediction uses current weather conditions as input into mathematical models of the atmosphere to predict the weather. While the first efforts to accomplish this were done in the 1920s, it wasn't until the advent of the computer that it was feasible to do in real-time...
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,
teleconnectionTeleconnection in atmospheric science refers to climate anomalies being related to each other at large distances...
s, knowledge of model performance, and knowledge of model biases. The
chaoticChaos theory is a branch of mathematics which studies the behavior of certain dynamical systems that may be highly sensitive to initial conditions. This sensitivity is popularly referred to as the butterfly effect. As a result of this sensitivity, which manifests itself as an exponential growth of...
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 users to weather forecasts. Weather warnings are important forecasts because they are used to protect life and property. Forecasts based on temperature and
precipitationIn meteorology, precipitation is any product of the condensation of atmospheric water vapor that is deposited on the Earth's surface. The main forms of precipitation include rain, snow, ice pellets, and graupel...
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 on a given day. Since outdoor activities are severely curtailed by heavy rain,
snowSnow is a type of precipitation in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds. Since snow is composed of small ice particles, it is a granular material. It has an open and therefore soft structure, unless packed by external pressure. Snowflakes...
and the
wind chillWind chill is the apparent temperature felt on exposed skin due to wind. The degree of this phenomenon depends on both air temperature and wind speed. The wind chill temperature is always lower than the air temperature for values where the wind chill formula is valid...
, forecasts can be used to plan activities around these events, and to plan ahead and survive them.
Aviation meteorology
Aviation meteorology deals with the impact of weather on
air traffic managementAir traffic control is a service provided by ground-based controllers who direct aircraft on the ground and in the air. The primary purpose of ATC systems worldwide is to separate aircraft to prevent collisions, to organize and expedite the flow of traffic, and to provide information and other...
. 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 ManualIn United States aviation, the Aeronautical Information Manual is the Federal Aviation Administration's official guide to basic flight information and ATC procedures....
:
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 meteorology
Meteorologists,
soil scientistsSoil science is the study of soil as a natural resource on the surface of the earth including soil formation, classification and mapping; physical, chemical, biological, and fertility properties of soils; and these properties in relation to the use and management of soils.Sometimes terms which...
, agricultural hydrologists, and
agronomistsAgronomy is the science and technology of using plants for food, fuel, feed, and fiber. Agronomy encompasses work in the areas of plant genetics, plant physiology, meteorology, and soil science. Agronomy is the application of a combination of sciences like biology, chemistry, ecology, earth...
are persons concerned with studying the effects of weather and climate on plant distribution,
crop yieldIn agriculture, crop yield is not only a measure of the yield of cereal per unit area of land under cultivation, it is also the seed generation of the plant itself, i.e. one grain of wheat produces a stalk yielding three grain, or 1:3...
, water-use efficiency,
phenologyPhenology is the study of periodic plant and animal life cycle events and how these are influenced by seasonal and interannual variations in climate. The word is derived from the Greek phainomai and indicates that phenology has been principally concerned with the dates of first occurrence of...
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.
Hydrometeorology
HydrometeorologyHydrometeorology is a branch of meteorology and hydrology that studies the transfer of water and energy between the land surface and the lower atmosphere....
is the branch of meteorology that deals with the hydrologic cycle, the water budget, and the rainfall statistics of
stormA storm is any disturbed state of an astronomical body's atmosphere, especially affecting its surface, and strongly implying severe weather...
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.
Nuclear meteorology
NuclearNuclear may refer to:*Atomic nucleus**Nuclear physics**Nuclear power**Nuclear weapon*Cell nucleus**Nuclear DNA-See also:*Nucleus *Nucleolus*Nucleation*Nucleic acid*Nuclear family...
meteorology investigates the distribution of radioactive
aerosolTechnically, an aerosol is a suspension of fine solid particles or liquid droplets in a gas. Examples are smoke, oceanic haze, air pollution, smog and CS gas. In general conversation, aerosol usually refers to an aerosol spray can or the output of such a can...
s and
gasThis page is about the physical properties of gas as a state of matter. For the uses of gases, and other meanings, see Gas .A gas is one of four states of matter. Near absolute zero, a substance exists as a solid...
es in the atmosphere.
