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{{Short description|Natural movement of air or other gases relative to a planet's surface}}
{{Other uses}}
{{Pp-move-indef}}
[[File:Cherry tree moving in the wind 1.gif|thumb|upright=1.35|Cherry tree moving with the wind blowing about 22 m/sec (about 79 km/h or 49 mph)]]
[[File:Wind in Swedish pine forest at 25 mps.ogg|thumb|Sound of wind blowing in a pine forest at around 25 m/sec, with [[Wind gust|gust]] alterations]]
'''Wind''' is the natural movement of [[atmosphere of Earth|air]] or other [[gas]]es relative to a [[planetary surface|planet's surface]]. Winds occur on a range of scales, from [[thunderstorm]] flows lasting tens of minutes, to local breezes generated by heating of [[land]] surfaces and lasting a few hours, to global winds resulting from the difference in [[absorption (electromagnetic radiation)|absorption]] of [[solar energy]] between the [[climate zone]]s on [[Earth]]. The study of wind is called '''anemology'''.<ref>"Anemology." Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/anemology. Accessed 23 Nov. 2024.</ref>
The two main causes of large-scale [[atmospheric circulation]] are the differential heating between the equator and the poles, and the rotation of the planet ([[Coriolis effect]]). Within the tropics and subtropics, [[thermal low]] circulations over terrain and high plateaus can drive [[monsoon]] circulations. In coastal areas the [[sea breeze]]/land breeze cycle can define local winds; in areas that have variable terrain, mountain and valley breezes can prevail.
Winds are commonly classified by their [[scale (spatial)|spatial scale]], their [[speed]] and direction, the forces that cause them, the regions in which they occur, and their effect. Winds have various defining aspects such as [[velocity]] ([[wind speed]]), the density of the gases involved, and energy content or [[wind energy]]. In [[meteorology]], winds are often referred to according to their strength, and the direction from which the wind is blowing. The convention for directions refer to where the wind comes from; therefore, a 'western' or 'westerly' wind blows from the west to the east, a 'northern' wind blows south, and so on. This is sometimes counter-intuitive.
Short bursts of high speed wind are termed [[Wind gust|gusts]]. Strong winds of intermediate duration (around one minute) are termed [[squall]]s. Long-duration winds have various names associated with their average strength, such as [[Wiktionary:breeze|breeze]], [[gale]], [[Storm#Classification|storm]], and [[hurricane]].
In [[outer space]], [[solar wind]] is the movement of gases or charged particles from the [[Sun]] through space, while [[planetary wind]] is the [[outgassing]] of light [[chemical element]]s from a planet's atmosphere into space. The strongest observed winds on a planet in the [[Solar System]] occur on [[Neptune]] and [[Saturn]].
In human civilization, the concept of wind has been explored in [[mythology]], influenced the events of history, expanded the range of transport and warfare, and provided a [[wind power|power source]] for mechanical work, electricity, and recreation. Wind powers the voyages of [[sailing ship]]s across Earth's oceans. [[Hot air balloon]]s use the wind to take short trips, and powered flight uses it to increase lift and reduce fuel consumption. Areas of [[wind shear]] caused by various weather phenomena can lead to dangerous situations for aircraft. When winds become strong, trees and human-made structures can be damaged or destroyed.
Winds can shape landforms, via a variety of [[aeolian processes]] such as the formation of fertile soils, for example [[loess]], and by [[erosion]]. Dust from large deserts can be moved great distances from its source region by the [[prevailing winds]]; winds that are accelerated by rough topography and associated with dust outbreaks have been assigned regional names in various parts of the world because of their significant effects on those regions. Wind also affects the spread of wildfires. Winds can disperse seeds from various plants, enabling the survival and dispersal of those plant species, as well as flying insect and bird populations. When combined with cold temperatures, the wind has a negative impact on livestock. Wind affects animals' food stores, as well as their hunting and defensive strategies.
== Causes ==
{{See also|Atmospheric pressure}}
[[File:10 PM March 12 surface analysis of Great Blizzard of 1888.png|thumb|right|[[surface weather analysis|Surface analysis]] of the [[Great Blizzard of 1888]]. Areas with greater isobaric packing indicate higher winds.]]
Wind is caused by differences in atmospheric pressure, which are primarily due to temperature differences. When a [[pressure gradient force|difference in atmospheric pressure]] exists, air moves from the higher to the lower pressure area, resulting in winds of various speeds. On a rotating planet, air will also be deflected by the [[Coriolis effect]], except exactly on the equator. Globally, the two major driving factors of large-scale wind patterns (the [[atmospheric circulation]]) are the differential heating between the equator and the poles (difference in absorption of [[solar energy]] leading to [[buoyancy force]]s) and the [[Coriolis effect|rotation of the planet]]. Outside the tropics and aloft from frictional effects of the surface, the large-scale winds tend to approach [[geostrophic balance]]. Near the Earth's surface, [[friction]] causes the wind to be slower than it would be otherwise. Surface friction also causes winds to blow more inward into low-pressure areas.<ref>{{cite web|author = JetStream|title = Origin of Wind|publisher = [[National Weather Service]] Southern Region Headquarters|year = 2008|access-date = 2009-02-16|url = http://www.srh.noaa.gov/jetstream//synoptic/wind.htm|archive-date = 2009-03-24|archive-url = https://web.archive.org/web/20090324043730/http://www.srh.noaa.gov/jetstream/synoptic/wind.htm|url-status = dead}}</ref><ref>{{cite journal|last=Makarieva|first=Anastassia|author2=V. G. Gorshkov, D. Sheil, A. D. Nobre, B.-L. Li|title=Where do winds come from? A new theory on how water vapor condensation influences atmospheric pressure and dynamics|journal=Atmospheric Chemistry and Physics|date=February 2013 |volume=13|issue=2|pages=1039–1056|doi=10.5194/acp-13-1039-2013|url=http://www.atmos-chem-phys.net/13/1039/2013/acp-13-1039-2013.html|access-date=2013-02-01|bibcode = 2013ACP....13.1039M|arxiv=1004.0355 |doi-access=free }}</ref>
Winds defined by an equilibrium of physical forces are used in the decomposition and analysis of wind profiles. They are useful for simplifying the atmospheric [[equations of motion]] and for making qualitative arguments about the horizontal and vertical distribution of horizontal winds. The [[geostrophic wind]] component is the result of the balance between Coriolis force and pressure gradient force. It flows parallel to [[isobar (meteorology)|isobars]] and approximates the flow above the [[atmospheric boundary layer]] in the midlatitudes.<ref>{{cite web|author=Glossary of Meteorology|title=Geostrophic wind|publisher=[[American Meteorological Society]]|year=2009|access-date=2009-03-18|url=http://amsglossary.allenpress.com/glossary/search?id=geostrophic-wind1|url-status=dead|archive-url=https://web.archive.org/web/20071016223621/http://amsglossary.allenpress.com/glossary/search?id=geostrophic-wind1|archive-date=2007-10-16}}</ref> The [[thermal wind]] is the ''difference'' in the geostrophic wind between two levels in the atmosphere. It exists only in an atmosphere with horizontal [[temperature gradient]]s.<ref>{{cite web|author=Glossary of Meteorology|year=2009|url=http://amsglossary.allenpress.com/glossary/search?p=1&query=thermal+wind&submit=Search|title=Thermal wind|publisher=American Meteorological Society|access-date=2009-03-18|url-status=dead|archive-url=https://web.archive.org/web/20110717205424/http://amsglossary.allenpress.com/glossary/search?p=1&query=thermal+wind&submit=Search|archive-date=2011-07-17}}</ref> The [[ageostrophy|ageostrophic wind]] component is the difference between actual and geostrophic wind, which is responsible for air "filling up" cyclones over time.<ref>{{cite web|author=Glossary of Meteorology|year=2009|url=http://amsglossary.allenpress.com/glossary/search?p=1&query=geostrophic+wind&submit=Search|title=Ageostrophic wind|publisher=American Meteorological Society|access-date=2009-03-18|url-status=dead|archive-url=https://web.archive.org/web/20110917044828/http://amsglossary.allenpress.com/glossary/search?p=1&query=geostrophic+wind&submit=Search|archive-date=2011-09-17}}</ref> The [[gradient wind]] is similar to the geostrophic wind but also includes [[centrifugal force]] (or [[centripetal acceleration]]).<ref>{{cite web|author=Glossary of Meteorology|year=2009|url=http://amsglossary.allenpress.com/glossary/search?id=gradient-wind1|title=Gradient wind|publisher=American Meteorological Society|access-date=2009-03-18|url-status=dead|archive-url=https://web.archive.org/web/20080528193203/http://amsglossary.allenpress.com/glossary/search?id=gradient-wind1|archive-date=2008-05-28}}</ref>
