Editing Weather

{{Short description|Short-term state of the atmosphere}}
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{{About|the atmospheric process|the geological process|Weathering|other uses|Weather (disambiguation)|and|Weather systems (disambiguation)}}
{{redirect|Fair weather|other uses|Fairweather (disambiguation)}}
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{{Use dmy dates|date=February 2020}}

[[File:Port and lighthouse overnight storm with lightning in Port-la-Nouvelle.jpg|thumb|upright=1.35|Thunderstorm near Port-la-Nouvelle, [[France]]]]

{{Weather}}

'''Weather''' is the state of the [[atmosphere]], describing for example the degree to which it is hot or cold, wet or dry, calm or stormy, clear or [[cloud cover|cloudy]].<ref>"[http://www.merriam-webster.com/dictionary/weather Weather.]" ''Merriam-Webster Dictionary''. {{Webarchive|url=https://web.archive.org/web/20170709032002/https://www.merriam-webster.com/dictionary/weather |date=9 July 2017}} Retrieved on 27 June 2008.</ref> On [[Earth]], most weather phenomena occur in the lowest layer of the planet's [[atmosphere of Earth|atmosphere]], the [[troposphere]],<ref>{{cite web |website=Glossary of Meteorology |url=http://amsglossary.allenpress.com/glossary/search?p=1&query=hydrosphere&submit=Search |title=Hydrosphere |archive-url=https://web.archive.org/web/20120315161323/http://amsglossary.allenpress.com/glossary/search?p=1&query=hydrosphere&submit=Search |archive-date=15 March 2012 |access-date=27 June 2008}}</ref><ref name=":0">{{Cite web |title=Troposphere|url=http://amsglossary.allenpress.com/glossary/browse?s=t&p=51|archive-url=https://web.archive.org/web/20120928061111/http://amsglossary.allenpress.com/glossary/browse?s=t&p=51|url-status=dead|archive-date=2012-09-28|access-date=2020-10-11|website=Glossary of Meteorology}}</ref> just below the [[stratosphere]]. Weather refers to day-to-day temperature, [[precipitation]], and other atmospheric conditions, whereas [[climate]] is the term for the averaging of atmospheric conditions over longer periods of time.<ref>{{cite encyclopedia | title = Climate | encyclopedia = Glossary of Meteorology | publisher = [[American Meteorological Society]] | url = http://amsglossary.allenpress.com/glossary/search?id=climate1 | access-date = 14 May 2008 | archive-date = 7 July 2011 | archive-url = https://web.archive.org/web/20110707113544/http://amsglossary.allenpress.com/glossary/search?id=climate1 | url-status = dead }}</ref> When used without qualification, "weather" is generally understood to mean the weather of Earth.

Weather is driven by [[atmospheric pressure|air pressure]], [[temperature]], and [[moisture]] differences between one place and another. These differences can occur due to the [[effect of Sun angle on climate|Sun's angle]] at any particular spot, which varies with [[latitude]]. The strong temperature contrast between polar and tropical air gives rise to the largest scale [[atmospheric circulation]]s: the [[Hadley cell]], the [[Ferrel cell]], the [[polar cells|polar cell]], and the [[jet stream]]. Weather systems in the [[middle latitudes]], such as [[extratropical cyclone]]s, are caused by instabilities of the jet streamflow.  Because Earth's [[axial tilt|axis is tilted]] relative to its [[orbital plane (astronomy)|orbital plane]] (called the [[ecliptic]]), [[sunlight]] is incident at [[Angle of incidence (optics)|different angles]] at different times of the year. On Earth's surface, temperatures usually range ±40&nbsp;°C (−40&nbsp;°F to 104&nbsp;°F) annually. Over thousands of years, changes in Earth's [[orbit]] can affect the amount and distribution of [[solar energy]] received by Earth, thus influencing long-term climate and global [[Climate variability and change|climate change]].

Surface temperature differences in turn cause pressure differences. Higher altitudes are cooler than lower altitudes, as most atmospheric heating is due to contact with the Earth's surface while radiative losses to space are mostly constant. [[Weather forecasting]] is the application of science and technology to predict the state of the [[Earth's atmosphere|atmosphere]] for a future time and a given location. Earth's weather system is a [[chaos theory|chaotic system]]; as a result, small changes to one part of the system can grow to have large effects on the system as a whole. Human attempts to [[weather control|control the weather]] have occurred throughout history, and there is evidence that [[human impact on the environment|human activities]] such as agriculture and industry have modified weather patterns.

Studying how the weather works on other planets has been helpful in understanding how weather works on Earth. A famous landmark in the [[Solar System]], Jupiter's [[Great Red Spot]], is an [[anticyclonic storm]] known to have existed for at least 300 years. However, the weather is not limited to planetary bodies. A [[stellar corona|star's corona]] is constantly being lost to space, creating what is essentially a very thin atmosphere throughout the Solar System. The movement of mass ejected from the [[Sun]] is known as the [[solar wind]].

== Causes ==
[[File:Stormclouds.jpg|thumb|right|upright=1.13|[[Cumulonimbus cloud]] surrounded by [[stratocumulus]]]]
On [[Earth]], common [[List of meteorological phenomena|weather phenomena]] include wind, [[cloud]], rain, snow, [[fog]] and [[dust storm]]s. Some more common events include [[natural disaster]]s such as [[tornado]]es, [[Tropical cyclone|hurricanes]], [[typhoons]] and [[Ice storm|ice storms]]. Almost all familiar weather phenomena occur in the troposphere (the lower part of the atmosphere).<ref name=":0" /> Weather does occur in the stratosphere and can affect weather lower down in the troposphere, but the exact mechanisms are poorly understood.<ref>{{cite web|url=http://www.gsfc.nasa.gov/topstory/20011018windsurface.html |title=Weather Forecasters May Look Sky-high For Answers |last=O'Carroll |first=Cynthia M. |publisher=[[Goddard Space Flight Center]] (NASA) |date=18 October 2001 |url-status=dead |archive-url=https://web.archive.org/web/20090712090309/http://www.gsfc.nasa.gov/topstory/20011018windsurface.html |archive-date=12 July 2009 }}</ref>