Maritime meteorology
Maritime meteorology deals with air and wave forecasts for ships operating at sea. Organizations such as the
Ocean Prediction CenterThe Ocean Prediction Center , established in 1995, is one of the National Centers for Environmental Prediction’s original six service centers. Until January 12, 2003, the name of the organization was the Marine Prediction Center. Its origins are traced back to the sinking of the Titanic in 1912...
, Honolulu
National Weather ServiceThe National Weather Service , once known as the Weather Bureau, is one of the six scientific agencies that make up the National Oceanic and Atmospheric Administration of the United States government...
forecast office,
United KingdomThe United Kingdom of Great Britain and Northern Ireland is a sovereign state located off the northwestern coast of continental Europe. It is an island country, spanning an archipelago including Great Britain, the northeastern part of Ireland, and many small islands...
Met OfficeThe Met Office , is the United Kingdom's national weather service, and a trading fund of the Ministry of Defence. Part of the Met Office headquarters at Exeter in Devon is the Met Office College, which handles the training for internal personnel and many forecasters from around the world...
, and JMA prepare high seas forecasts for the world's oceans.
See also
- American Practical Navigator
- Atmospheric circulation
Atmospheric circulation is the large-scale movement of air, and the means by which thermal energy is distributed on the surface of the Earth....
- Atmospheric dynamics
- Atmospheric layers
- Atmospheric models
Static atmospheric models describe how the ideal gas properties of an atmosphere change, primarily as a function of altitude....
- Atmospheric thermodynamics
In the physical sciences, atmospheric thermodynamics is the study of heat and energy transformations in the earth’s atmospheric system. Following the fundamental laws of classical thermodynamics, atmospheric thermodynamics studies such phenomena as properties of moist air, formation of clouds,...
- ENSO
Ensō is a Japanese word meaning "circle" and a concept strongly associated with Zen. Ensō is one of the most common subjects of Japanese calligraphy even though it is a symbol and not a character. It symbolizes enlightenment, strength, elegance, the Universe, and the void; it can also symbolize...
(El Niño-Southern Oscillation)
- Index of meteorology articles
- List of weather instruments
- List of meteorology institutions
- Madden-Julian oscillation
The Madden–Julian oscillation ' is an equatorial traveling pattern of anomalous rainfall that is planetary in scale. The mechanism and cause of the MJO is as yet not well-understood and is a subject of ongoing study....
- Meteorological Winter
Meteorological winter is a method of measuring the season of winter used by meteorologists based on "sensible weather patterns" for record keeping purposes, i.e. whenever snow and or freezing precipitation occurs, unlike astronomical winter which is based solely on the position of the Earth in its...
- Space weather
Space weather is the concept of changing environmental conditions in near-Earth space. It is distinct from the concept of weather within a planetary atmosphere, and deals with phenomena involving ambient plasma, magnetic fields, radiation and other matter in space...
- Walker circulation
The Walker circulation, also known as the Walker cell, is a conceptual model of the air flow in the tropics in the lower atmosphere . According to this model parcels of air follow a closed circulation in the zonal and vertical directions...
External links
Please see weather forecastingWeather forecasting is the application of science and technology to predict the state of the atmosphere for a future time and a given location. Human beings have attempted to predict the weather informally for millennia, and formally since at least the nineteenth century...
for weather forecast sites.
| Links to other keywords in meteorology |
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Atmospheric conditions: Absolute stable air > Temperature inversion | Dine's compensationIn meteorology, Dine's compensation states that net mass convergence into a given column of air must be balanced by a net mass divergence from the same column of air. The implication is that rising air in the atmosphere must be balanced by equal sinking or subsiding air.Dines compensation applies...
| precipitationIn meteorology, precipitation is any product of the condensation of atmospheric water vapor that is deposited on the Earth's surface. The main forms of precipitation include rain, snow, ice pellets, and graupel...
| CycloneIn meteorology, a cyclone is an area of closed, circular fluid motion rotating in the same direction as the Earth. This is usually characterized by inward spiraling winds that rotate counter clockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere of the Earth.Large-scale...