== Measurement ==
[[File:Anemometer 2745.JPG|right|thumb|Cup-type [[anemometer]] on a remote meteorological station]]
[[Wind direction]] is usually expressed in terms of the direction from which it originates. For example, a ''northerly'' wind blows from the north to the south.<ref name="HOWTOREAD">{{cite web|author=JetStream|year=2008|url=http://www.srh.weather.gov/srh/jetstream/synoptic/wxmaps.htm|title=How to read weather maps|publisher=National Weather Service|access-date=2009-05-16|url-status=dead|archive-url=https://web.archive.org/web/20120705003624/http://www.srh.weather.gov/srh/jetstream/synoptic/wxmaps.htm|archive-date=2012-07-05}}</ref> [[Weather vane]]s pivot to indicate the direction of the wind.<ref>{{cite web|author=Glossary of Meteorology|year=2009|url=http://amsglossary.allenpress.com/glossary//search?id=wind-vane1|title=Wind vane|publisher=American Meteorological Society|access-date=2009-03-17|url-status=dead|archive-url=https://web.archive.org/web/20071018042250/http://amsglossary.allenpress.com/glossary/search?id=wind-vane1|archive-date=2007-10-18}}</ref> At airports, [[windsock]]s indicate wind direction, and can also be used to estimate wind speed by the angle of hang.<ref>{{cite web|author=Glossary of Meteorology|year=2009|url=http://amsglossary.allenpress.com/glossary/search?p=1&query=wind+sock&submit=Search|title=Wind sock|publisher=American Meteorological Society|access-date=2009-03-17|url-status=dead|archive-url=https://web.archive.org/web/20120514033301/http://amsglossary.allenpress.com/glossary/search?p=1&query=wind+sock&submit=Search|archive-date=2012-05-14}}</ref> Wind speed is measured by [[anemometer]]s, most commonly using rotating cups or propellers. When a high measurement frequency is needed (such as in research applications), wind can be measured by the propagation speed of [[ultrasound]] signals or by the effect of ventilation on the resistance of a heated wire.<ref>{{cite web|author=Glossary of Meteorology|year=2009|url=http://amsglossary.allenpress.com/glossary/search?p=1&query=anemometer&submit=Search|title=Anemometer|publisher=American Meteorological Society|access-date=2009-03-17|url-status=dead|archive-url=https://web.archive.org/web/20110606085028/http://amsglossary.allenpress.com/glossary/search?p=1&query=anemometer&submit=Search|archive-date=2011-06-06}}</ref> Another type of anemometer uses [[pitot tube]]s that take advantage of the pressure differential between an inner tube and an outer tube that is exposed to the wind to determine the dynamic pressure, which is then used to compute the wind speed.<ref>{{cite web|author=Glossary of Meteorology|year=2009|url=http://amsglossary.allenpress.com/glossary/search?p=1&query=pitot+tube&submit=Search|title=Pitot tube|publisher=American Meteorological Society|access-date=2009-03-17|url-status=dead|archive-url=https://web.archive.org/web/20120514033528/http://amsglossary.allenpress.com/glossary/search?p=1&query=pitot+tube&submit=Search|archive-date=2012-05-14}}</ref>
Sustained wind speeds are reported globally at a {{convert|sp=us|10|m|adj=on}} height and are averaged over a 10‑minute time frame. The United States reports winds over a 1‑minute average for tropical cyclones,<ref name="NWSM Defs">{{cite web|author=Tropical Cyclone Weather Services Program|title=Tropical cyclone definitions|url=http://www.weather.gov/directives/sym/pd01006004curr.pdf|date=2006-06-01|access-date=2006-11-30|publisher=National Weather Service}}</ref> and a 2‑minute average within weather observations.<ref name="fmh1">Office of the Federal Coordinator for Meteorology. [http://www.ofcm.gov/publications/fmh/FMH1/FMH1.pdf Federal Meteorological Handbook No. 1 – Surface Weather Observations and Reports September 2005] Appendix A: Glossary. Retrieved 2008-04-06.</ref> India typically reports winds over a 3‑minute average.<ref>{{cite book|author1=Sharad K. Jain |author2=Pushpendra K. Agarwal |author3=Vijay P. Singh |year=2007|url=https://books.google.com/books?id=ZKs1gBhJSWIC&pg=RA1-PA187|title=Hydrology and Water Resources of India|publisher=Springer|page=187|access-date=2009-04-22|isbn=978-1-4020-5179-1}}</ref> Knowing the wind sampling average is important, as the value of a one-minute sustained wind is typically 14% greater than a ten-minute sustained wind.<ref>{{cite web|author=Jan-Hwa Chu|year=1999|url=http://www.nrlmry.navy.mil/~chu/chap6/se200.htm|title=Section 2. Intensity Observation and Forecast Errors|publisher=[[United States Navy]]|access-date=2008-07-04|archive-date=2012-08-30|archive-url=https://web.archive.org/web/20120830042306/http://www.nrlmry.navy.mil/~chu/chap6/se200.htm|url-status=dead}}</ref> A short burst of high speed wind is termed a [[wind gust]]; one technical definition of a wind gust is: the maxima that exceed the lowest wind speed measured during a ten-minute time interval by {{convert|sp=us|10|kn|km/h mph}} for periods of seconds. A [[squall]] is an increase of the wind speed above a certain threshold, which lasts for a minute or more.
To determine winds aloft, [[radiosondes]] determine wind speed by [[GPS]], [[LORAN|radio navigation]], or [[radar]] tracking of the probe.<ref>{{cite web|author=Glossary of Meteorology|year=2009|url=http://amsglossary.allenpress.com/glossary/search?p=1&query=rawinsonde&submit=Search|title=Rawinsonde|publisher=American Meteorological Society|access-date=2009-03-17|url-status=dead|archive-url=https://web.archive.org/web/20110606085122/http://amsglossary.allenpress.com/glossary/search?p=1&query=rawinsonde&submit=Search|archive-date=2011-06-06}}</ref> Alternatively, movement of the parent [[weather balloon]] position can be tracked from the ground visually using [[theodolite]]s.<ref>{{cite web|author=Glossary of Meteorology|year=2009|url=http://amsglossary.allenpress.com/glossary/search?id=pilot-balloon-observation1|title=Pibal|publisher=American Meteorological Society|access-date=2009-03-17|url-status=dead|archive-url=https://web.archive.org/web/20071110142820/http://amsglossary.allenpress.com/glossary/search?id=pilot-balloon-observation1|archive-date=2007-11-10}}</ref> [[Remote sensing]] techniques for wind include [[SODAR]], [[Doppler effect|Doppler]] [[lidar]]s and radars, which can measure the [[Doppler shift]] of [[electromagnetic radiation]] scattered or reflected off suspended [[aerosol]]s or [[molecule]]s, and [[radiometer]]s and radars can be used to measure the surface roughness of the ocean from space or airplanes. Ocean roughness can be used to estimate wind velocity close to the sea surface over oceans. Geostationary satellite imagery can be used to estimate the winds at cloud top based upon how far clouds move from one image to the next. [[Wind engineering]] describes the study of the effects of the wind on the built environment, including buildings, bridges and other artificial objects.
== Models ==
Models can provide spatial and temporal information about airflow. Spatial information can be obtained through the interpolation of data from various measurement stations, allowing for horizontal data calculation. Alternatively, profiles, such as the [[Log wind profile|logarithmic wind profile]], can be utilized to derive vertical information.
Temporal information is typically computed by solving the [[Navier–Stokes equations|Navier-Stokes equations]] within [[numerical weather prediction]] models, generating global data for [[General circulation model|General Circulation Models]] or specific regional data. The calculation of wind fields is influenced by factors such as [[radiation]] differentials, Earth's rotation, and friction, among others.<ref>{{Cite journal |last=Lorenc |first=A. C. |date=1986 |title=Analysis methods for numerical weather prediction |url=http://dx.doi.org/10.1002/qj.49711247414 |journal=Quarterly Journal of the Royal Meteorological Society |volume=112 |issue=474 |pages=1177–1194 |doi=10.1002/qj.49711247414 |bibcode=1986QJRMS.112.1177L |issn=0035-9009}}</ref> Solving the Navier-Stokes equations is a time-consuming numerical process, but [[machine learning]] techniques can help expedite computation time.<ref>{{Cite journal |last1=BenMoshe |first1=Nir |last2=Fattal |first2=Eyal |last3=Leitl |first3=Bernd |last4=Arav |first4=Yehuda |date=2023-06-07 |title=Using Machine Learning to Predict Wind Flow in Urban Areas |journal=Atmosphere |volume=14 |issue=6 |pages=990 |doi=10.3390/atmos14060990 |bibcode=2023Atmos..14..990B |issn=2073-4433|doi-access=free }}</ref>
Numerical weather prediction models have significantly advanced our understanding of atmospheric dynamics and have become indispensable tools in weather forecasting and [[climate]] research. By leveraging both spatial and temporal data, these models enable scientists to analyze and predict global and regional wind patterns, contributing to our comprehension of the Earth's complex atmospheric system.
