The weather is a set of all the phenomena in a given atmosphere at a given time. A phenomenon (from Greek φαινόμενoν, pl φαινόμενα - phenomena) is any observable occurrence An atmosphere (from Greek ατμός - atmos, " Vapor " + σφαίρα - sphaira, " Sphere " For other uses see Time (disambiguation Time is a component of a measuring system used to sequence events to compare the durations of It also includes interactions with the hydrosphere. The term usually refers to the activity of these phenomena over short periods (hours or days), as opposed to the term climate, which refers to the average atmospheric conditions over longer periods of time. Climate encompasses the temperatures humidity rainfall atmospheric particle count and numerous other meteorogical factors in a given region over long periods of When used without qualification, "weather" is understood to be the weather of Earth. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001

Weather most often results from temperature differences from one place to another. On large scales, temperature differences occur because areas closer to the equator receive more energy per unit area from the Sun than do regions closer to the poles. The equator (sometimes referred to colloquially as "the Line") is the intersection of the Earth 's surface with the plane perpendicular to the The Sun (Sol is the Star at the center of the Solar System. Earth's polar regions are the areas of the globe surrounding the poles also known as frigid zones. On local scales, temperature differences can occur because different surfaces (such as oceans, forests, ice sheets, or man-made objects) have differing physical characteristics such as reflectivity, roughness, or moisture content. An ocean (from Greek, ''Okeanos'' (Oceanus) is a major body of saline water, and a principal component of the Hydrosphere. A forest is an area with a high density of Trees There are many definitions of a forest based on various criteria Ice is a Solid phase, usually crystalline, of a Non-metalic substance that is liquid or gas at Room temperature, such as Ammonia The albedo of an object is the extent to which it diffusely reflects light from the sun

Surface temperature differences in turn cause pressure differences. Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature A hot surface heats the air above it and the air expands, lowering the air pressure. The resulting horizontal pressure gradient accelerates the air from high to low pressure, creating wind, and Earth's rotation then causes curvature of the flow via the Coriolis effect. In atmospheric sciences ( Meteorology, Climatology and related fields the pressure gradient (typically of air, more generally of any Fluid) Wind is the flow of Air or other Gases that compose an Atmosphere (including but not limited to the Earth's) In physics the Coriolis effect is an apparent deflection of moving objects when they are viewed from a Rotating frame of reference. The simple systems thus formed can then display emergent behaviour to produce more complex systems and thus other weather phenomena. For other uses see Emergence (disambiguation, Emergent, and Emergency. A pressure system is a region of the Earth's atmosphere where air pressure is unusually high or low Large scale examples include the Hadley cell while a smaller scale example would be coastal breezes. The Hadley cell is a circulation pattern that dominates the tropical atmosphere with rising motion near the equator poleward flow 10-15 kilometers above the surface descending motion A sea-breeze (or onshore breeze) is a Wind from the sea that develops over land near coasts

The strong temperature contrast between polar and tropical air gives rise to the jet stream. Jet streams are fast flowing relatively narrow air currents found at the Tropopause, the transition between the Troposphere (where temperature decreases Most weather systems in the mid-latitudes are caused by instabilities of the jet stream flow (see baroclinity). In Fluid dynamics, the baroclinity (sometimes called baroclinicity) is a measure of the Stratification in a fluid Weather systems in the tropics are caused by different processes, such as monsoons or organized thunderstorm systems. A monsoon is a seasonal prevailing wind which lasts for several months

Because the Earth's axis is tilted relative to its orbital plane, sunlight is incident at different angles at different times of the year. Rotation period Earth's rotation period relative to the Sun (its mean solar day is 86400 Seconds of mean solar time Sunlight, in the broad sense is the total spectrum of the Electromagnetic radiation given off by the Sun. In June the Northern Hemisphere is tilted towards the sun, so at any given Northern Hemisphere latitude sunlight falls more directly on that spot than in December (see Effect of sun angle on climate). The 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 This effect causes seasons. A season is one of the major divisions of the Year, generally based on yearly periodic changes in Weather. Over thousands to hundreds of thousands of years, changes in Earth's orbital parameters affect the amount and distribution of solar energy received by the Earth and influence long-term climate (see Milankovitch cycles). Milankovitch cycles are the collective effect of changes in the Earth 's movements upon its climate named after Serbian civil engineer and Mathematician