Weather occurs primarily due to air pressure, temperature and [[moisture]] differences from one place to another. These differences can occur due to the [[sun]] angle at any particular spot, which varies by latitude in the tropics. In other words, the farther from the tropics one lies, the lower the sun angle is, which causes those locations to be cooler due to the spread of the [[sunlight]] over a greater surface.<ref>[[NASA]]. [https://web.archive.org/web/20050501070321/http://www.nasa.gov/worldbook/weather_worldbook.html World Book at NASA: Weather.] [https://web.archive.org/web/20101213184908/http://www.nasa.gov/worldbook/weather_worldbook.html Archived copy] at [[WebCite]] (10 March 2013). Retrieved on 27 June 2008.</ref> The strong temperature contrast between [[Polar region|polar]] and tropical air gives rise to the large scale [[atmospheric circulation]] cells and the [[jet stream]].<ref name="Stimac">John P. Stimac. [http://www.ux1.eiu.edu/~cfjps/1400/pressure_wind.html] {{Webarchive|url=https://web.archive.org/web/20070927210111/http://www.ux1.eiu.edu/~cfjps/1400/pressure_wind.html|date=27 September 2007}} [[Air pressure]] and wind. Retrieved on 8 May 2008.</ref> Weather [[systems]] in the mid-latitudes, such as [[extratropical cyclone]]s, are caused by instabilities of the [[jet stream]] flow (see [[baroclinity]]).<ref>Carlyle H. Wash, Stacey H. Heikkinen, Chi-Sann Liou, and Wendell A. Nuss. [https://archive.today/20121208181523/http://ams.allenpress.com/perlserv/?request=get-abstract&doi=10.1175/1520-0493(1990)118%3C0234:ARCEDG%3E2.0.CO;2 A Rapid Cyclogenesis Event during GALE IOP 9.] Retrieved on 28 June 2008.</ref> Weather systems in the tropics, such as [[monsoon]]s or organized [[thunderstorm]] systems, are caused by different processes.
[[File:16-008-NASA-2015RecordWarmGlobalYearSince1880-20160120.png|thumb|left|upright=1.36|{{center|2015 – [[Global warming|5th Warmest Global Year]] on Record (since 1880) as of 2021 – Colors indicate temperature anomalies ([[NASA]]/[[NOAA]]; 20 January 2016).<ref name="NASA-20160120">{{cite web |last1=Brown |first1=Dwayne |last2=Cabbage |first2=Michael |last3=McCarthy |first3=Leslie |last4=Norton |first4=Karen |title=NASA, NOAA Analyses Reveal Record-Shattering Global Warm Temperatures in 2015 |url=http://www.nasa.gov/press-release/nasa-noaa-analyses-reveal-record-shattering-global-warm-temperatures-in-2015 |date=20 January 2016 |work=[[NASA]] |access-date=21 January 2016 |archive-date=20 January 2016 |archive-url=https://web.archive.org/web/20160120183259/http://www.nasa.gov/press-release/nasa-noaa-analyses-reveal-record-shattering-global-warm-temperatures-in-2015 |url-status=live }}</ref>}}]]
Because the Earth's [[Earth's rotation|axis]] is tilted relative to its orbital plane, [[sunlight]] is incident at different angles at different times of the year. 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]]).<ref>Windows to the Universe. [http://www.windows.ucar.edu/tour/link=/earth/climate/cli_seasons.html Earth's Tilt Is the Reason for the Seasons!] {{Webarchive|url=https://web.archive.org/web/20070808022809/http://www.windows.ucar.edu/tour/link=/earth/climate/cli_seasons.html |date=8 August 2007 }} Retrieved on 28 June 2008.</ref> This effect causes seasons. 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]]).<ref>Milankovitch, Milutin.  Canon of Insolation and the Ice Age Problem.  Zavod za Udz̆benike i Nastavna Sredstva: Belgrade, 1941. {{ISBN|86-17-06619-9}}.</ref>

The uneven solar heating (the formation of zones of temperature and moisture gradients, or [[frontogenesis]]) can also be due to the weather itself in the form of cloudiness and precipitation.<ref>Ron W. Przybylinski. [http://www.crh.noaa.gov/lsx/science/pdfppt/ron.ppt The Concept of Frontogenesis and its Application to Winter Weather Forecasting.] {{Webarchive|url=https://web.archive.org/web/20131024133948/http://www.crh.noaa.gov/lsx/science/pdfppt/ron.ppt |date=24 October 2013 }} Retrieved on 28 June 2008.</ref> Higher altitudes are typically cooler than lower altitudes, which is the result of higher surface temperature and radiational heating, which produces the [[Adiabatic process|adiabatic]] [[lapse rate]].<ref>{{cite book|author=Mark Zachary Jacobson|title=Fundamentals of Atmospheric Modeling|publisher=Cambridge University Press|edition=2nd|date=2005|isbn=978-0-521-83970-9|oclc=243560910}}</ref><ref>{{cite book|author=C. Donald Ahrens|title=Meteorology Today|publisher=Brooks/Cole Publishing|edition=8th|date=2006|isbn=978-0-495-01162-0|oclc=224863929}}</ref> In some situations, the temperature actually increases with height. This phenomenon is known as an [[Inversion (meteorology)|inversion]] and can cause mountaintops to be warmer than the valleys below. Inversions can lead to the formation of [[fog]] and often act as a [[Capping inversion|cap]] that [[Convective inhibition|suppresses]] thunderstorm development. On local scales, temperature differences can occur because different surfaces (such as oceans, forests, [[ice]] sheets, or human-made objects) have differing physical characteristics such as [[albedo|reflectivity]], roughness, or moisture content.

Surface temperature differences in turn cause pressure differences. A hot surface warms the air above it causing it to expand and lower the density and the resulting surface [[Atmospheric pressure|air pressure]].<ref>Michel Moncuquet. [http://www.lesia.obspm.fr/~moncuque/theseweb/tempioweb/node6.html  Relation between density and temperature.] {{Webarchive|url=https://web.archive.org/web/20221127023536/https://www.lesia.obspm.fr/~moncuque/theseweb/tempioweb/node6.html |date=27 November 2022 }} Retrieved on 28 June 2008.</ref> The resulting horizontal [[Pressure gradient (atmospheric)|pressure gradient]] moves the air from higher to lower pressure regions, creating a wind, and the Earth's rotation then causes deflection of this airflow due to the [[Coriolis effect]].<ref>Encyclopedia of Earth. [http://www.eoearth.org/article/Wind Wind.] {{Webarchive|url=https://web.archive.org/web/20130509073805/http://www.eoearth.org/article/Wind |date=9 May 2013 }} Retrieved on 28 June 2008.</ref> The simple systems thus formed can then display [[Emergence|emergent behaviour]] to produce more [[Pressure system|complex systems]] and thus other weather phenomena.  Large scale examples include the [[Hadley cell]] while a smaller scale example would be [[sea breeze|coastal breezes]].