== Wind force scale ==
{{See also|Tropical cyclone scales|Surface weather analysis}}Historically, the [[Beaufort scale|Beaufort wind force scale]], created by [[Francis Beaufort]], provides an empirical description of wind speed based on observed sea conditions. Originally it was a 13-level scale (0{{ndash}}12), but during the 1940s, the scale was expanded to 18 levels (0{{ndash}}17).<ref name="Beaufort">{{cite book|author=Walter J. Saucier|year=2003|url=https://books.google.com/books?id=CM99-uKpR00C&pg=PA407|title=Principles of Meteorological Analysis|publisher=[[Courier Dover Publications]]|isbn=978-0-486-49541-5|access-date=2009-01-09}}</ref> There are general terms that differentiate winds of different average speeds such as a breeze, a gale, a storm, or a hurricane. Within the Beaufort scale, gale-force winds lie between {{convert|sp=us|28|kn|km/h}} and {{convert|sp=us|55|kn|km/h}} with preceding adjectives such as moderate, fresh, strong, and whole used to differentiate the wind's strength within the gale category.<ref>{{cite web|author=Glossary of Meteorology|year=2009|url=http://amsglossary.allenpress.com/glossary/browse?s=G&p=1|title=G|publisher=American Meteorological Society|access-date=2009-03-18|url-status=dead|archive-url=https://web.archive.org/web/20121005143157/http://amsglossary.allenpress.com/glossary/browse?s=G&p=1|archive-date=2012-10-05}}</ref> A storm has winds of {{convert|sp=us|56|kn|km/h}} to {{convert|sp=us|63|kn|km/h}}.<ref>{{cite web|author=Glossary of Meteorology|year=2009|url=http://amsglossary.allenpress.com/glossary/search?id=storm1|title=Storm|publisher=American Meteorological Society|access-date=2009-03-18|url-status=dead|archive-url=https://web.archive.org/web/20071015220345/http://amsglossary.allenpress.com/glossary/search?id=storm1|archive-date=2007-10-15}}</ref> The terminology for tropical cyclones differs from one region to another globally. Most ocean basins use the average wind speed to determine the tropical cyclone's category. Below is a summary of the classifications used by [[Regional Specialized Meteorological Centre|Regional Specialized Meteorological Centers]] worldwide:
{| class="collapsible wikitable" border="1"
|-
! colspan=3 style="background: #ccf;"|General wind classifications
! colspan=7 style="background: #ccf;"|Tropical cyclone classifications (all winds are 10-minute averages)
|-
! rowspan="2"|[[Beaufort scale]]<ref name="Beaufort" />
! colspan="2"|10-minute sustained winds
! rowspan="2"|General term<ref>{{cite web|author=Coastguard Southern Region|year=2009|url=http://www.coastguardsouth.org.nz/the-beaufort-wind-scale-xidc26479.html|archive-url=https://web.archive.org/web/20081118065856/http://www.coastguardsouth.org.nz/the-beaufort-wind-scale-xidc26479.html|archive-date=2008-11-18|title=The Beaufort Wind Scale|access-date=2009-03-18}}</ref>
! rowspan="2"|N Indian Ocean<br />[[Indian Meteorological Department|IMD]]
! rowspan="2"|SW Indian Ocean<br />[[Météo-France|MF]]
!rowspan="2"| Australian region<br />South Pacific<br /> [[Bureau of Meteorology (Australia)|BoM]], [[Indonesian Agency for Meteorology, Climatology and Geophysics|BMKG]], [[Fiji Meteorological Service|FMS]], [[Meteorological Service of New Zealand Limited|MSNZ]]
! rowspan="2"|NW Pacific<br />[[Japan Meteorological Agency|JMA]]
!rowspan="2"| NW Pacific<br />[[Joint Typhoon Warning Center|JTWC]]
! rowspan="2"|NE Pacific &<br />N Atlantic<br />[[National Hurricane Center|NHC]] & [[Central Pacific Hurricane Center|CPHC]]
|-
! ([[knot (unit)|knots]])
!([[Kilometres per hour|km/h]])
|-
| 0
| <1
| <2
| Calm
|rowspan=5| Low Pressure Area
|rowspan=7| Tropical disturbance
|rowspan="9"| Tropical low<br />Tropical Depression
|rowspan="9"| Tropical depression
|rowspan="9"| Tropical depression
|rowspan="9"| Tropical depression
|-
| 1
| 1–3
| 2–6
| Light air
|-
| 2
| 4–6
| 7–11
| Light breeze
|-
| 3
| 7–10
| 13–19
| Gentle breeze
|-
| 4
| 11–16
| 20–30
| Moderate breeze
|-
| 5
| 17–21
| 31–39
| Fresh breeze
| rowspan=2| Depression
|-
| 6
| 22–27
| 41–50
| Strong breeze
|-
|rowspan=2| 7
| 28–29
| 52–54
|rowspan=2| Moderate gale
|rowspan=2| Deep depression
|rowspan=2| Tropical depression
|-
| 30–33
| 56–61
|-
| 8
| 34–40
| 63–74
| Fresh gale
|rowspan=2| Cyclonic storm
|rowspan=2| Moderate tropical storm
|rowspan=2| Tropical cyclone (1)
|rowspan=2| Tropical storm
|rowspan=4| Tropical storm
|rowspan=4| Tropical storm
|-
| 9
| 41–47
| 76–87
| Strong gale
|-
| 10
| 48–55
| 89–102
| Whole gale
|rowspan=2| Severe cyclonic storm
|rowspan=2| Severe tropical storm
|rowspan=2| Tropical cyclone (2)
|rowspan=2| Severe tropical storm
|-
| 11
| 56–63
| 104–117
| Storm
|-
|| 12
| 64–72
| 119–133
|rowspan=8| Hurricane
|rowspan=7| Very severe cyclonic storm
|rowspan=3| Tropical cyclone
|rowspan=2| Severe tropical cyclone (3)
|rowspan=8| Typhoon
|rowspan=6| Typhoon
|| Hurricane (1)
|-
||13
| 73–85
| 135–157
| Hurricane (2)
|-
||14
| 86–89
| 159–165
|rowspan=3| Severe tropical cyclone (4)
|rowspan=2| Major hurricane (3)
|-
||15
| 90–99
| 167–183
|rowspan=3| Intense tropical cyclone
|-
||16
| 100–106
| 185–196
|rowspan=3| Major hurricane (4)
|-
| rowspan=3|17
| 107–114
| 198–211
|rowspan=3| Severe tropical cyclone (5)
|-
| 115–119
| 213–220
|rowspan=2| Very intense tropical cyclone
|rowspan=2| Super typhoon
|-
| >120
| >222
| Super cyclonic storm
| Major hurricane (5)
|}
=== Enhanced Fujita scale ===
The [[Enhanced Fujita Scale]] (EF Scale) rates the strength of tornadoes by using damage to estimate wind speed. It has six levels, from visible damage to complete destruction. It is used in the United States and in some other countries, including Canada and France, with small modifications.<ref>{{Cite web|date=7 November 2013|title=Enhanced Fujita Scale|url=https://glossary.ametsoc.org/wiki/Enhanced_Fujita_Scale|access-date=21 June 2021|website=American Meteorological Society - Glossary of Meteorology}}</ref>
=== Station model ===
[[File:Wind barbs.gif|thumb|right|Wind plotting within a station model]]
The [[station model]] plotted on surface [[weather map]]s uses a wind barb to show both wind direction and speed. The wind barb shows the speed using "flags" on the end.
* Each half of a flag depicts {{convert|sp=us|5|kn|km/h mph}} of wind.
* Each full flag depicts {{convert|sp=us|10|kn|km/h mph}} of wind.
* Each [[pennant (commissioning)|pennant]] (filled triangle) depicts {{convert|sp=us|50|kn|km/h mph}} of wind.<ref>{{cite web|work=[[Hydrometeorological Prediction Center]]|year=2009|url=http://www.wpc.ncep.noaa.gov/html/stationplot.shtml|title=Decoding the station model|publisher=[[National Centers for Environmental Prediction]]|access-date=2007-05-16}}</ref>
Winds are depicted as blowing from the direction the barb is facing. Therefore, a northeast wind will be depicted with a line extending from the cloud circle to the northeast, with flags indicating wind speed on the northeast end of this line.<ref name=autogenerated1>{{cite web|url=http://www.srh.weather.gov/srh/jetstream/synoptic/wxmaps.htm|title=How to read weather maps|year=2008|work=JetStream|publisher=National Weather Service|access-date=2009-06-27|url-status=dead|archive-url=https://web.archive.org/web/20120705003624/http://www.srh.weather.gov/srh/jetstream/synoptic/wxmaps.htm|archive-date=2012-07-05}}</ref> Once plotted on a map, an analysis of [[isotach]]s (lines of equal wind speeds) can be accomplished. Isotachs are particularly useful in diagnosing the ___location of the [[jet stream]] on upper-level constant pressure charts, and are usually located at or above the 300 hPa level.<ref>{{cite book|author=Terry T. Lankford|year=2000|url=https://books.google.com/books?id=kSSn7vPgmUQC&pg=PT187|title=Aviation Weather Handbook|publisher=[[McGraw-Hill Professional]]|isbn=978-0-07-136103-3|access-date=2008-01-22}}</ref>
== Global climatology ==
{{Main|Prevailing winds}}
[[File:Map prevailing winds on earth.png|upright=1.5|thumb|The westerlies and trade winds]]
[[File:Earth Global Circulation.jpg|upright=1.5|thumb|Winds are part of Earth's atmospheric circulation]]
Easterly winds, on average, dominate the flow pattern across the poles, westerly winds blow across the [[mid-latitudes]] of the Earth, polewards of the [[subtropical ridge]], while easterlies again dominate the [[tropics]].
Directly under the subtropical ridge are the doldrums, or [[horse latitudes]], where winds are lighter. Many of the Earth's deserts lie near the average latitude of the subtropical ridge, where descent reduces the [[relative humidity]] of the air mass.<ref>{{cite book|url=https://books.google.com/books?id=g3CbqZtaF4oC&pg=PA121|title=Encyclopedia of Deserts|author=Michael A. Mares|page=121|access-date=2009-06-20|year=1999|publisher=University of Oklahoma Press|isbn=978-0-8061-3146-7}}</ref> The strongest winds are in the mid-latitudes where cold polar air meets warm air from the tropics.