Terrestrial weather

Stratocumulus perlucidus clouds

Thunderstorm, Garajau, Madeira

On Earth, common weather phenomena include such things as wind, cloud, rain, snow, fog and dust storms. A stratocumulus Cloud belongs to a class characterized by large dark rounded masses usually in groups lines or waves the individual elements being larger than those in History See also History of Madeira Pre-Portuguese times Pliny mentions certain Purple Islands the position of which with reference to the EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 A meteorological phenomenon is a Weather event which can be explained by the principles of Meteorology. Wind is the flow of Air or other Gases that compose an Atmosphere (including but not limited to the Earth's) A cloud is a visible mass of droplets or frozen crystals floating in the atmosphere above the surface of the Earth or another Planetary body Rain is Liquid precipitation. On Earth it is the condensation of atmospheric Water vapor into drops heavy enough to fall often making it to "Snowfall" redirects here For other uses see Snow (disambiguation or Snowfall (disambiguation. Fog is a cloud that is in contact with the ground Stratus clouds are usually the only clouds that touch the ground Less common events include natural disasters such as tornadoes, hurricanes and ice storms. A natural disaster is the consequence of a Natural hazard (eg A tornado is a violent 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 A tropical cyclone is a storm system characterized by a low pressure center and numerous Thunderstorms that produce strong winds and Flooding A winter storm is an event in which the dominant varieties of precipitation are forms that only occur at cold Temperatures such as Snow or Almost all familiar weather phenomena occur in the troposphere (the lower part of the atmosphere). The troposphere is the lowest portion of Earth's atmosphere. It contains approximately 75% of the atmosphere's mass and almost all of its Water vapor and Weather does occur in the stratosphere and can affect weather lower down in the troposphere, but the exact mechanisms are poorly understood. The stratosphere is the second major layer of Earth's atmosphere, just above the Troposphere, and below the Mesosphere. ^[1]

The atmosphere is a chaotic system, so small changes to one part of the system can grow to have large effects on the system as a whole. Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five In Mathematics, chaos theory describes the behavior of certain dynamical systems – that is systems whose state evolves with time – that may exhibit dynamics that This makes it difficult to accurately predict weather more than a few days in advance, though weather forecasters are continually working to extend this limit through the scientific study of weather, meteorology. Weather forecasting is the application of science and technology to predict the state of the atmosphere for a future time and a given location Meteorology (from Greek grc μετέωρος metéōros, "high in the sky" and grc -λογία -logia) is the Interdisciplinary It is theoretically impossible to make useful day-to-day predictions more than about two weeks ahead, imposing an upper limit to potential for improved prediction skill. [1] Chaos theory says that the slightest variation in the motion of the ground can grow with time. This idea is sometimes called the butterfly effect, from the idea that the motions caused by the flapping wings of a butterfly eventually could produce marked changes in the state of the atmosphere. The butterfly effect is a phrase that encapsulates the more technical notion of sensitive dependence on initial conditions in Chaos theory. Because of this sensitivity to small changes it will never be possible to make perfect forecasts, although there still is much potential for improvement.

The sun and oceans can also affect the weather of land. The Sun (Sol is the Star at the center of the Solar System. An ocean (from Greek, ''Okeanos'' (Oceanus) is a major body of saline water, and a principal component of the Hydrosphere. If the sun heats up ocean waters for a period of time, water can evaporate. Once evaporated into the air, the moisture can spread throughout nearby land, thus making it cooler.