The [[Earth's atmosphere|atmosphere]] is a [[chaos theory|chaotic system]]. As a result, small changes to one part of the system can accumulate and magnify to cause large effects on the system as a whole.<ref>Spencer Weart. [http://www.aip.org/history/climate/chaos.htm The Discovery of Global Warming.] {{Webarchive|url=https://web.archive.org/web/20110607091743/http://www.aip.org/history/climate/chaos.htm |date=7 June 2011 }} Retrieved on 28 June 2008.</ref> This atmospheric instability makes weather forecasting less predictable than tidal waves or eclipses.<ref name="Lorenz, 1969">{{cite web|last1=Lorenz|first1=Edward|title=How Much Better Can Weather Prediction Become?|url=http://eaps4.mit.edu/research/Lorenz/How_Much_Better_Can_Weather_Prediction_1969.pdf|website=web.mit.edu/|publisher=Massachusetts Institute of Technology|access-date=21 July 2017|date=July 1969|archive-date=17 April 2016|archive-url=https://web.archive.org/web/20160417061111/http://eaps4.mit.edu/research/Lorenz/How_Much_Better_Can_Weather_Prediction_1969.pdf|url-status=dead}}</ref> Although it is difficult to accurately predict weather more than a few days in advance, [[weather forecasting|weather forecasters]] are continually working to extend this limit through [[meteorology|meteorological]] research and refining current methodologies in weather prediction. However, 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.<ref name="Chaos in the Atmosphere">{{cite web|title=The Discovery of Global Warming: Chaos in the Atmosphere|url=https://history.aip.org/climate/chaos.htm|website=history.aip.org|access-date=21 July 2017|date=January 2017|archive-date=28 November 2016|archive-url=https://web.archive.org/web/20161128121540/https://history.aip.org/climate/chaos.htm|url-status=live}}</ref>

==Shaping the planet Earth==
{{Main|Weathering}}
Weather is one of the fundamental processes that shape the Earth. The process of weathering breaks down the rocks and soils into smaller fragments and then into their constituent substances.<ref>[[NASA]]. [http://www.nasa.gov/mission_pages/odyssey/odyssey-20080320.html NASA Mission Finds New Clues to Guide Search for Life on Mars.] {{Webarchive|url=https://web.archive.org/web/20080611112222/http://www.nasa.gov/mission_pages/odyssey/odyssey-20080320.html |date=11 June 2008 }} Retrieved on 28 June 2008.</ref> During rains precipitation, the water droplets absorb and dissolve carbon dioxide from the surrounding air. This causes the rainwater to be slightly acidic, which aids the erosive properties of water. The released sediment and chemicals are then free to take part in [[chemical]] reactions that can affect the surface further (such as [[acid rain]]), and sodium and chloride ions ([[sea salt|salt]]) deposited in the seas/oceans. The sediment may reform in time and by geological forces into other rocks and soils. In this way, weather plays a major role in [[erosion]] of the surface.<ref>West Gulf River Forecast Center. [http://www.srh.noaa.gov/wgrfc/resources/glossary/e.html Glossary of Hydrologic Terms: E] {{Webarchive|url=https://web.archive.org/web/20090116022913/http://www.srh.noaa.gov/wgrfc/resources/glossary/e.html |date=16 January 2009 }} Retrieved on 28 June 2008.</ref>

==Effect on humans==
{{Further|Biometeorology#Human biometeorology|l1=Biometeorology}}
Weather, seen from an anthropological perspective, is something all humans in the world constantly experience through their senses, at least while being outside. There are socially and scientifically constructed understandings of what weather is, what makes it change, the effect the weather, and especially '''inclement weather''', has on humans in different situations, etc.<ref>{{Cite book|title = Anthropology and Climate Change: From Encounters to Actions|editor-last = Crate|editor-first = Susan A|editor2-first = Mark|editor2-last = Nuttall|publisher = Left Coast Press|date = 2009|location = Walnut Creek, CA|pages = 70–86, i.e. the chapter 'Climate and weather discourse in anthropology: from determinism to uncertain futures' by Nicholas Peterson & Kenneth Broad|url = http://www.geos.ed.ac.uk/~nabo/meetings/glthec/groups/group_data/ecodynamics/02_Crate_Ch-02.pdf|access-date = 21 May 2014|archive-date = 27 February 2021|archive-url = https://web.archive.org/web/20210227193115/https://www.geos.ed.ac.uk/~nabo/meetings/glthec/groups/group_data/ecodynamics/02_Crate_Ch-02.pdf|url-status = live}}</ref> Therefore, weather is something people often communicate about.

In the United States, the [[National Weather Service]] has an annual report for fatalities, injury, and total damage costs which include crop and property. They gather this data via National Weather Service offices located throughout the 50 states in the United States as well as [[Puerto Rico]], [[Guam]], and the [[United States Virgin Islands|Virgin Islands]]. As of 2019, tornadoes have had the greatest impact on humans with 42 fatalities while costing crop and property damage over 3 billion dollars.<ref>United States. National Weather Service. Office of Climate, Water, Weather Services, & National Climatic Data Center. (2000). ''Weather Related Fatality and Injury Statistics.''</ref>

===Effects on populations===
[[Image:Navy-FloodedNewOrleans.jpg|thumb|New Orleans, Louisiana, after being struck by [[Hurricane Katrina]]. Katrina was a [[Category 3 hurricane]] when it struck although it had been a category 5 hurricane in the [[Gulf of Mexico]].]]
The weather has played a large and sometimes direct part in [[human history]]. Aside from [[climate change|climatic changes]] that have caused the gradual drift of populations (for example the [[desertification]] of the Middle East, and the formation of [[land bridge]]s during [[glacial]] periods), [[Severe weather|extreme weather]] events have caused smaller scale population movements and intruded directly in historical events. One such event is the saving of Japan from invasion by the [[Mongols|Mongol]] fleet of [[Kublai Khan]] by the [[Kamikaze (typhoon)|Kamikaze]] winds in 1281.<ref>James P. Delgado. [http://www.archaeology.org/0301/etc/kamikaze.html Relics of the Kamikaze.] {{Webarchive|url=https://web.archive.org/web/20110306115219/http://www.archaeology.org/0301/etc/kamikaze.html |date=6 March 2011 }} Retrieved on 28 June 2008.</ref> French claims to Florida came to an end in 1565 when a hurricane destroyed the French fleet, allowing Spain to conquer [[Fort Caroline]].<ref>Mike Strong. [http://www.mikestrong.com/fortcar/ Fort Caroline National Memorial.] {{webarchive|url=https://web.archive.org/web/20121117064301/http://www.mikestrong.com/fortcar/ |date=17 November 2012 }} Retrieved on 28 June 2008.</ref> More recently, [[Hurricane Katrina]] redistributed over one million people from the central [[Gulf coast]] elsewhere across the United States, becoming the largest [[diaspora]] in the history of the United States.<ref>Anthony E. Ladd, John Marszalek, and Duane A. Gill. [http://www.ssrc.msstate.edu/katrina/publications/katrinastudentsummary.pdf The Other Diaspora: New Orleans Student Evacuation Impacts and Responses Surrounding Hurricane Katrina.] {{webarchive|url=https://web.archive.org/web/20080624185024/http://www.ssrc.msstate.edu/katrina/publications/katrinastudentsummary.pdf |date=24 June 2008 }} Retrieved on 29 March 2008.</ref>