=== Tropics ===
{{See also|Trade wind|Monsoon}}
The trade winds (also called trades) are the prevailing pattern of [[easterlies|easterly]] surface winds found in the tropics towards the Earth's [[equator]].<ref>{{cite web|title=trade winds|author=Glossary of Meteorology|publisher=American Meteorological Society|year=2000|access-date=2008-09-08|url=http://amsglossary.allenpress.com/glossary/search?id=trade-winds1|url-status=dead|archive-url=https://web.archive.org/web/20081211050708/http://amsglossary.allenpress.com/glossary/search?id=trade-winds1|archive-date=2008-12-11}}</ref> The trade winds blow predominantly from the northeast in the Northern Hemisphere and from the southeast in the Southern Hemisphere.<ref name="Ralph">{{cite book|author=[[Ralph Stockman Tarr]] and [[Frank Morton McMurry]]|year=1909|url=https://archive.org/details/advancedgeograp00commgoog|title=Advanced geography|publisher=W.W. Shannon, State Printing|page=[https://archive.org/details/advancedgeograp00commgoog/page/n310 246]|access-date=2009-04-15}}</ref> The trade winds act as the [[Tropical cyclone#Steering winds|steering flow]] for [[tropical cyclones]] that form over the world's oceans.<ref>{{cite web|author=[[Joint Typhoon Warning Center]]|year=2006|url=http://www.nrlmry.navy.mil/forecaster_handbooks/Philippines2/Forecasters%20Handbook%20for%20the%20Philippine%20Islands%20and%20Surrounding%20Waters%20Typhoon%20Forecasting.3.pdf|title=3.3 JTWC Forecasting Philosophies|publisher=United States Navy|access-date=2007-02-11|archive-date=2012-07-05|archive-url=https://web.archive.org/web/20120705161830/http://www.nrlmry.navy.mil/forecaster_handbooks/Philippines2/Forecasters%20Handbook%20for%20the%20Philippine%20Islands%20and%20Surrounding%20Waters%20Typhoon%20Forecasting.3.pdf|url-status=dead}}</ref> Trade winds also steer African dust westward across the Atlantic Ocean into the Caribbean, as well as portions of southeast North America.<ref name="pooraq">{{cite web|work=[[Science Daily]]|date=1999-07-14|url=https://www.sciencedaily.com/releases/1999/07/990714073433.htm|title=African Dust Called A Major Factor Affecting Southeast U.S. Air Quality|access-date=2007-06-10}}</ref>
A [[monsoon]] is a seasonal prevailing wind that lasts for several months within tropical regions. The term was first used in English in India, [[Bangladesh]], Pakistan, and neighboring countries to refer to the big seasonal winds blowing from the [[Indian Ocean]] and [[Arabian Sea]] in the southwest bringing heavy rainfall to the area.<ref>{{cite web|author=Glossary of Meteorology |year=2009 |publisher=American Meteorological Society |url=http://amsglossary.allenpress.com/glossary/search?p=1&query=monsoon&submit=Search |title=Monsoon |access-date=2008-03-14 |url-status=dead |archive-url=https://web.archive.org/web/20080322122025/http://amsglossary.allenpress.com/glossary/search?p=1&query=monsoon&submit=Search |archive-date=2008-03-22 }}</ref> Its poleward progression is accelerated by the development of a heat low over the Asian, African, and North American continents during May through July, and over Australia in December.<ref name="NCFMRF">{{cite web|url=http://www.ncmrwf.gov.in/Chapter-II.pdf |archive-url=https://web.archive.org/web/20110721161408/http://www.ncmrwf.gov.in/Chapter-II.pdf |archive-date=2011-07-21 |title=Chapter-II Monsoon-2004: Onset, Advancement and Circulation Features |access-date=2008-05-03 |date=2004-10-23 |publisher=National Centre for Medium Range Forecasting |url-status=dead }}</ref><ref>{{cite web|url=http://www.abc.net.au/storm/monsoon/print.htm|archive-url=https://web.archive.org/web/20010223103812/http://www.abc.net.au/storm/monsoon/print.htm|archive-date=2001-02-23|title=Monsoon|access-date=2008-05-03|publisher=Australian Broadcasting Corporation|year=2000}}</ref><ref>{{cite web|author= Alex DeCaria|url=http://snowball.millersville.edu/~adecaria/ESCI344/esci344_lesson04_seasonal_mean_wind_fields.pdf|title=Lesson 4 – Seasonal-mean Wind Fields|publisher=Millersville Meteorology|access-date=2008-05-03|date=2007-10-02}}</ref>
=== Westerlies and their impact ===
[[File:Franklingulfstream.jpg|thumb|[[Benjamin Franklin]]'s map of the [[Gulf Stream]]]]
{{Main|Westerlies}}
The Westerlies or the Prevailing Westerlies are the [[prevailing winds]] in the [[middle latitudes]] between 35 and 65 degrees [[latitude]]. These prevailing winds blow from the west to the east,<ref>{{cite web|author=Glossary of Meteorology|year=2009|url=http://amsglossary.allenpress.com/glossary/search?id=westerlies1|title=Westerlies|publisher=American Meteorological Society|access-date=2009-04-15|url-status=dead|archive-url=https://web.archive.org/web/20100622073904/http://amsglossary.allenpress.com/glossary/search?id=westerlies1|archive-date=2010-06-22}}</ref><ref>{{cite web|url=http://www.icbemp.gov/science/ferguson_42.pdf |title=Climatology of the Interior Columbia River Basin |author=Sue Ferguson |date=2001-09-07 |publisher=Interior Columbia Basin Ecosystem Management Project |access-date=2009-09-12 |url-status=dead |archive-url=https://web.archive.org/web/20090515003307/http://www.icbemp.gov/science/ferguson_42.pdf |archive-date=2009-05-15 }}</ref> and steer extratropical cyclones in this general manner. The winds are predominantly from the southwest in the Northern Hemisphere and from the northwest in the Southern Hemisphere.<ref name="Ralph" /> They are strongest in the winter when the pressure is lower over the poles, and weakest during the summer and when pressures are higher over the poles.<ref>{{cite web|author=Halldór Björnsson |year=2005 |url=http://andvari.vedur.is/~halldor/HB/Met210old/GlobCirc.html |title=Global circulation |publisher=Veðurstofu Íslands |access-date=2008-06-15 |url-status=dead |archive-url=https://web.archive.org/web/20110807132251/http://andvari.vedur.is/~halldor/HB/Met210old/GlobCirc.html |archive-date=2011-08-07 }}</ref>
Together with the [[trade wind]]s, the westerlies enabled a round-trip trade route for sailing ships crossing the Atlantic and Pacific Oceans, as the westerlies lead to the development of strong ocean currents on the western sides of oceans in both hemispheres through the process of [[western intensification]].<ref>{{cite web|author=[[National Environmental Satellite, Data, and Information Service]]|year=2009|url=http://www.science-house.org/nesdis/gulf/background.html|archive-url=https://web.archive.org/web/20100503013457/http://www.science-house.org/nesdis/gulf/background.html|archive-date=2010-05-03|title=Investigating the Gulf Stream|publisher=[[North Carolina State University]]|access-date=2009-05-06}}</ref> These western ocean currents transport warm, sub-tropical water polewards toward the [[polar region]]s. The westerlies can be particularly strong, especially in the southern hemisphere, where there is less land in the middle latitudes to cause the flow pattern to amplify, which slows the winds down. The strongest westerly winds in the middle latitudes are within a band known as the [[Roaring Forties]], between [[40th parallel south|40]] and [[50th parallel south|50 degrees latitude south]] of the equator.<ref>{{cite book|author=Stuart Walker|title=The sailor's wind|publisher=[[W. W. Norton & Company]]|year=1998|page=[https://archive.org/details/sailorswind00walk/page/91 91]|isbn=978-0-393-04555-0|url=https://archive.org/details/sailorswind00walk|url-access=registration|quote=Roaring Forties Shrieking Sixties westerlies.|access-date=2009-06-17}}</ref> The Westerlies play an important role in carrying the warm, equatorial waters and winds to the western coasts of continents,<ref name="DRIFT">{{cite web|author1=Barbie Bischof |author2=Arthur J. Mariano |author3=Edward H. Ryan |title=The North Atlantic Drift Current|year=2003|publisher=The [[National Oceanographic Partnership Program]]|access-date=2008-09-10|url=http://oceancurrents.rsmas.miami.edu/atlantic/north-atlantic-drift.html}}</ref><ref>{{cite book|author1=Erik A. Rasmussen |author2=John Turner |title=Polar Lows|year=2003|publisher=Cambridge University Press|page=68}}</ref> especially in the southern hemisphere because of its vast oceanic expanse.
=== Polar easterlies ===
{{Main|Polar easterlies}}
The polar easterlies, also known as Polar Hadley cells, are dry, cold prevailing winds that blow from the high-pressure areas of the [[polar high]]s at the [[North Pole|north]] and [[South Pole]]s towards the low-pressure areas within the Westerlies at high latitudes. Unlike the Westerlies, these prevailing winds blow from the east to the west, and are often weak and irregular.<ref>{{cite web|author=Glossary of Meteorology|year=2009|url=http://amsglossary.allenpress.com/glossary/search?p=1&query=polar+easterlies&submit=Search|title=Polar easterlies|publisher=American Meteorological Society|access-date=2009-04-15|url-status=dead|archive-url=https://web.archive.org/web/20120712094311/http://amsglossary.allenpress.com/glossary/search?p=1&query=polar+easterlies&submit=Search|archive-date=2012-07-12}}</ref> Because of the low sun angle, cold air builds up and [[Subsidence (atmosphere)|subsides]] at the pole creating surface high-pressure areas, forcing an equatorward outflow of air;<ref>{{cite web|author=Michael E. Ritter|year=2008|url=http://www.uwsp.edu/geO/faculty/ritter/geog101/textbook/circulation/global_scale_circulation.html|archive-url=https://web.archive.org/web/20090506102012/http://www.uwsp.edu/geO/faculty/ritter/geog101/textbook/circulation/global_scale_circulation.html|archive-date=2009-05-06|title=The Physical Environment: Global scale circulation|publisher=[[University of Wisconsin–Stevens Point]]|access-date=2009-04-15}}</ref> that outflow is deflected westward by the Coriolis effect.