Shaping the planet

Weather is one of the fundamental processes that shape the Earth. The process of weathering breaks down rocks and soils into smaller fragments and then into their constituent substances. Weathering is the decomposition of earth rocks, Soils and their Minerals through direct contact with the planet's Atmosphere. These are then free to take part in chemical reactions that can affect the surface further (e. g. , acid rain) or are reformed into other rocks and soils. Acid rain is Rain or any other form of precipitation that is unusually Acidic It has harmful effects on plants aquatic animals and infastructure Weather also plays a major role in erosion of the surface. Erosion is the carrying away or displacement of solids ( Sediment, Soil, rock and other particles usually by the agents of currents such as wind

Human history

Badly flooded New Orleans, Louisiana after strong category three Hurricane Katrina.

Weather has played a large and sometimes direct part in human history. Prehistory See also Prehistory Paleolithic See also Paleolithic, Recent African Origin, Early Homo sapiens Aside from climatic changes that have caused the gradual drift of populations (for example the desertification of the Middle East, and the formation of land bridges during glacial periods), extreme weather events have caused smaller scale population movements and intruded directly in historical events. Desertification is the degradation of land in arid and dry sub-humid areas resulting primarily from human activities and influenced by climatic variations The Middle East is a Subcontinent with no clear boundaries often used as a synonym to Near East, in opposition to Far East. A land bridge, in Biogeography, is an Isthmus or other land connection between otherwise separate areas which allows Animals and Plants Severe weather is any destructive weather phenomenon. The term is usually used to refer to severe thunderstorms and related phenomena such as Tornados One such event is the saving of Japan from invasion by the Mongol fleet of Kublai Khan by the Kamikaze winds in 1281. For a topic outline on this subject see List of basic Japan topics. Early years Kublai Khan studied Chinese culture and became enamoured of it Kamikaze (神風 is a Japanese word usually translated as divine wind, believed to be a gift from the gods A series of great storms throughout the 13th century caused the powerful English Cinque Ports to be silted up and hence lose their influence. Cinque Ports is also the name of a 1703 Galleon (ship The Confederation of Cinque Ports (sɪŋk pɔrts is a historic series of coastal More recently, Hurricane Katrina forced the temporary abandonment of the entire city of New Orleans, Louisiana in 2005. Hurricane Katrina of the 2005 Atlantic hurricane season was the costliest hurricane, as well as one of the five deadliest in the history of the United States New Orleans (nʲuːˈɔrliənz nʲuːˈɔrlənz French: La Nouvelle-Orléans) is a major United States port city and the largest city in Louisiana

Though weather affects people in drastic ways, it can also affect the human race in simpler ways. The term race or racial group usually refers to the concept of categorizing Humans into Populations or groups on the basis of various sets It has been noted that the human immune system is affected in extreme heat or cold. Mood can also be affected by weather. A mood is a relatively long lasting affective or emotional state

Forecasting

An example of a two-day weather forecast in the visual style that an American newspaper might use. A visual language is a set of practices by which Images can be used to communicate Concepts Overview Creation of an image to communicate The United States of America —commonly referred to as the A newspaper is a written Publication containing News, information and Advertising, usually printed on low-cost paper called Newsprint. The numbers are temperature in degrees Fahrenheit, daytime high to the left and nighttime low to the right. Fahrenheit is a temperature scale named after Daniel Gabriel Fahrenheit (1686–1736 a German Physicist who proposed it in 1724

Weather forecasting is the application of science and technology to predict the state of the atmosphere at a future time. Weather forecasting is the application of science and technology to predict the state of the atmosphere for a future time and a given location Prior to the advent of scientific methods of weather forecasting, a large body of weather folklore developed to explain the weather. Weather lore is the body of informal Folklore related to the Prediction of the Weather. An example is the Groundhog Day celebration near the end of winter in parts of the United States and Canada, which forecasts whether spring is near or far depending on if the groundhog sees his shadow or not. Groundhog Day is a holiday celebrated in United States and Canada on February 2. Today, weather forecasts are made by collecting data that describe the current state of the atmosphere (particularly the temperature, humidity and wind) and using physically-based mathematical models to determine how the atmosphere is expected to change in the future. Numerical weather prediction uses current weather conditions as input into Mathematical models of the atmosphere to predict the weather. The chaotic nature of the atmosphere means that perfect forecasts are impossible, and that forecasts become less accurate as the range of the forecast increases. In Mathematics, chaos theory describes the behavior of certain dynamical systems – that is systems whose state evolves with time – that may exhibit dynamics that The butterfly effect is a phrase that encapsulates the more technical notion of sensitive dependence on initial conditions in Chaos theory.