The [[Little Ice Age]] caused crop failures and [[famine]]s in Europe. During the period known as the [[Grindelwald Fluctuation]] (1560–1630), volcanic forcing events<ref>Jason Wolfe, [https://earthdata.nasa.gov/learn/sensing-our-planet/volcanoes-and-climate-change Volcanoes and Climate Change] {{Webarchive|url=https://web.archive.org/web/20210529200210/https://earthdata.nasa.gov/learn/sensing-our-planet/volcanoes-and-climate-change |date=29 May 2021 }}, NASA, 28 July 2020). Date retrieved: 28 May 2021.</ref> seem to have led to more extreme weather events.<ref>{{Cite journal|title=Weird weather in Bristol during the Grindelwald Fluctuation (1560–1630)|first1=Evan T.|last1=Jones|first2=Rose|last2=Hewlett|first3=Anson W.|last3=Mackay|date=5 May 2021|journal=Weather|volume=76|issue=4|pages=104–110|doi=10.1002/wea.3846|bibcode=2021Wthr...76..104J|s2cid=225239334|doi-access=free|hdl=1983/28c52f89-91be-4ae4-80e9-918cd339da95|hdl-access=free}}</ref> These included droughts, storms and unseasonal blizzards, as well as causing the Swiss [[Lower Grindelwald Glacier|Grindelwald Glacier]] to expand. The 1690s saw the worst famine in France since the Middle Ages. Finland suffered a severe famine in 1696–1697, during which about one-third of the Finnish population died.<ref>"''[https://books.google.com/books?id=RiLjHZdt-sMC&pg=PA21 Famine in Scotland: The 'Ill Years' of the 1690s]''". Karen J. Cullen (2010). [[Edinburgh University Press]]. p. 21. {{ISBN|0-7486-3887-3}}</ref>

== Forecasting ==
{{Main|Weather forecasting}}
[[Image:Day5pressureforecast.png|thumb|right|Forecast of surface pressures five days into the future for the north Pacific, North America, and the north Atlantic Ocean as on 9 June 2008]]

Weather forecasting is the application of science and technology to predict the state of the [[Earth's atmosphere|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.<ref>Eric D. Craft. [http://eh.net/encyclopedia/article/craft.weather.forcasting.history ''An Economic History of Weather Forecasting''.] {{webarchive|url=https://web.archive.org/web/20070503193324/http://eh.net/encyclopedia/article/craft.weather.forcasting.history |date=3 May 2007 }} Retrieved on 15 April 2007.</ref> Weather forecasts are made by collecting [[quantitative data]] about the current state of the atmosphere and using [[meteorology|scientific understanding of atmospheric processes]] to project how the atmosphere will evolve.<ref>[[NASA]]. [http://earthobservatory.nasa.gov/Library/WxForecasting/wx2.html Weather Forecasting Through the Ages.] {{Webarchive|url=https://web.archive.org/web/20050910210732/http://earthobservatory.nasa.gov/Library/WxForecasting/wx2.html |date=10 September 2005 }} Retrieved on 25 May 2008.</ref>

Once an all-human endeavor based mainly upon changes in [[Atmospheric pressure|barometric pressure]], current weather conditions, and sky condition,<ref>Weather Doctor. [http://www.islandnet.com/~see/weather/eyes/barometer3.htm Applying The Barometer To Weather Watching.] {{Webarchive|url=https://web.archive.org/web/20080509105153/http://www.islandnet.com/~see/weather/eyes/barometer3.htm |date=9 May 2008 }} Retrieved on 25 May 2008.</ref><ref>Mark Moore. [http://www.nwac.us/education_resources/Field_forecasting.pdf Field Forecasting: A Short Summary.] {{webarchive|url=https://web.archive.org/web/20090325034756/http://www.nwac.us/education_resources/Field_forecasting.pdf |date=25 March 2009 }} Retrieved on 25 May 2008.</ref> [[numerical weather prediction|forecast models]] are now used to determine future conditions. On the other hand, human input is still required to pick the best possible forecast model to base the forecast upon, which involves many disciplines such as pattern recognition skills, [[teleconnection]]s, knowledge of model performance, and knowledge of model biases.

The [[chaos theory|chaotic]] nature of the atmosphere, the massive computational power required to solve the equations that describe the atmosphere, the error involved in measuring the initial conditions, and an incomplete understanding of atmospheric processes mean that forecasts become less accurate as of 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 helps to narrow the error and pick the most likely outcome.<ref name="Klaus">Klaus Weickmann, Jeff Whitaker, Andres Roubicek and Catherine Smith. [http://www.cdc.noaa.gov/spotlight/12012001/ The Use of Ensemble Forecasts to Produce Improved Medium Range (3–15 days) Weather Forecasts.] {{Webarchive|url=https://web.archive.org/web/20071215055130/http://www.cdc.noaa.gov/spotlight/12012001/ |date=15 December 2007 }} Retrieved on 16 February 2007.</ref><ref name="TBK">Todd Kimberlain. [http://www.wpc.ncep.noaa.gov/research/TropicalTalk.ppt Tropical cyclone motion and intensity talk (June 2007).] {{Webarchive|url=https://web.archive.org/web/20210227154914/http://www.wpc.ncep.noaa.gov/research/TropicalTalk.ppt |date=27 February 2021 }} Retrieved on 21 July 2007.</ref><ref>Richard J. Pasch, Mike Fiorino, and [[Chris Landsea]]. [http://www.emc.ncep.noaa.gov/research/NCEP-EMCModelReview2006/TPC-NCEP2006.ppt TPC/NHC’S Review of the NCEP Production Suite For 2006.]{{dead link|date=January 2018 |bot=InternetArchiveBot |fix-attempted=yes }} Retrieved on 5 May 2008.</ref>