== Local considerations ==
[[File:Map local winds.png|thumb|upright=1.75|Local winds around the world. These winds are formed through the heating of land (from mountains or flat terrain)]]
=== Sea and land breezes ===
{{Main|Sea breeze}}
[[File:Diagrama de formacion de la brisa-breeze.svg|thumb|A: Sea breeze (occurs at daytime), B: Land breeze (occurs at nighttime)]]
In coastal regions, sea breezes and land breezes can be important factors in a ___location's prevailing winds. The sea is warmed by the sun more slowly because of water's greater [[specific heat]] compared to land. As the temperature of the surface of the land rises, the land heats the air above it by conduction. The warm air is less dense than the surrounding environment and so it rises.<ref>{{cite web|author= Steve Ackerman|year=1995|url=http://cimss.ssec.wisc.edu/wxwise/seabrz.html|title=Sea and Land Breezes|publisher=University of Wisconsin|access-date=2006-10-24}}</ref> The cooler air above the sea, now with higher [[sea level pressure]], flows inland into the lower pressure, creating a cooler breeze near the coast. A background along-shore wind either strengthens or weakens the sea breeze, depending on its orientation with respect to the Coriolis force.<ref>{{Cite journal|last1=Steele|first1=C. J.|last2=Dorling|first2=S. R.|last3=Glasow|first3=R. von|last4=Bacon|first4=J.|date=2015|title=Modelling sea-breeze climatologies and interactions on coasts in the southern North Sea: implications for offshore wind energy|journal=Quarterly Journal of the Royal Meteorological Society|language=en|volume=141|issue=690|pages=1821–1835|doi=10.1002/qj.2484|bibcode=2015QJRMS.141.1821S |s2cid=119993890 |issn=1477-870X|doi-access=free}}</ref>
At night, the land cools off more quickly than the ocean because of differences in their specific heat values. This temperature change causes the daytime sea breeze to dissipate. When the temperature onshore cools below the temperature offshore, the pressure over the water will be lower than that of the land, establishing a land breeze, as long as an onshore wind is not strong enough to oppose it.<ref name="Jet">{{cite web|author=JetStream: An Online School For Weather |year=2008 |url=http://www.srh.weather.gov/srh/jetstream/ocean/seabreezes.htm |title=The Sea Breeze |publisher=National Weather Service |access-date=2006-10-24 |url-status=dead |archive-url=https://web.archive.org/web/20060923233344/http://www.srh.weather.gov/srh/jetstream/ocean/seabreezes.htm |archive-date=2006-09-23 }}</ref>
=== Near mountains ===
[[File:Vol d'onde.svg|right|thumb|Mountain wave schematic. The wind flows towards a mountain and produces a first oscillation (A). A second wave occurs further away and higher. The lenticular clouds form at the peak of the waves (B).]]
Over elevated surfaces, heating of the ground exceeds the heating of the surrounding air at the same altitude above [[sea level]], creating an associated thermal low over the terrain and enhancing any thermal lows that would have otherwise existed,<ref>{{cite web|author=National Weather Service Forecast Office in [[Tucson, Arizona]]|year=2008|url=http://www.wrh.noaa.gov/twc/monsoon/monsoon_whatis.php|title=What is a monsoon?|publisher=National Weather Service Western Region Headquarters|access-date=2009-03-08}}</ref><ref>{{cite journal|author=Douglas G. Hahn and [[Syukuro Manabe]]|year=1975|bibcode=1975JAtS...32.1515H|title=The Role of Mountains in the South Asian Monsoon Circulation|journal=[[Journal of the Atmospheric Sciences]]|volume=32|issue=8|pages=1515–1541|doi=10.1175/1520-0469(1975)032<1515:TROMIT>2.0.CO;2|doi-access=free}}</ref> and changing the wind circulation of the region. In areas where there is rugged [[topography]] that significantly interrupts the environmental wind flow, the wind circulation between mountains and valleys is the most important contributor to the prevailing winds. Hills and valleys substantially distort the airflow by increasing friction between the atmosphere and landmass by acting as a physical block to the flow, deflecting the wind parallel to the range just upstream of the topography, which is known as a [[barrier jet]]. This barrier jet can increase the low-level wind by 45%.<ref>{{cite journal|author=J. D. Doyle|year=1997|url=http://cat.inist.fr/?aModele=afficheN&cpsidt=2721180|title=The influence of mesoscale orography on a coastal jet and rainband|journal=[[Monthly Weather Review]]|volume=125|issue=7|pages=1465–1488|doi=10.1175/1520-0493(1997)125<1465:TIOMOO>2.0.CO;2|bibcode = 1997MWRv..125.1465D|doi-access=free}}</ref> Wind direction also changes because of the contour of the land.<ref name="Trex" />
If there is a [[mountain pass|pass]] in the mountain range, winds will rush through the pass with considerable speed because of the [[Bernoulli principle]] that describes an inverse relationship between speed and pressure. The airflow can remain turbulent and erratic for some distance downwind into the flatter countryside. These conditions are dangerous to ascending and descending [[airplane]]s.<ref name="Trex">{{cite web|author=National Center for Atmospheric Research |year=2006 |url=http://www.ucar.edu/communications/quarterly/spring06/trex.jsp |title=T-REX: Catching the Sierra's waves and rotors |publisher=University Corporation for Atmospheric Research |access-date=2006-10-21 |url-status=dead |archive-url=https://web.archive.org/web/20061121051137/http://www.ucar.edu/communications/quarterly/spring06/trex.jsp |archive-date=2006-11-21 }}</ref> Cool winds accelerating through mountain gaps have been given regional names. In Central America, examples include the [[Papagayo wind]], the [[Panama]] wind, and the [[Tehuano wind]]. In Europe, similar winds are known as the [[Bora (wind)|Bora]], [[Tramontane]], and [[Mistral (wind)|Mistral]]. When these winds blow over open waters, they increase mixing of the upper layers of the ocean that elevates cool, nutrient rich waters to the surface, which leads to increased marine life.<ref name="Papa">{{cite web|url=http://daac.gsfc.nasa.gov/oceancolor/scifocus/oceanColor/papagayo.shtml|title=The Papaguayo Wind|author=Anthony Drake|date=2008-02-08|publisher=[[NASA]] Goddard Earth Sciences Data and Information Services Center|access-date=2009-06-16|url-status=dead|archive-url=https://web.archive.org/web/20090614113851/http://daac.gsfc.nasa.gov/oceancolor/scifocus/oceanColor/papagayo.shtml|archive-date=2009-06-14}}</ref>
In mountainous areas, local distortion of the airflow becomes severe. Jagged terrain combines to produce unpredictable flow patterns and turbulence, such as [[lee waves|rotors]], which can be topped by [[lenticular cloud]]s. Strong [[updraft]]s, downdrafts, and [[eddies]] develop as the air flows over hills and down valleys. Orographic [[precipitation (meteorology)|precipitation]] occurs on the [[windward]] side of mountains and is caused by the rising air motion of a large-scale flow of moist air across the mountain ridge, also known as upslope flow, resulting in [[adiabatic lapse rate|adiabatic]] cooling and condensation. In mountainous parts of the world subjected to relatively consistent winds (for example, the trade winds), a more moist climate usually prevails on the windward side of a mountain than on the [[leeward]] or downwind side. Moisture is removed by orographic lift, leaving drier air on the descending and generally warming, leeward side where a [[rain shadow]] is observed.<ref name="MT">{{cite web|author=Michael Pidwirny |year=2008 |url=http://www.physicalgeography.net/fundamentals/8e.html |title=CHAPTER 8: Introduction to the Hydrosphere (e). Cloud Formation Processes |publisher=Physical Geography |access-date=2009-01-01 |url-status=dead |archive-url=https://web.archive.org/web/20081220230524/http://www.physicalgeography.net/fundamentals/8e.html |archive-date=2008-12-20 }}</ref>