| anticycloneIn meteorology, an anticyclone is a weather phenomenon in which there is a descending movement of the air, and with surface systems, higher than average atmospheric pressure over the part of the planet's surface. Effects of surface-based anticyclones include clearing skies as well as cooler,...
| ThermalA thermal column is a column of rising air in the lower altitudes of the Earth's atmosphere. Thermals are created by the uneven heating of the Earth's surface from solar radiation, and an example of convection. The Sun warms the ground, which in turn warms the air directly above it....
| Tropical cycloneA tropical cyclone is a storm system characterized by a large low-pressure center and numerous thunderstorms that produce strong winds and heavy rain. Tropical cyclones feed on heat released when moist air rises, resulting in condensation of water vapor contained in the moist air...
(hurricane or typhoon) | Vertical draftAn updraft or downdraft is the vertical movement of air as a weather related phenomenon. Commonly, one of two forces causes the air to move. Localized regions of warm or cool air will exhibit vertical movement...
| Extratropical cycloneExtratropical cyclones, sometimes called mid-latitude cyclones or wave cyclones, are a group of cyclones defined as synoptic scale low pressure weather systems that occur in the middle latitudes of the Earth having neither tropical nor polar characteristics, and are connected with fronts and...
Weather forecastingWeather forecasting is the application of science and technology to predict the state of the atmosphere for a future time and a given location. Human beings have attempted to predict the weather informally for millennia, and formally since at least the nineteenth century...
: atmospheric pressureAtmospheric pressure is defined as the force per unit area exerted against a surface by the weight of air above that surface at any given point in the Earth's atmosphere. In most circumstances atmospheric pressure is closely approximated by the hydrostatic pressure caused by the weight of air above...
| Low pressure areaA low pressure area, or "low", is a region where the atmospheric pressure is lower in relation to the surrounding area. Low pressure systems form under areas of upper level divergence on the east side of upper troughs, or due to localized heating caused by greater insolation or active thunderstorm...
| High pressure areaA high-pressure area is a region where the atmospheric pressure at the surface of the planet is greater than its surrounding environment. Winds within high-pressure areas flow outward due to the higher density air near their center and friction with land...
| dew pointThe dew point is the temperature to which a given parcel of air must be cooled, at constant barometric pressure, for water vapor to condense into water. The condensed water is called dew. The dew point is a saturation point...
| weather front--173.70.199.81 20:00, 14 October 2009 --173.70.199.81 20:00, 14 October 2009 --173.70.199.81 20:00, 14 October 2009...
| jet streamJet streams are fast flowing, narrow air currents found in the atmosphere of planets at the tropopause, the transition between the troposphere and the stratosphere . The major jet streams on earth are westerly winds...
| windchill | heat indexThe heat index is an index that combines air temperature and relative humidity in an attempt to determine the human-perceived equivalent temperature — how hot it feels, termed the felt air temperature. The human body normally cools itself by perspiration, or sweating, which evaporates and carries...
| Theta-eEquivalent potential temperature, commonly referred to as Theta-e , is a quantity related to the stability of a column of air in the atmosphere....
| primitive equationsThe primitive equations are a set of nonlinear differential equations that are used to approximate global atmospheric flow and are used in most atmospheric models...
| Pilot ReportsA pilot report or PIREP is a report of actual weather conditions encountered by an aircraft in flight. This information is usually relayed by radio to the nearest ground station...
StormA storm is any disturbed state of an astronomical body's atmosphere, especially affecting its surface, and strongly implying severe weather...
: thunderstormA thunderstorm, also known as an electrical storm, a lightning storm, a hailstorm, or simply a storm is a form of weather characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere known as thunder. The meteorologically-assigned cloud type associated with the...
| lightningLightning is an atmospheric discharge of electricity accompanied by thunder, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms...
| thunderThunder is the sound made by lightning. Depending on the nature of the lightning and distance of the listener, it can range from a sharp, loud crack to a long, low rumble . The sudden increase in pressure and temperature from lightning produces rapid expansion of the air surrounding and within a...
| hailHail is a form of solid precipitation which consists of balls or irregular lumps of ice, that are individually called hail stones. Hail stones on Earth consist mostly of water ice and measure between 5 and 150 millimeters in diameter, with the larger stones coming from severe and dangerous...