Weather modification and human impact

The wish to control the weather is evident throughout human history: from ancient rituals intended to bring rain for crops to the U. Weather control is the act of manipulating or altering certain aspects of the environment to produce desirable changes in weather S. Military Operation Popeye, an attempt to disrupt supply lines by lengthening the North Vietnamese monsoon. Operation Popeye (Project Popeye/Motorpool/Intermediary-Compatriot was a US military Cloud seeding operation (running from March 20, 1967 until July Military supply chain management is a cross-functional approach to procuring, producing and delivering products and services The broad A monsoon is a seasonal prevailing wind which lasts for several months The most successful attempts at influencing weather involve cloud seeding; they include the fog- and low stratus dispersion techniques employed by major airports, techniques used to increase winter precipitation over mountains, and techniques to suppress hail. Cloud seeding, a form of weather modification, is the attempt to change the amount or type of precipitation that falls from Clouds by dispersing substances Fog is a cloud that is in contact with the ground Stratus clouds are usually the only clouds that touch the ground Stratus means layer or blanket in Latin A Stratus cloud (St is a Cloud belonging to a class characterized by horizontal layering with a uniform base "Snowfall" redirects here For other uses see Snow (disambiguation or Snowfall (disambiguation. Hail is a form of precipitation which consists of balls or irregular lumps of ice (hailstones ^[2]

Whereas there is inconclusive evidence for these techniques' efficacy, there is extensive evidence that human activity such as agriculture and industry results in inadvertent weather modification:^[3]

• Acid rain, caused by industrial emission of sulfur dioxide and nitrogen oxides into the atmosphere, adversely effects freshwater lakes, vegetation, and structures. Agriculture refers to the production of goods through the growing of plants and fungi and the raising of domesticated Animals The study of agriculture For other uses of this term see Industry (disambiguation An industry (from Latin industrius, "diligent industrious" Acid rain is Rain or any other form of precipitation that is unusually Acidic It has harmful effects on plants aquatic animals and infastructure Exhaust gas is Flue gas which occurs as a result of the Combustion of fuels such as Natural gas, Gasoline /petrol Diesel, Fuel The term nitrogen oxide typically refers to any Binary compound of Oxygen and Nitrogen, or to a mixture of such compounds Nitric An atmosphere (from Greek ατμός - atmos, " Vapor " + σφαίρα - sphaira, " Sphere " A lake (from Latin lacus) is a Terrain feature (or Physical feature) a body of Liquid on the surface of a world that is localized to the Plants are living Organisms belonging to the kingdom Plantae. In Architecture, Construction, Engineering and real estate development the word building may refer to one of the following Any man-made
• Anthropogenic pollutants reduce air quality and visibility. Anthropogenic effects processes objects or materials are those that are derived from Human activities as opposed to those occurring in Natural environments without The Air Quality Index ( AQI) is a standardized indicator of the Air Quality in a given location In Meteorology, visibility is a measure of the Distance at which an object or light can be clearly discerned
• Climate change caused by human activities that emit greenhouse gases into the air is expected to affect the frequency of extreme weather events such as drought, extreme temperatures, flooding, high winds, and severe storms. Climate change is any long-term significant change in the “average weather” that a given region experiences Greenhouse gases are gaseous constituents of the atmosphere bothnatural and anthropogenic that absorb and emit radiation at specific wavelengths within the spectrum of thermal infrared See also List of extreme weather events Extreme weather includes Weather phenomena that are at the extremes of the historical distribution especially A drought is an extended period of months or years when a region notes a deficiency in its water supply A flood is an overflow of an expanse of water that submerges land a deluge Wind is the flow of Air or other Gases that compose an Atmosphere (including but not limited to the Earth's) A storm is any disturbed state of an astronomical body's atmosphere, especially affecting its surface and strongly implying Severe weather. ^[4]