Winds that flow over mountains down into lower elevations are known as downslope winds. These winds are warm and dry. In Europe downwind of the [[Alps]], they are known as [[foehn]]. In Poland, an example is the [[halny]] wiatr. In Argentina, the local name for down sloped winds is [[zonda (wind)|zonda]]. In Java, the local name for such winds is koembang. In New Zealand, they are known as the [[Nor'west arch]], and are accompanied by the cloud formation they are named after that has inspired artwork over the years.<ref>{{cite book|publisher=Auckland University Press|year=2003|access-date=2009-06-21|url=https://books.google.com/books?id=2Z3f8g18HPoC&pg=PA93|title=New Zealand Painting|author=Michael Dunn|isbn=978-1-86940-297-6|page=93}}</ref> In the Great Plains of the United States, these winds are known as a [[chinook wind|chinook]]. Downslope winds also occur in the foothills of the Appalachian mountains of the United States,<ref>{{cite journal|author=David M. Gaffin|title=Foehn Winds That Produced Large Temperature Differences near the Southern Appalachian Mountains|url=https://journals.ametsoc.org/waf/article/22/1/145/38793/Foehn-Winds-That-Produced-Large-Temperature|journal=Weather and Forecasting|date=2007|volume=22|issue=1|pages=145–159|doi=10.1175/WAF970.1|bibcode=2007WtFor..22..145G|citeseerx=10.1.1.549.7012|s2cid=120049170 }}</ref> and they can be as strong as other downslope winds<ref>{{cite journal|author=David M. Gaffin|title=On High Winds and Foehn Warming Associated with Mountain-Wave Events in the Western Foothills of the Southern Appalachian Mountains|journal=Weather and Forecasting|date=2009|volume=24|issue=1|pages=53–75|doi=10.1175/2008WAF2007096.1|bibcode=2009WtFor..24...53G|doi-access=free}}</ref> and unusual compared to other [[foehn winds]] in that the relative humidity typically changes little due to the increased moisture in the source air mass.<ref>{{cite journal|author=David M. Gaffin|title=Unexpected Warming Induced by Foehn Winds in the Lee of the Smoky Mountains|journal=Weather and Forecasting|volume=17|issue=4|pages=907–915|doi=10.1175/1520-0434(2002)017<0907:UWIBFW>2.0.CO;2|year=2002|bibcode=2002WtFor..17..907G|doi-access=free}}</ref> In California, downslope winds are funneled through mountain passes, which intensify their effect, and examples include the [[Santa Ana wind|Santa Ana]] and [[sundowner (wind)|sundowner]] winds. Wind speeds during downslope wind effect can exceed {{convert|sp=us|160|km/h|mph}}.<ref name="boulder">{{cite web|url=http://www.ucar.edu/communications/factsheets/winds.html|access-date=2009-06-16|date=2000-04-10|author=Rene Munoz|publisher=University Corporation for Atmospheric Research|title=Boulder's downslope winds|url-status=dead|archive-url=https://web.archive.org/web/20120319015922/http://www.ucar.edu/communications/factsheets/winds.html|archive-date=2012-03-19}}</ref>
== Shear ==
[[File:Hodographe NOAA.PNG|thumb|upright=1.25|[[Hodograph]] plot of wind vectors at various heights in the [[troposphere]], which is used to diagnose vertical [[wind shear]]]]
{{Main|Wind shear}}
Wind shear, sometimes referred to as [[wind gradient]], is a difference in wind speed and direction over a relatively short distance in the Earth's atmosphere.<ref>{{cite web|author=D. C. Beaudette|year=1988|url=http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/b3fb7dd636fb870b862569ba0068920b/$FILE/AC00-54.pdf|title=FAA Advisory Circular Pilot Wind Shear Guide via the Internet Wayback Machine|publisher=[[Federal Aviation Administration]]|access-date=2009-03-18|archive-date=2006-10-14|archive-url=https://web.archive.org/web/20061014025906/http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/b3fb7dd636fb870b862569ba0068920b/$FILE/AC00-54.pdf|url-status=dead}}</ref> Wind shear can be broken down into vertical and horizontal components, with horizontal wind shear seen across [[weather fronts]] and near the coast,<ref name="DR">{{cite web|author=David M. Roth|year=2006|url=http://www.wpc.ncep.noaa.gov/sfc/UASfcManualVersion1.pdf|title=Unified Surface Analysis Manual|publisher=[[Hydrometeorological Prediction Center]]|access-date=2006-10-22}}</ref> and vertical shear typically near the surface,<ref>{{cite web|author=Glossary of Meteorology|year=2007|url=http://amsglossary.allenpress.com/glossary/browse?s=e&p=14|title=E|publisher=American Meteorological Society|access-date=2007-06-03|url-status=dead|archive-url=https://web.archive.org/web/20120712091121/http://amsglossary.allenpress.com/glossary/browse?s=e&p=14|archive-date=2012-07-12}}</ref> though also at higher levels in the atmosphere near upper level jets and frontal zones aloft.<ref>{{cite web|publisher=BBC|year=2009|url=http://bbc.co.uk/weather/features/understanding/jetstreams_uk.shtml|archive-url=https://web.archive.org/web/20090214090842/http://bbc.co.uk/weather/features/understanding/jetstreams_uk.shtml|archive-date=2009-02-14|title=Jet Streams in the UK|access-date=2009-06-20}}</ref>
Wind shear itself is a [[microscale meteorology|microscale meteorological]] phenomenon occurring over a very small distance, but it can be associated with [[mesoscale meteorology|mesoscale]] or [[synoptic scale]] weather features such as [[squall line]]s and [[cold front]]s. It is commonly observed near [[microburst]]s and [[downburst]]s caused by [[thunderstorm]]s,<ref name="Cleghorn">{{cite web|author=Cheryl W. Cleghorn|year=2004|url=http://oea.larc.nasa.gov/PAIS/Windshear.html|title=Making the Skies Safer From Windshear|publisher=[[NASA]] [[Langley Air Force Base]]|access-date=2006-10-22|archive-url = https://web.archive.org/web/20060823125528/http://oea.larc.nasa.gov/PAIS/Windshear.html |archive-date = August 23, 2006|url-status=dead}}</ref> weather fronts, areas of locally higher low level winds referred to as low level jets, near mountains,<ref>{{cite web|author=[[National Center for Atmospheric Research]] |work=University Corporation for Atmospheric Research Quarterly |date=Spring 2006 |url=http://www.ucar.edu/communications/quarterly/spring06/trex.jsp |title=T-REX: Catching the Sierra's waves and rotors |access-date=2009-06-21 |url-status=dead |archive-url=https://web.archive.org/web/20090221180626/http://www.ucar.edu/communications/quarterly/spring06/trex.jsp |archive-date=2009-02-21 }}</ref> radiation inversions that occur because of clear skies and calm winds, buildings,<ref>{{cite book|author=Hans M. Soekkha|url=https://books.google.com/books?id=-siPJeF_nRYC&pg=PA229|title=Aviation Safety|isbn=978-90-6764-258-3|publisher=VSP|year=1997|page=229|access-date=2009-06-21}}</ref> [[wind turbine]]s,<ref>{{cite book|author=Robert Harrison|title=Large Wind Turbines|publisher=[[John Wiley & Sons]]|___location=[[Chichester]]|year=2001|isbn=978-0-471-49456-0|page=30}}</ref> and [[sailboat]]s.<ref>{{cite book|author=Ross Garrett|title=The Symmetry of Sailing|publisher=Sheridan House|___location=[[Dobbs Ferry]]|year=1996|pages=[https://archive.org/details/symmetryofsailin00garr/page/97 97–99]|isbn=978-1-57409-000-0|url=https://archive.org/details/symmetryofsailin00garr/page/97}}</ref> Wind shear has a significant effect on the control of aircraft during take-off and landing,<ref>{{cite web|title=Wind Shear|author=Gail S. Langevin|publisher=[[National Aeronautic and Space Administration]]|year=2009|url=http://oea.larc.nasa.gov/PAIS/Concept2Reality/wind_shear.html|access-date=2007-10-09|archive-url = https://web.archive.org/web/20071009144924/http://oea.larc.nasa.gov/PAIS/Concept2Reality/wind_shear.html |archive-date = October 9, 2007|url-status=dead}}</ref> and was a significant cause of aircraft accidents involving large loss of life within the United States.<ref name="Cleghorn" />
Sound movement through the atmosphere is affected by wind shear, which can bend the wave front, causing sounds to be heard where they normally would not, or vice versa.<ref>{{cite report|publisher=Washington State Department of Transportation|url=http://www.wsdot.wa.gov/Research/Reports/000/033.1.htm|title=Ground Plane Wind Shear Interaction on Acoustic Transmission|access-date=2007-05-30|version=WA-RD 033.1|author=Rene N. Foss|date=June 1978}}</ref> Strong vertical wind shear within the troposphere also inhibits [[tropical cyclone]] development,<ref>{{cite web|author=University of Illinois|year=1999|url=http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/hurr/grow/home.rxml|title=Hurricanes|access-date=2006-10-21}}</ref> but helps to organize individual thunderstorms into living longer life cycles that can then produce [[severe weather]].<ref>{{cite web|author=University of Illinois|year=1999|url=http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/svr/comp/wind/home.rxml|title=Vertical Wind Shear|access-date=2006-10-21|archive-date=2019-03-16|archive-url=https://web.archive.org/web/20190316191915/http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/svr/comp/wind/home.rxml|url-status=dead}}</ref> The [[thermal wind]] concept explains how differences in wind speed with height are dependent on horizontal temperature differences, and explains the existence of the [[jet stream]].<ref name="IP">{{cite web|url=http://www.tpub.com/weather3/6-15.htm|title=Unit 6—Lesson 1: Low-Level Wind Shear|access-date=2009-06-21|year=2007|author=Integrated Publishing}}</ref>
==In civilization==
=== Religion ===