There are a variety of end users to weather forecasts. Weather warnings are important forecasts because they are used to protect life and property.<ref>[[National Weather Service]]. [http://www.weather.gov/mission.shtml National Weather Service Mission Statement.] {{webarchive|url=https://web.archive.org/web/20131124214601/http://www.weather.gov/mission.shtml |date=24 November 2013 }} Retrieved on 25 May 2008.</ref><ref>{{Cite web |url=http://www.meteo.si/met/en/app/webmet/#webmet==8Sdwx2bhR2cv0WZ0V2bvEGcw9ydlJWblR3LwVnaz9Ccy92ZvIXZhxWbvkWbhdWZvA3bp5GdugXbsxXZ1J3bwVGfp1WYnVGf7R2btFWaupzJzx2b2VmbpF2JsAXYyFWblRXZypzJTFEVFxETJRVRfxUQUV0UUdSf; |title=National Meteorological Service of Slovenia |access-date=25 February 2012 |archive-url=https://web.archive.org/web/20120618145647/http://www.meteo.si/met/en/app/webmet/#webmet==8Sdwx2bhR2cv0WZ0V2bvEGcw9ydlJWblR3LwVnaz9Ccy92ZvIXZhxWbvkWbhdWZvA3bp5GdugXbsxXZ1J3bwVGfp1WYnVGf7R2btFWaupzJzx2b2VmbpF2JsAXYyFWblRXZypzJTFEVFxETJRVRfxUQUV0UUdSf; |archive-date=18 June 2012 |url-status=dead }}</ref> Forecasts based on temperature and [[Precipitation (meteorology)|precipitation]] are important to agriculture,<ref>Blair Fannin. [http://southwestfarmpress.com/news/061406-Texas-weather/ Dry weather conditions continue for Texas.] {{webarchive|url=https://web.archive.org/web/20090703095038/http://southwestfarmpress.com/news/061406-Texas-weather/ |date=3 July 2009 }} Retrieved on 26 May 2008.</ref><ref>Dr. Terry Mader. [http://beef.unl.edu/stories/200004030.shtml Drought Corn Silage.] {{webarchive|url=https://web.archive.org/web/20111005203246/http://beef.unl.edu/stories/200004030.shtml |date=5 October 2011 }} Retrieved on 26 May 2008.</ref><ref>Kathryn C. Taylor. [http://pubs.caes.uga.edu/caespubs/pubcd/C877.htm Peach Orchard Establishment and Young Tree Care.] {{webarchive|url=https://web.archive.org/web/20081224112403/http://pubs.caes.uga.edu/caespubs/pubcd/C877.htm |date=24 December 2008 }} Retrieved on 26 May 2008.</ref><ref>[[Associated Press]]. [https://query.nytimes.com/gst/fullpage.html?res=9D0CE5DB1E30F937A25752C0A967958260  After Freeze, Counting Losses to Orange Crop.] {{Webarchive|url=https://web.archive.org/web/20210331130921/https://www.nytimes.com/1991/01/14/us/after-freeze-counting-losses-to-orange-crop.html |date=31 March 2021 }} Retrieved on 26 May 2008.</ref> and therefore to commodity traders within stock markets. Temperature forecasts are used by utility companies to estimate demand over coming days.<ref>[[The New York Times]]. [https://query.nytimes.com/gst/fullpage.html?res=9F0CE7D9123AF935A15751C0A965958260  Futures/Options; Cold Weather Brings Surge In Prices of Heating Fuels.] {{Webarchive|url=https://web.archive.org/web/20231214135805/https://www.nytimes.com/1993/02/26/business/futures-options-cold-weather-brings-surge-in-prices-of-heating-fuels.html |date=14 December 2023 }} Retrieved on 25 May 2008.</ref><ref>[[BBC]]. [http://news.bbc.co.uk/1/hi/uk/5212724.stm Heatwave causes electricity surge.] {{Webarchive|url=https://web.archive.org/web/20090520060913/http://news.bbc.co.uk/1/hi/uk/5212724.stm |date=20 May 2009 }} Retrieved on 25 May 2008.</ref><ref>Toronto Catholic Schools. [http://www.tcdsb.org/environment/energydrill/EDSP_KeyMessages_FINAL.pdf The Seven Key Messages of the Energy Drill Program.] {{webarchive|url=https://web.archive.org/web/20120217042744/http://www.tcdsb.org/environment/energydrill/EDSP_KeyMessages_FINAL.pdf |date=17 February 2012 }} Retrieved on 25 May 2008.</ref>

In some areas, people use weather forecasts to determine what to wear on a given day. Since outdoor activities are severely curtailed by heavy [[rain]], [[snow]] and the [[wind chill]], forecasts can be used to plan activities around these events and to plan ahead to survive through them.

Tropical weather forecasting is different from that at higher latitudes. The sun shines more directly on the tropics than on higher latitudes (at least on average over a year), which makes the tropics warm (Stevens 2011). And, the vertical direction (up, as one stands on the Earth's surface) is perpendicular to the Earth's axis of rotation at the equator, while the axis of rotation and the vertical are the same at the pole; this causes the Earth's rotation to influence the atmospheric circulation more strongly at high latitudes than low latitudes. Because of these two factors, clouds and rainstorms in the tropics can occur more spontaneously compared to those at higher latitudes, where they are more tightly controlled by larger-scale forces in the atmosphere. Because of these differences, clouds and rain are more difficult to forecast in the tropics than at higher latitudes. On the other hand, the temperature is easily forecast in the tropics, because it does not change much.<ref>{{Cite web|url=https://www.nature.com/scitable/knowledge/library/tropical-weather-84224797/|title=Tropical Weather {{!}} Learn Science at Scitable|website=nature.com|access-date=2020-02-08|archive-date=8 September 2020|archive-url=https://web.archive.org/web/20200908161720/https://www.nature.com/scitable/knowledge/library/tropical-weather-84224797/|url-status=live}}</ref>