| tornadoA tornado is a violent, dangerous, rotating column of air which is in contact with both the surface of the earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud...
| convectionConvection is the movement of molecules within fluids . Convection is one of the major modes of heat transfer and mass transfer...
| blizzardA blizzard is a severe winter storm condition characterized by low temperatures, strong winds, and heavy blowing snow...
| supercellA supercell is a thunderstorm that is characterized by the presence of a mesocyclone; a deep, continuously-rotating updraft. Of the four classifications of thunderstorms , supercells are the overall least common and have the potential to be the most severe...
ClimateClimate encompasses the statistics of temperature, humidity, atmospheric pressure, wind, rainfall, atmospheric particle count and numerous other meteorological elements in a given region over long periods of time...
: El Niño | monsoonA pennis is traditionally defined as a seasonal reversing wind accompanied by seasonal changes in precipitation, but now is used to describe seasonal changes atmospheric circulation and precipitation The major monsoon systems of the world consist of the African and Asia-Australian monsoons...
| floodA flood is an overflow or accumulation of an expanse of water that submerges land. In the sense of "flowing water", the word may also be applied to the inflow of the tide....
| droughtA drought is an extended period of months or years when a region notes a deficiency in its water supply. Generally, this occurs when a region receives consistently below average precipitation. It can have a substantial impact on the ecosystem and agriculture of the affected region...
| Global warmingGlobal warming is the increase in the average temperature of the Earth's near-surface air and oceans since the mid-20th century and its projected continuation. Global surface temperature increased 0.74 ± 0.18 °C during the last century...
| Effect of sun angle on climateThe amount of heat energy received at any location on the globe is a direct effect of sun angle of climate, as the angle at which sunlight strikes the Earth varies by location, time of day, and season due to the Earth's orbit around the sun and the Earth's revolution around its tilted axis...
.
Air PollutionAir pollution is the introduction of chemicals, particulate matter, or biological materials that cause harm or discomfort to humans or other living organisms, or damages the natural environment, into the atmosphere....
: Air pollution dispersion modelingAtmospheric dispersion modeling is the mathematical simulation of how air pollutants disperse in the ambient atmosphere. It is performed with computer programs that solve the mathematical equations and algorithms which simulate the pollutant dispersion...
| List of atmospheric dispersion models | SmogSmog is a kind of air pollution; the word "smog" is a portmanteau of smoke and fog. Classic smog results from large amounts of coal burning in an area caused by a mixture of smoke and sulfur dioxide...
Other phenomena: deposition | dust devilA dust devil is a strong, well-formed, and relatively long-lived whirlwind, ranging from small to large . The primary vertical motion is upward...
| fogFog is a cloud that is in contact with the ground. A cloud may be considered partly fog; for example, the part of a cloud that is suspended in the air above the ground is not considered fog, whereas the part of the cloud that comes in contact with higher ground is considered fog...
| tideTides are the rises and falls of sea level caused by the combined effect of rotation of the Earth and the gravitation of the Moon and the Sun. The tides occur with a period of approximately 12 and a half hours and are influenced by the shape of the near-shore bottom.Most coastal areas experience...
| windWind is the flow of air or other gases that compose an atmosphere . On Earth, wind consists of the bulk movement of air...
| cloudA cloud is a visible mass of droplets or frozen crystals suspended in the atmosphere above the surface of the Earth or another planetary body. A cloud is also a visible mass attracted by gravity, such as masses of material in space called interstellar clouds and nebulae...
| air massIn meteorology, an air mass is a large volume of air defined by its temperature and water vapor content. Air masses cover many hundreds or thousands of square miles, and adopt the characteristics of the surface below them. They are classified according to latitude and their continental or...
| evaporationEvaporation is the vaporization of a liquid and the reverse, of condensation. A type of phase transition, it is the process by which molecules in a liquid state spontaneously become gaseous . Generally, evaporation can be seen by the gradual disappearance of a liquid from a substance when exposed...