The effects of inadvertent weather modification may pose serious threats to many aspects of civilization, including ecosystems, natural resources, food and fiber production, economic development, and human health. An ecosystem is a natural unit consisting of all plants animals and micro-organisms( Biotic factors in an area functioning together with all of the non-living physical ( Natural resources are naturally occurring substances that are considered valuable in their relatively unmodified ( natural) form Food is any substance usually composed primarily of Carbohydrates Fats water and/or Proteins that can be eaten or drunk by an Fiber or fibre is a class of Materials that are continuous filaments or are in discrete elongated pieces similar to lengths of thread. Economic development is the development of economic wealth of countries or regions for the well-being of their inhabitants Health is a state of complete physical mental and social well-being and not merely the absence of disease or infirmity ^[5].

Extremes

Main article: List of weather records

Early morning sunshine over Bratislava, Slovakia. This is a list of Weather records, a list of the most extreme occurrences of weather phenomena for various categories ARTICLE TEXT BEGINS AFTER THESE COMMENTS - PLEASE READ 1 Please do not edit the lead without reading Slovakia (long form Slovak Republic; Slovak:, long form, is a Landlocked country in Central Europe with a population of over five million

The same area, just three hours later, after heavy snowfall.

On earth, temperatures usually range between ±40 °C. However, the wide range of climates and latitudes offer extremes of temperature well outside this range. The coldest air temperature ever recorded on Earth is -89. 2 °C (-127. 8 °F), at Vostok Station, Antarctica on 21 July 1983. Vostok Station (Станция Восток is a Russian (formerly Soviet) Research station located near the Southern Pole of Inaccessibility Events 356 BC - Herostratus sets fire to the Temple of Artemis in Ephesus, one of the Seven Wonders of the World The hottest air temperature ever recorded was 57. 7 °C (135. 9 °F), at Al 'Aziziyah, Libya, on 13 September 1922. El 'Azizia ( العزيزيه) is one of the municipalities of Libya, located in the Northwest of the country 55 km Southwest of Tripoli Libya ( ليبيا ar-Latn Lībiyā; Libyan vernacular: Lībya; Amazigh:) officially the Great Socialist People's Libyan Arab Events 509 BC - The Temple of Jupiter on Rome 's Capitoline Hill is dedicated on the ides of September The highest recorded average annual temperature was 34. 4 °C (94 °F) at Dallol, Ethiopia. Dallol is a settlement in northern Ethiopia. Located NOTE This intro is the result of careful NPOV work Please do not make potentially controversial edits to it without first discussing on the talk page The coldest recorded average annual temperature is -50. 6 °C (-59 °F) at Vostok Station, Antarctica. Vostok Station (Станция Восток is a Russian (formerly Soviet) Research station located near the Southern Pole of Inaccessibility The coldest average annual temperature in a permanently inhabited location is at Resolute, Nunavut, in Canada. Resolute ( Inuktitut: iu-Latn Qausuittuq ( place with no dawn) sometimes Resolute Bay) is a Country to "Dominion of Canada" or "Canadian Federation" or anything else please read the Talk Page