As a natural force, the wind was often personified as one or more [[wind god]]s or as an expression of the [[supernatural]] in many cultures. [[Vayu]] is the [[Historical Vedic religion|Vedic]] and Hindu God of Wind.<ref>{{cite web|author=Laura Gibbs|date=2007-10-16|url=http://www.mythfolklore.net/india/encyclopedia/vayu.htm|title=Vayu|publisher=Encyclopedia for Epics of Ancient India|access-date=2009-04-09}}</ref><ref name="Jordan">{{cite book|author=Michael Jordan|title=Encyclopedia of Gods: Over 2, 500 Deities of the World|publisher=Facts on File|___location=New York|year=1993|pages=[https://archive.org/details/encyclopediaofgo00jord/page/5 5, 45, 80, 187–188, 243, 280, 295]|isbn=978-0-8160-2909-9|url=https://archive.org/details/encyclopediaofgo00jord/page/5}}</ref> The Greek wind gods include [[Boreas (god)|Boreas]], [[Greek Goddess|Notus]], [[Eurus]], and [[Zephyrus]].<ref name="Jordan" /> [[Aeolus]], in varying interpretations the ruler or keeper of the four winds, has also been described as [[Astraeus]], the god of dusk who fathered the four winds with [[Eos]], goddess of dawn. The [[ancient Greeks]] also observed the seasonal change of the winds, as evidenced by the [[Tower of the Winds]] in [[Athens]].<ref name="Jordan" /> Venti are the Roman gods of the winds.<ref>{{cite web|author=Theoi Greek Mythology|year=2008|url=http://www.theoi.com/Titan/Anemoi.html|title=Anemi: Greek Gods of the Winds|publisher=Aaron Atsma|access-date=2009-04-10}}</ref> [[Fūjin]] is the Japanese wind god and is one of the eldest [[Shinto]] gods. According to legend, he was present at the creation of the world and first let the winds out of his bag to clear the world of mist.<ref>{{cite book|author=John Boardman|title=The Diffusion of Classical Art in Antiquity|year = 1994|publisher = [[Princeton University Press]]|isbn=978-0-691-03680-9}}</ref> In [[Norse mythology]], [[Njörðr]] is the god of the wind.<ref name="Jordan" /> There are also four dvärgar ([[Norse dwarves]]), named [[Norðri, Suðri, Austri and Vestri]], and probably the [[four stags of Yggdrasil]], personify the four winds, and parallel the four Greek wind gods.<ref>{{cite book|author=Andy Orchard|year=1997|title=Dictionary of Norse Myth and Legend|publisher=[[Orion Publishing Group|Cassell]]|isbn=978-0-304-36385-8}}</ref> [[Stribog]] is the name of the [[Slavic Mythology|Slavic god]] of winds, sky and air. He is said to be the ancestor (grandfather) of the winds of the eight directions.<ref name="Jordan" />
==
[[Kamikaze (typhoon)|Kamikaze]] is a Japanese word, usually translated as divine wind, believed to be a gift from the gods. The term is first known to have been used as the name of a pair or series of typhoons that are said to have saved Japan from two Mongol fleets under Kublai Khan that attacked Japan in 1274 and again in 1281.<ref>{{cite web|author=History Detectives|year=2008|url=https://www.pbs.org/opb/historydetectives/investigations/405_kamikaze.html|archive-url=https://web.archive.org/web/20081025121023/http://www.pbs.org/opb/historydetectives/investigations/405_kamikaze.html|archive-date=2008-10-25|title=Feature – Kamikaze Attacks|publisher=[[PBS]]|access-date=2009-03-21}}</ref> [[Protestant Wind]] is a name for the storm that deterred the [[Spanish Armada]] from an invasion of England in 1588 where the wind played a pivotal role,<ref>{{cite book|url=https://books.google.com/books?id=O6-ba7yu2OcC&pg=PA229|title=The Spanish Armada|author1=Colin Martin |author2=Geoffrey Parker |access-date=2009-06-20|pages=144–181|publisher=Manchester University Press|year=1999|isbn=978-1-901341-14-0}}</ref> or the favorable winds that enabled [[William III of England|William of Orange]] to invade England in 1688.<ref>{{cite journal|author1=S. Lindgrén |author2=J. Neumann |name-list-style=amp |year=1985|doi=10.1175/1520-0477(1985)066<0634:GHETWS>2.0.CO;2|title=Great Historical Events That Were Significantly Affected by the Weather: 7, "Protestant Wind"—"Popish Wind": The Revolusion of 1688 in England|bibcode=1985BAMS...66..634L|volume= 66|issue= 6|journal=Bulletin of the American Meteorological Society|pages=634–644|doi-access=free}}</ref> During [[Napoleon]]'s [[French Invasion of Egypt (1798)|Egyptian Campaign]], the French soldiers had a hard time with the [[khamsin]] wind: when the storm appeared "as a blood-stint in the distant sky", the Ottomans went to take cover, while the French "did not react until it was too late, then choked and fainted in the blinding, suffocating walls of dust".<ref>{{cite book|author=Nina Burleigh|year=2007|title=Mirage|publisher=Harper|page=[https://archive.org/details/miragenapoleonss00burl/page/135 135]|isbn=978-0-06-059767-2|url=https://archive.org/details/miragenapoleonss00burl/page/135}}</ref> During the [[North African Campaign]] of the World War II, "allied and German troops were several times forced to halt in mid-battle because of sandstorms caused by khamsin... Grains of sand whirled by the wind blinded the soldiers and created electrical disturbances that rendered compasses useless."<ref>{{cite book|author=Jan DeBlieu|year=1998|title=Wind|publisher=Houghton Mifflin Harcourt|isbn=978-0-395-78033-6|page=[https://archive.org/details/windhowflowofai00debl/page/57 57]|url=https://archive.org/details/windhowflowofai00debl/page/57}}</ref>
=== Transportation ===
[[File:Exeter-20may44.jpg|thumb|[[Exeter International Airport|RAF Exeter]] airfield on 20 May 1944, showing the layout of the [[runway]]s that allow aircraft to take off and land into the wind]]
There are many different forms of sailing ships, but they all have certain basic things in common. Except for [[rotor ship]]s using the [[Magnus effect]], every sailing ship has a [[hull (ship)|hull]], [[rigging]] and at least one [[mast (sailing)|mast]] to hold up the [[sail]]s that use the wind to power the ship.<ref>{{cite book|author1=Ernest Edwin Speight |author2=Robert Morton Nance |name-list-style=amp |year=1906|url=https://archive.org/details/britainsseastor00nancgoog|quote=structure of sailing ship. |title=Britain's Sea Story, B.C. 55-A.D. 1805|publisher=[[Hodder and Stoughton]]|page=[https://archive.org/details/britainsseastor00nancgoog/page/n45 30]|access-date=2009-03-19}}</ref> Ocean journeys by sailing ship can take many months,<ref>{{cite news|author1=Brandon Griggs |author2=Jeff King |name-list-style=amp |date=2009-03-09|url=http://www.cnn.com/2009/TECH/03/09/plastic.bottle.boat/index.html|title=Boat made of plastic bottles to make ocean voyage|publisher=CNN|access-date=2009-03-19}}</ref> and a common hazard is becoming becalmed because of lack of wind,<ref>{{cite book|author=Jerry Cardwell|year=1997|url=https://archive.org/details/sailingbigonsmal00card|url-access=registration|title=Sailing Big on a Small Sailboat|publisher=Sheridan House, Inc|page=[https://archive.org/details/sailingbigonsmal00card/page/118 118]|isbn=978-1-57409-007-9|access-date=2009-03-19}}</ref> or being blown off course by severe [[storm]]s or winds that do not allow progress in the desired direction.<ref>{{cite book|author1=Brian Lavery |author2=Patrick O'Brian |name-list-style=amp |year=1989|url=https://books.google.com/books?id=uH--DfZKzE4C&pg=PA191|title=Nelson's navy|publisher=Naval Institute Press|page=191|access-date=2009-06-20|isbn=978-1-59114-611-7}}</ref> A severe storm could lead to [[shipwreck]], and the loss of all hands.<ref>{{cite web|author=Underwater Archaeology Kids' Corner|year=2009|url=http://www.wisconsinhistory.org/shipwrecks/kids/sse.asp|title=Shipwrecks, Shipwrecks Everywhere|publisher=[[Wisconsin Historical Society]]|access-date=2009-03-19|archive-date=2008-05-13|archive-url=https://web.archive.org/web/20080513074012/http://www.wisconsinhistory.org/shipwrecks/kids/sse.asp|url-status=dead}}</ref> Sailing ships can only carry a certain quantity of supplies in their [[hold (ship)|hold]], so they have to plan long [[Maritime history|voyages]] carefully to include appropriate [[Provisioning of USS Constitution|provisions]], including fresh water.<ref>{{cite book|author=Carla Rahn Phillips|year=1993|url=https://books.google.com/books?id=tVAxgY0sUpEC&pg=PA67|title=The Worlds of Christopher Columbus|publisher=Cambridge University Press|page=67|isbn=978-0-521-44652-5|access-date=2009-03-19}}</ref>
For [[aerodynamic]] aircraft which operate relative to the air, winds affect groundspeed,<ref>{{cite web|author=Tom Benson|year=2008|url=http://www.grc.nasa.gov/WWW/K-12/airplane/move2.html|title=Relative Velocities: Aircraft Reference|publisher=[[NASA]] [[Glenn Research Center]]|access-date=2009-03-19}}</ref> and in the case of lighter-than-air vehicles, wind may play a significant or solitary role in their movement and [[ground track]].<ref>{{cite web|author=[[Library of Congress]] |date=2006-01-06 |url=https://www.loc.gov/exhibits/treasures/wb-dream.html |title=The Dream of Flight |website=[[Library of Congress]] |access-date=2009-06-20 |url-status=dead |archive-url=https://web.archive.org/web/20090728044459/http://www.loc.gov/exhibits/treasures/wb-dream.html |archive-date=2009-07-28 }}</ref> The [[velocity]] of surface wind is generally the primary factor governing the direction of flight operations at an airport, and [[airfield]] runways are aligned to account for the common wind direction(s) of the local area. While taking off with a [[tailwind]] may be necessary under certain circumstances, a [[headwind]] is generally desirable. A tailwind increases takeoff distance required and decreases the climb gradient.<ref>{{cite web|publisher=[[Bristol International Airport]] |year=2004 |url=http://www.bristolairport.co.uk/upload/flight_paths.pdf |archive-url=https://wayback.archive-it.org/all/20090326133109/http://www.bristolairport.co.uk/upload/flight_paths.pdf |url-status=dead |archive-date=2009-03-26 |title=Flight Paths |access-date=2009-03-19 }}</ref>
=== Power source ===
[[File:Windenergy.jpg|thumb|right|This [[wind turbine]] generates electricity from wind power.]]