| sublimation | iceIce is a solid phase, usually crystalline, of a non-metallic substance that is liquid or gas at room temperature, such as carbon dioxide ice , ammonia ice, or methane ice. However, the predominant use of the term ice is for water ice, technically restricted to one of the 15 known crystalline phases...
| crepuscular raysCrepuscular rays, in atmospheric optics are rays of sunlight that appear to radiate from a single point in the sky. These rays, which stream through gaps in clouds or between other objects, are columns of sunlit air separated by darker cloud-shadowed regions...
| anticrepuscular raysAnticrepuscular rays are similar to crepuscular rays, but seen opposite the sun in the sky. Sunlight travels in straight lines, but the projections of these lines on Earth's spherical atmosphere are great circles. Hence, straight-line crepuscular rays from a setting sun can appear to re-converge...
Weather-related disasters: weather disastersWeather disasters are natural disasters caused by rain, drought, snow, extreme heat or cold, ice, or wind.Examples of weather disasters include blizzards, cyclonic storms, droughts, hailstorms, heatwaves, and tornadoes.- External links :* * *...
| extreme weather]Extreme weather includes weather phenomena that are at the extremes of the historical distribution, especially severe or unseasonal weather.-Related to significant tropical cyclones:...
Climatic or Atmospheric Patterns: Alberta clipperAn Alberta clipper is a fast moving low pressure area which generally affects the central provinces of Canada and parts of the Upper Midwest and Great Lakes regions of the United States. Most clippers occur between December and February, but can also occur occasionally in the month of November...
| El Niño | DerechoA derecho is a widespread and long-lived, violent convectively induced straight-line windstorm that is associated with a fast-moving band of severe thunderstorms in the form of a squall line usually taking the form of a bow echo...
| Gulf StreamThe Gulf Stream, together with its northern extension towards Europe, the North Atlantic Drift, is a powerful, warm, and swift Atlantic ocean current that originates in the Gulf of Mexico, exits through the Strait of Florida, and follows the eastern coastlines of the United States and Newfoundland...
| La NiñaLa Niña is a coupled ocean-atmosphere phenomenon similar to El Niño. During a period of La Niña, the sea surface temperature across the equatorial Eastern Central Pacific Ocean will be lower than normal by 0.5 °C. In the United States, an episode of La Niña is defined as a period of at least 5...
| Jet streamJet streams are fast flowing, narrow air currents found in the atmosphere of planets at the tropopause, the transition between the troposphere and the stratosphere . The major jet streams on earth are westerly winds...
| North Atlantic OscillationThe North Atlantic oscillation is a climatic phenomenon in the North Atlantic Ocean of fluctuations in the difference of atmospheric pressure at sea-level between the Icelandic Low and the Azores high. Through east-west oscillation motions of the Icelandic Low and the Azores high, it controls the...
| Madden-Julian oscillationThe Madden–Julian oscillation ' is an equatorial traveling pattern of anomalous rainfall that is planetary in scale. The mechanism and cause of the MJO is as yet not well-understood and is a subject of ongoing study....
| Pacific decadal oscillationThe Pacific decadal oscillation is a pattern of Pacific climate variability that shifts phases on at least inter-decadal time scale, usually about 20 to 30 years. The PDO is detected as warm or cool surface waters in the Pacific Ocean, north of 20° N...
| Pineapple ExpressPineapple Express is a non-technical, shorthand term popular in the news media for a meteorological phenomenon which is characterized by a strong and persistent flow of atmospheric moisture and associated heavy rainfall from the waters adjacent to the Hawaiian Islands and extending to any location...
| SiroccoSirocco, scirocco, jugo or, rarely, siroc is a Mediterranean wind that comes from the Sahara and reaches hurricane speeds in North Africa and Southern Europe. It is known in North Africa by the Arabic word qibli or ghibli Sirocco, scirocco, jugo or, rarely, siroc is a Mediterranean wind that comes...
| Siberian ExpressSiberian Express is a shorthand meteorological term in the United States describing the arrival of an extremely cold air mass of Arctic origins. It does not necessarily refer to an origin in Siberia...
| Walker circulationThe Walker circulation, also known as the Walker cell, is a conceptual model of the air flow in the tropics in the lower atmosphere . According to this model parcels of air follow a closed circulation in the zonal and vertical directions...