Extra-terrestrial weather

Jupiter's Great Red Spot

Studying how the weather works on other planets has been seen as helpful in understanding how it works on Earth. ^[6] Weather on other planets follows many of the same physical principles as weather on Earth, but occurs on different scales and in atmospheres having different chemical composition. The Cassini–Huygens mission to Titan discovered clouds formed from methane or ethane which deposit rain composed of liquid methane and other organic compounds. Cassini–Huygens is a joint NASA / ESA / ASI Robotic spacecraft mission currently studying the planet Saturn and its TemplateInfobox Planet.--> Titan (ˈtaɪtən, or as Methane is a Chemical compound with the molecular formula. It is the simplest Alkane, and the principal component of Natural gas. An organic compound is any member of a large class of Chemical compounds whose Molecules contain Carbon. Earth's atmosphere includes about six latitudinal circulation zones, three in each hemisphere (see Hadley cell). The Hadley cell is a circulation pattern that dominates the tropical atmosphere with rising motion near the equator poleward flow 10-15 kilometers above the surface descending motion In contrast Jupiter's banded appearance shows over a dozen such zones, Titan has a single cell covering its entire surface, and Venus appears to have no zones at all. The VENUS ( V ictoria E xperimental N etwork U nder the S ea project is a cabled sea floor observatory operated by the University

One of the most famous landmarks in the Solar System, Jupiter's Great Red Spot, is an anticyclonic storm known to have existed for at least 300 years. The Solar System consists of the Sun and those celestial objects bound to it by Gravity. In Meteorology, an anticyclone (that is opposite to a Cyclone) is a Weather phenomenon in which there is a descending movement of the air and On other gas giants the lack of a surface allows the wind to reach enormous speeds: gusts of up to 400 metres per second (about 1440 km/h / 900 mi/h) have been measured on the planet Neptune. A gas giant (sometimes also known as a Jovian planet after the planet Jupiter, or giant planet) is a large Planet that is not primarily Neptune ( English|AmE] ] is the eighth and farthest Planet from the Sun in the Solar System. This has created a puzzle for planetary scientists. Planetary science, also known as planetology and closely related to planetary astronomy, is the Science of Planets or Planetary systems The weather is ultimately created by solar energy and the amount of energy received by Neptune is only about 1/900th of that received by Earth, yet the intensity of weather phenomena on Neptune is far greater than on Earth. ^[7] The strongest planetary winds discovered so far are on the extrasolar planet HD 189733 b, which is thought to have easterly winds moving at more than 9,600 kilometers per hour. An extrasolar planet, or exoplanet, is a Planet beyond the Solar System, orbiting around other Stars As of September 2008 312 HD 189733 b is an Extrasolar planet approximately 63 Light-years away in the Constellation of Vulpecula (the Fox)

Extra-planetary weather

Aurora Borealis

Main article: Space weather

Weather is not limited to planetary bodies. Space weather is the concept of changing environmental conditions in Outer space. A star's corona is constantly being lost to space, creating what is essentially a very thin atmosphere throughout the Solar System. A corona is a type of plasma " atmosphere " of the Sun or other celestial body extending millions of Kilometres into space most easily The Solar System consists of the Sun and those celestial objects bound to it by Gravity. The movement of mass ejected from the Sun is known as the solar wind. The solar wind is a Stream of charged particles&mdasha plasma &mdashthat are ejected from the upper atmosphere of the Sun.

Inconsistencies in this wind and larger events on the surface of the star, such as coronal mass ejections, form a system that has features analogous to conventional weather systems (such as pressure and wind) and is generally known as space weather. A coronal mass ejection (CME is an ejection of material from the solar Corona, usually observed with a white-light Coronagraph. Space weather is the concept of changing environmental conditions in Outer space. The activity of this system can affect planetary atmospheres and occasionally surfaces. An atmosphere (from Greek ατμός - atmos, " Vapor " + σφαίρα - sphaira, " Sphere " The interaction of the solar wind with the terrestrial atmosphere can produce spectacular aurorae, and can play havoc with electrically sensitive systems such as electricity grids and radio signals. Electric power transmission, a process in the delivery of Electricity to consumers is the bulk transfer of electrical power Radio is the transmission of signals by Modulation of electromagnetic waves with frequencies below those of visible Light.

See also

• Cloud
• Meteorology
• Space weather
• Weather forecasting
• Weather station
• Personal weather station

References

External links

• Ogimet - online data from meteorological stations of the world
• Weather at About.com
• Wunderground (Weather Underground) - online forecast and personal weather station network
• RainRadar - Worldwide radar directory