==Modification==
The aspiration to [[Weather modification|control the weather]] is evident throughout human history: from ancient rituals intended to bring rain for crops to the U.S. Military [[Operation Popeye]], an attempt to disrupt [[Military supply chain management|supply lines]] by lengthening the North Vietnamese [[monsoon]]. The most successful attempts at influencing weather involve [[cloud seeding]]; they include the [[fog]]- and low [[Stratus cloud|stratus]] dispersion techniques employed by major airports, techniques used to increase [[snow|winter precipitation]] over mountains, and techniques to suppress [[hail]].<ref name="AMS">{{Cite web|url=https://www.ametsoc.org/index.cfm/ams/404/|archiveurl=https://web.archive.org/web/20100612213920/http://ametsoc.org/policy/wxmod98.html|url-status=dead|title=Planned and Inadvertent Weather Modification|archivedate=12 June 2010|publisher=American Meteorological Society}}</ref> A recent example of weather control was China's preparation for the [[2008 Summer Olympics|2008 Summer Olympic Games]]. China shot 1,104 rain dispersal rockets from 21 sites in the city of [[Beijing]] in an effort to keep rain away from the opening ceremony of the games on 8 August 2008. Guo Hu, head of the Beijing Municipal Meteorological Bureau (BMB), confirmed the success of the operation with 100 millimeters falling in [[Baoding]] City of [[Hebei Province]], to the southwest and Beijing's [[Fangshan District]] recording a rainfall of 25 millimeters.<ref>{{cite news   | last = Huanet | first = Xin| title = Beijing disperses rain to dry Olympic night| publisher = Chinaview| date = 9 August 2008| url = http://news.xinhuanet.com/english/2008-08/09/content_9079637.htm| archive-url = https://web.archive.org/web/20080812000752/http://news.xinhuanet.com/english/2008-08/09/content_9079637.htm| url-status = dead| archive-date = 12 August 2008| access-date =24 August 2008 }}</ref>

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:<ref name="AMS" />
* [[Acid rain]], caused by industrial [[Exhaust gas|emission]] of [[sulfur dioxide]] and [[nitrogen oxide]]s into the [[atmosphere]], adversely affects [[lake|freshwater lakes]], [[plant|vegetation]], and [[building|structures]].
* [[human impact on the environment|Anthropogenic]] pollutants reduce [[Air quality index|air quality]] and [[visibility]].
* [[Climate change]] caused by human activities that emit [[greenhouse gas]]es into the air is expected to affect the frequency of [[extreme weather]] events such as drought, extreme temperatures, [[flood]]ing, high winds, and [[storm|severe storms]].<ref>{{Cite web|url=https://www.grida.no/climate/ipcc/regional/226.htm|title=The Regional Impacts of Climate Change|website=grida.no|access-date=14 May 2023|archive-date=24 March 2023|archive-url=https://web.archive.org/web/20230324041320/https://www.grida.no/climate/ipcc/regional/226.htm|url-status=live}}</ref>
* [[Heat]], generated by large metropolitan areas have been shown to minutely affect nearby weather, even at distances as far as {{convert|1600|km}}.<ref>{{cite web| last = Zhang| first = Guang| title = Cities Affect Temperatures for Thousands of Miles| website = ScienceDaily| date = 28 January 2012| url = https://www.sciencedaily.com/releases/2013/01/130127134210.htm| access-date = 9 March 2018| archive-date = 4 March 2021| archive-url = https://web.archive.org/web/20210304085357/http://www.sciencedaily.com/releases/2013/01/130127134210.htm| url-status = live}}</ref>

The effects of inadvertent weather modification may pose serious threats to many aspects of civilization, including [[ecosystem]]s, [[natural resource]]s, food and fiber production, [[economic development]], and human health.<ref>{{Cite web|url=https://www.grida.no/climate/ipcc/regional/503.htm|title=The Regional Impacts of Climate Change|website=grida.no|access-date=14 May 2023|archive-date=14 May 2023|archive-url=https://web.archive.org/web/20230514205522/https://www.grida.no/climate/ipcc/regional/503.htm|url-status=live}}</ref>

==Microscale meteorology==
[[Microscale meteorology]] is the study of short-lived [[Earth's atmosphere|atmospheric]] phenomena smaller than [[mesoscale meteorology|mesoscale]], about 1&nbsp;km or less. These two branches of [[meteorology]] are sometimes grouped together as "mesoscale and microscale meteorology" (MMM) and together study all phenomena smaller than [[Synoptic scale meteorology|synoptic scale]]; that is they study features generally too small to be depicted on a [[weather map]]. These include small and generally fleeting cloud "puffs" and other small cloud features.<ref>{{cite book | last = Rogers | first = R. | title = A Short Course in Cloud Physics | publisher = Butterworth-Heinemann | location = Oxford | date = 1989 | isbn = 978-0-7506-3215-7 | pages = 61–62}}</ref>

==Extremes on Earth==
[[File:07 July - Percent of global area at temperature records - Global warming - NOAA.svg|thumb | In recent decades, new high temperature records have substantially outpaced new low temperature records on a growing portion of Earth's surface<ref name=NOAA_July>{{cite web |title=Mean Monthly Temperature Records Across the Globe / Timeseries of Global Land and Ocean Areas at Record Levels for July from 1951-2023 |url=https://www.ncei.noaa.gov/access/monitoring/monthly-report/global/202307/supplemental/page-3 |website=NCEI.NOAA.gov |publisher=National Centers for Environmental Information (NCEI) of the National Oceanic and Atmospheric Administration (NOAA)|archive-url=https://web.archive.org/web/20230814224818/https://www.ncei.noaa.gov/access/monitoring/monthly-report/global/202307/supplemental/page-3 |archive-date=14 August 2023 |date=August 2023 |url-status=live}} (change "202307" in URL to see years other than 2023, and months other than 07=July)</ref>]]
{{Main|Extremes on Earth|List of weather records}}

On Earth, temperatures usually range ±40&nbsp;°C (100&nbsp;°F to −40&nbsp;°F) annually. The range of climates and latitudes across the planet can offer extremes of temperature outside this range. The coldest air temperature ever recorded on Earth is {{convert|-89.2|C|F}}, at [[Vostok Station]], Antarctica on 21 July 1983. The hottest air temperature ever recorded was {{convert|57.7|C|F}} at [[ʽAziziya]], Libya, on 13 September 1922,<ref name="NCDC">[http://www.ncdc.noaa.gov/oa/climate/globalextremes.html Global Measured Extremes of Temperature and Precipitation.] {{Webarchive|url=https://archive.today/20120525195312/http://www.ncdc.noaa.gov/oa/climate/globalextremes.html |date=25 May 2012 }} [[National Climatic Data Center]]. Retrieved on 21 June 2007.</ref> but that reading was [['Aziziya#Geography and climate|deemed illegitimate]] by the [[World Meteorological Organization]]. The highest recorded average annual temperature was {{convert|34.4|C|F}} at [[Dallol, Ethiopia|Dallol]], Ethiopia.<ref>Glenn Elert. [http://hypertextbook.com/facts/2000/MichaelLevin.shtml Hottest Temperature on Earth.] {{Webarchive|url=https://web.archive.org/web/20210214045855/https://hypertextbook.com/facts/2000/MichaelLevin.shtml |date=14 February 2021 }} Retrieved on 28 June 2008.</ref> The coldest recorded average annual temperature was {{convert|-55.1|C|F}} at [[Vostok Station]], Antarctica.<ref>Glenn Elert. [http://hypertextbook.com/facts/2000/YongLiLiang.shtml Coldest Temperature On Earth.] {{Webarchive|url=https://web.archive.org/web/20070910101217/http://hypertextbook.com/facts/2000/YongLiLiang.shtml |date=10 September 2007 }} Retrieved on 28 June 2008.</ref>

The coldest average annual temperature in a permanently inhabited location is at [[Eureka, Nunavut]], in Canada, where the annual average temperature is {{convert|-19.7|C|F}}.<ref>{{Cite web |url=http://www.climate.weatheroffice.ec.gc.ca/climate_normals/results_e.html?Province=ALL&StationName=Eureka&SearchType=BeginsWith&LocateBy=Province&Proximity=25&ProximityFrom=City&StationNumber=&IDType=MSC&CityName=&ParkName=&LatitudeDegrees=&LatitudeMinutes=&LongitudeDegrees=&LongitudeMinutes=&NormalsClass=A&SelNormals=&StnId=1750& |title=Canadian Climate Normals 1971–2000 – Eureka |access-date=28 June 2008 |archive-date=11 November 2007 |archive-url=https://web.archive.org/web/20071111091104/http://www.climate.weatheroffice.ec.gc.ca/climate_normals/results_e.html?Province=ALL&StationName=Eureka&SearchType=BeginsWith&LocateBy=Province&Proximity=25&ProximityFrom=City&StationNumber=&IDType=MSC&CityName=&ParkName=&LatitudeDegrees=&LatitudeMinutes=&LongitudeDegrees=&LongitudeMinutes=&NormalsClass=A&SelNormals=&StnId=1750& |url-status=dead }}</ref>

The windiest place ever recorded is in Antarctica, [[Commonwealth Bay]] ([[George V Coast]]). Here the gales reach {{convert|199|mph|km/h|abbr=on|lk=out}}.<ref>{{Cite web |date=2020-09-10 |title=The Places with the Most Extreme Climates |url=https://www.inkermannyc.com/blogs/news/the-places-with-the-most-extreme-climates |access-date=2024-04-05 |website=Inkerman™ |language=en |archive-date=5 April 2024 |archive-url=https://web.archive.org/web/20240405221407/https://www.inkermannyc.com/blogs/news/the-places-with-the-most-extreme-climates |url-status=dead }}</ref> Furthermore, the greatest [[snow]]fall in a period of twelve [[month]]s occurred in [[Mount Rainier]], Washington, US. It was recorded as {{convert|31102|mm|ft|abbr=on|2}} of snow.<ref>{{Cite web|url=https://www.guinnessworldrecords.com/world-records/66569-greatest-snowfall-in-12-months|title=Greatest snowfall in 12 months|website=Guinness World Records|date=18 February 1972|access-date=11 February 2021|archive-date=4 August 2020|archive-url=https://web.archive.org/web/20200804170525/https://www.guinnessworldrecords.com/world-records/66569-greatest-snowfall-in-12-months|url-status=live}}</ref>

==Extraterrestrial weather==
[[Image:Great Red Spot From Voyager 1.jpg|thumb|Jupiter's Great Red Spot in February 1979, photographed by the uncrewed ''[[Voyager 1]]'' NASA space probe.]]
Studying how the weather works on other planets has been seen as helpful in understanding how it works on Earth.<ref>{{cite web|url=http://www.space.com/scienceastronomy/solarsystem/solar_system_weather_010306-1.html |title=The Worst Weather in the Solar System |last=Britt |first=Robert Roy |date=6 March 2001 |publisher=[[Space.com]] |url-status=dead |archive-url=https://web.archive.org/web/20010502142934/http://www.space.com/scienceastronomy/solarsystem/solar_system_weather_010306-1.html |archive-date=2 May 2001 }}</ref> 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 (moon)|Titan]] discovered clouds formed from methane or ethane which deposit rain composed of liquid [[methane]] and other [[organic compound]]s.<ref>{{cite journal | display-authors= 6 | author= M. Fulchignoni | author2= F. Ferri | author3= F. Angrilli| author4= A. Bar-Nun | author5= M.A. Barucci| author6= G. Bianchini | author7= W. Borucki| author8= M. Coradini | author9= A. Coustenis| author10= P. Falkner | author11= E. Flamini| author12= R. Grard | author13= M. Hamelin | author14= A.M. Harri | author15= G.W. Leppelmeier| author16= J.J. Lopez-Moreno | author17= J.A.M. McDonnell| author18= C.P. McKay | author19= F.H. Neubauer | author20= A. Pedersen | author21= G. Picardi| author22= V. Pirronello | author23= R. Rodrigo| author24= K. Schwingenschuh | author25= A. Seiff| author26= H. Svedhem | author27= V. Vanzani | author28= J. Zarnecki | name-list-style= amp | title= The Characterisation of Titan's Atmospheric Physical Properties by the Huygens Atmospheric Structure Instrument (Hasi) | journal=Space Science Reviews| date=2002  | volume=104 | issue= 1 | pages=395–431 |doi=10.1023/A:1023688607077|bibcode = 2002SSRv..104..395F | s2cid= 189778612 }}</ref> Earth's atmosphere includes six latitudinal circulation zones, three in each hemisphere.<ref>[[Jet Propulsion Laboratory]]. [http://sealevel.jpl.nasa.gov/overview/climate-climatic.html  Overview – Climate: The Spherical Shape of the Earth: Climatic Zones.] {{webarchive|url=https://web.archive.org/web/20090726195829/http://sealevel.jpl.nasa.gov/overview/climate-climatic.html |date=26 July 2009 }} Retrieved on 28 June 2008.</ref> In contrast, [[Jupiter|Jupiter's]] banded appearance shows many such zones,<ref>Anne Minard. [https://web.archive.org/web/20080127125248/http://news.nationalgeographic.com/news/2008/01/080123-jupiter-jets.html Jupiter's "Jet Stream" Heated by Surface, Not Sun.] Retrieved on 28 June 2008.</ref> Titan has a single jet stream near the 50th parallel north latitude,<ref>ESA: Cassini–Huygens. [http://www.esa.int/esaMI/Cassini-Huygens/SEMQO5SMTWE_0.html The jet stream of Titan.] {{Webarchive|url=https://web.archive.org/web/20120125191625/http://www.esa.int/esaMI/Cassini-Huygens/SEMQO5SMTWE_0.html |date=25 January 2012 }} Retrieved on 28 June 2008.</ref> and [[Venus]] has a single jet near the equator.<ref>[[Georgia State University]]. [http://hyperphysics.phy-astr.gsu.edu/hbase/Solar/venusenv.html The Environment of Venus.] {{Webarchive|url=https://web.archive.org/web/20190307062424/http://hyperphysics.phy-astr.gsu.edu/hbase/Solar/venusenv.html |date=7 March 2019 }} Retrieved on 28 June 2008.</ref>

One of the most famous landmarks in the [[Solar System]], Jupiter's [[Great Red Spot]], is an [[Anticyclone|anticyclonic]] storm known to have existed for at least 300 years.<ref name="HaydPlan">{{cite web
 |title=Jupiter's Great Red Spot
 |author=Ellen Cohen
 |publisher=Hayden Planetarium
 |url=http://haydenplanetarium.org/resources/ava/page/index.php?file=P0413jupispot
 |access-date=16 November 2007
 |url-status=dead
 |archive-url=https://web.archive.org/web/20070808130633/http://haydenplanetarium.org/resources/ava/page/index.php?file=P0413jupispot
 |archive-date=8 August 2007
}}</ref> On other [[giant planet]]s, the lack of a surface allows the wind to reach enormous speeds: gusts of up to 600&nbsp;metres per second (about {{convert|2100|km/h|mph|abbr=on|disp=or}}) have been measured on the planet [[Neptune]].<ref name="Suomi1991">{{cite journal
 | last=Suomi | first=V.E.
 |author2=Limaye, S.S. |author3=Johnson, D.R.  | date=1991
 | title=High Winds of Neptune: A possible mechanism
 | journal=[[Science (journal)|Science]] | volume=251
 | issue=4996 | pages=929–932 | doi=10.1126/science.251.4996.929
 | pmid=17847386
 | bibcode=1991Sci...251..929S| s2cid=46419483
 }}</ref> This has created a puzzle for [[Planetary science|planetary scientists]]. The weather is ultimately created by solar energy and the amount of energy received by Neptune is only about {{frac|900}} of that received by Earth, yet the intensity of weather phenomena on Neptune is far greater than on Earth.<ref>{{cite web|url=http://hubblesite.org/newscenter/newsdesk/archive/releases/1998/34/text/|title=Hubble Provides a Moving Look at Neptune's Stormy Disposition|last=Sromovsky|first=Lawrence A.|publisher=HubbleSite|date=14 October 1998|access-date=6 January 2006|archive-date=11 October 2008|archive-url=https://web.archive.org/web/20081011172657/http://hubblesite.org/newscenter/newsdesk/archive/releases/1998/34/text/|url-status=live}}</ref> {{As of|2007}}, the strongest planetary winds discovered are on the [[extrasolar planet]] [[HD 189733 b]], which is thought to have easterly winds moving at more than {{convert|9600|km/h|mph}}.<ref name="Knutson">{{cite journal| journal=Nature| volume= 447| pages= 183–186| date=10 May 2007| doi= 10.1038/nature05782| title=A map of the day–night contrast of the extrasolar planet HD 189733b| first=Heather A.| display-authors=6| last=Knutson| author2= David Charbonneau| author3= Lori E. Allen| author4= Jonathan J. Fortney| author5= Eric Agol| author6= Nicolas B. Cowan| author7= Adam P. Showman| author8= Curtis S. Cooper| author9= S. Thomas Megeath| name-list-style= amp| pmid=17495920| issue=7141| bibcode=2007Natur.447..183K|arxiv = 0705.0993 | s2cid= 4402268}}</ref>

==Space weather==
[[File:Polarlicht.jpg|thumb|right|[[Aurora borealis]]]]
{{Main|Space weather}}
Weather is not limited to planetary bodies. Like all stars, the [[solar corona|Sun's corona]] is constantly being lost to space, creating what is essentially a very thin [[atmosphere]] throughout the [[Solar System]]. The movement of mass ejected from the Sun is known as the [[solar wind]]. Inconsistencies in this wind and larger events on the surface of the star, such as [[coronal mass ejection]]s, form a system that has features analogous to conventional weather systems (such as pressure and wind) and is generally known as [[space weather]]. Coronal mass ejections have been tracked as far out in the [[Solar System]] as [[Saturn]].<ref>Bill Christensen. [http://www.space.com/businesstechnology/technology/technovel_shock_041105.html Shock to the (Solar) System: Coronal Mass Ejection Tracked to Saturn.] {{Webarchive|url=https://web.archive.org/web/20110101202451/http://www.space.com/businesstechnology/technology/technovel_shock_041105.html |date=1 January 2011 }} Retrieved on 28 June 2008.</ref> The activity of this system can affect planetary [[atmosphere]]s and occasionally surfaces. The interaction of the [[solar wind]] with the terrestrial atmosphere can produce spectacular [[Aurora (astronomy)|aurorae]],<ref>AlaskaReport. [http://alaskareport.com/science10043.htm What Causes the Aurora Borealis?] {{Webarchive|url=https://web.archive.org/web/20160303231153/http://alaskareport.com/science10043.htm |date=3 March 2016 }} Retrieved on 28 June 2008.</ref> and can play havoc with electrically sensitive systems such as [[Electric power transmission|electricity grids]] and radio signals.<ref>{{cite web|first=Rodney|last=Viereck|date=Summer 2007|url=https://lasp.colorado.edu/media/education/reu/2007/docs/talks/SW_Intro_Viereck.ppt|title=Space Weather: What is it? How Will it Affect You?|website=[[Laboratory for Atmospheric and Space Physics]] at [[University of Colorado Boulder]]|access-date=28 June 2008|quote=powerpoint download|archive-date=23 October 2015|archive-url=https://web.archive.org/web/20151023184243/http://lasp.colorado.edu/media/education/reu/2007/docs/talks/SW_Intro_Viereck.ppt|url-status=live}}</ref>

==See also==
* [[Glossary of meteorology]]
* [[Indigenous Australian seasons]]
* [[Outline of meteorology]]
* [[Weather station]]
* [[Weather of {{CURRENT YEAR}}]]

==References==
{{Reflist}}

==External links==
* {{Commons category-inline|Weather}}<!-- Do not add your local weather service.  Wikipedia is not a link directory. -->
* {{Wikiquote-inline}}
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{{Nature}}
{{Earth}}
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[[Category:Weather| ]]