{{See also|Wind power|Wind atlas}}
The ancient [[Sinhalese people|Sinhalese]] of [[Anuradhapura]] and in other cities around [[Sri Lanka]] used the monsoon winds to power furnaces as early as 300 [[Common Era|BCE]]. The furnaces were constructed on the path of the monsoon winds to bring the temperatures inside up to {{convert|sp=us|1200|C|F}}.<ref>{{cite journal|author=G. Juleff|title=An ancient wind powered iron smelting technology in Sri Lanka|doi=10.1038/379060a0|bibcode=1996Natur.379...60J|journal=Nature|volume= 379|issue=3|pages=60–63|year= 1996|s2cid=205026185}}</ref> A rudimentary [[windmill]] was used to power an [[organ (music)|organ]] in the first century CE.<ref>{{cite journal |author=[[A. G. Drachmann]] |title=Heron's Windmill |journal=Centaurus |volume=7 |issue=2 |year=1961 |pages=145–151 |doi=10.1111/j.1600-0498.1960.tb00263.x |bibcode=1960Cent....7..145R }}</ref> Windmills were later built in [[Sistan]], [[Afghanistan]], from the 7th century CE. These were vertical-axle windmills,<ref>{{cite book|author=[[Ahmad Y Hassan]] and [[Donald Routledge Hill]]|year=1986|title=Islamic Technology: An illustrated history|page=[https://archive.org/details/islamictechnolog0000hasa/page/54 54]|publisher=Cambridge University Press|isbn=978-0-521-42239-0|url=https://archive.org/details/islamictechnolog0000hasa/page/54}}</ref> with [[Windmill sail|sails]] covered in [[reed mat (craft)|reed matting]] or cloth material. These windmills were used to grind corn and draw up water, and were used in the [[gristmill]]ing and sugarcane industries.<ref>{{cite journal|author=[[Donald Routledge Hill]]|title=Mechanical Engineering in the Medieval Near East|journal=Scientific American|date=May 1991|volume=264|issue=5|pages=64–69|doi=10.1038/scientificamerican0591-100|bibcode=1991SciAm.264e.100H}}</ref> Horizontal-axle windmills were later used extensively in Northwestern Europe to grind flour beginning in the 1180s, and many Dutch windmills still exist.
Wind power is now one of the main sources of [[renewable energy]], and its use is growing rapidly, driven by innovation and falling prices.<ref>{{Cite web|last=IRENA|title=Wind energy|url=https://www.irena.org/wind|access-date=2021-06-20|website=International Renewable Energy Agency|language=en}}</ref> Most of the installed capacity in wind power is [[Wind farm|onshore]], but [[offshore wind power]] offers a large potential as wind speeds are typically higher and more constant away from the coast.<ref>{{Cite book|last1=Kutscher|first1=Charles F.|url=https://www.worldcat.org/oclc/1082243945|title=Principles of Sustainable Energy Systems, Third Edition|last2=Milford|first2=Jana B.|last3=Kreith|first3=Frank|date=2019|publisher=Taylor & Francis Group|isbn=978-0-429-48558-9|edition=3rd|___location=Boca Raton, FL|pages=34|oclc=1082243945}}</ref> Wind energy the [[kinetic energy]] of the air, is proportional to the third power of wind velocity. [[Betz's law]] described the theoretical upper limit of what fraction of this energy wind turbines can extract, which is about 59%.<ref>[http://apps.carleton.edu/campus/library/digitalcommons/assets/pacp_7.pdf The Physics of Wind Turbines]. Kira Grogg Carleton College (2005) p. 8. (PDF). Retrieved 2011-11-03.</ref>
=== Recreation ===
[[File:Lilienthal in flight.jpg|thumb|right|[[Otto Lilienthal]] in flight]]
Wind figures prominently in several popular sports, including recreational [[hang gliding]], [[hot air ballooning]], [[kite]] flying, [[snowkiting]], [[kite landboarding]], [[kite surfing]], [[paragliding]], [[sailing]], and [[windsurfing]]. In gliding, wind gradients just above the surface affect the takeoff and landing phases of flight of a [[Glider aircraft|glider]]. Wind gradient can have a noticeable effect on [[ground launch]]es, also known as winch launches or wire launches. If the wind gradient is significant or sudden, or both, and the pilot maintains the same pitch attitude, the indicated airspeed will increase, possibly exceeding the maximum ground launch tow speed. The pilot must adjust the airspeed to deal with the effect of the gradient.<ref>{{cite book|title=Glider Flying Handbook|year=2003|publisher=U.S. Federal Aviation Administration|___location=U.S. Government Printing Office, Washington, D.C.|id=FAA-8083-13_GFH|pages=7–16|url=http://www.faa.gov/library/manuals/aircraft/glider_handbook/|archive-url=https://web.archive.org/web/20051218083721/http://www.faa.gov/library/manuals/aircraft/glider_handbook/|url-status=dead|archive-date=2005-12-18|access-date=2009-06-17}}</ref> When landing, wind shear is also a hazard, particularly when the winds are strong. As the glider descends through the wind gradient on final approach to landing, airspeed decreases while sink rate increases, and there is insufficient time to accelerate prior to ground contact. The pilot must anticipate the wind gradient and use a higher approach speed to compensate for it.<ref name=Piggott>{{cite book|author=Derek Piggott|title=Gliding: a Handbook on Soaring Flight|publisher=Knauff & Grove|year=1997|isbn=978-0-9605676-4-5|pages=85–86, 130–132}}</ref>
== In the natural world ==
{{See also|Aeolian processes}}
In arid climates, the main source of erosion is wind.<ref name="Erosion">{{cite web|author1=Vern Hofman |author2=Dave Franzen |name-list-style=amp |year=1997|url=http://www.ag.ndsu.edu/disaster/drought/emergencytillagetocontrolerosion.html|title=Emergency Tillage to Control Wind Erosion|publisher=[[North Dakota State University]] Extension Service|access-date=2009-03-21}}</ref> The general wind circulation moves small particulates such as dust across wide oceans thousands of kilometers downwind of their point of origin,<ref name="Gobi">{{cite journal|author1=James K. B. Bishop|author2=Russ E. Davis|author3=Jeffrey T. Sherman |year=2002 |url=http://flameglo.lbl.gov/people/bishop/bishoppubs/SOLOseesDust817.pdf |title=Robotic Observations of Dust Storm Enhancement of Carbon Biomass in the North Pacific |journal=Science |volume=298 |issue=5594 |pages=817–821 |access-date=2009-06-20 |doi=10.1126/science.1074961 |pmid=12399588 |bibcode=2002Sci...298..817B |s2cid=38762011 |url-status=dead |archive-url=https://web.archive.org/web/20100601154940/http://flameglo.lbl.gov/people/bishop/bishoppubs/SOLOseesDust817.pdf |archive-date=2010-06-01 }}</ref> which is known as deflation. Westerly winds in the mid-latitudes of the planet drive the movement of ocean currents from west to east across the world's oceans. Wind has a very important role in aiding plants and other immobile organisms in dispersal of seeds, spores, pollen, etc. Although wind is not the primary form of seed dispersal in plants, it provides dispersal for a large percentage of the biomass of land plants.
=== Erosion ===
[[File:Im Salar de Uyuni.jpg|thumb|right|A rock formation in the [[Altiplano]], [[Bolivia]], sculpted by wind erosion]]
Erosion can be the result of material movement by the wind. There are two main effects. First, wind causes small particles to be lifted and therefore moved to another region. This is called deflation. Second, these suspended particles may impact on solid objects causing erosion by abrasion (ecological succession). Wind erosion generally occurs in areas with little or no vegetation, often in areas where there is insufficient rainfall to support vegetation. An example is the formation of sand [[dunes]], on a beach or in a desert.<ref>{{cite web|author=[[United States Geological Survey]]|year=2004|url=http://geomaps.wr.usgs.gov/parks/coast/dunes/index.html|title=Dunes – Getting Started|access-date=2009-03-21|archive-url=https://web.archive.org/web/20090726013120/http://geomaps.wr.usgs.gov/parks/coast/dunes/index.html|archive-date=2009-07-26|url-status=dead}}</ref> Loess is a homogeneous, typically nonstratified, porous, [[friable]], slightly coherent, often calcareous, fine-grained, [[silt]]y, pale yellow or buff, windblown (Aeolian) [[sediment]].<ref>{{cite journal|author=F. von Richthofen|year=1882|title=On the mode of origin of the loess|journal=Geological Magazine (Decade II)|doi=10.1017/S001675680017164X |volume= 9|issue=7|pages=293–305|bibcode=1882GeoM....9..293R|s2cid=131245730 |url=https://zenodo.org/record/1880729}}</ref> It generally occurs as a widespread blanket deposit that covers areas of hundreds of square kilometers and tens of meters thick. Loess often stands in either steep or vertical faces.<ref>{{cite book|author1=K.E.K. Neuendorf |author2=J.P. Mehl, Jr. |author3=J.A. Jackson |name-list-style=amp |year=2005|title=Glossary of Geology|publisher=[[Springer-Verlag]], New York|page=779|isbn=978-3-540-27951-8}}</ref> Loess tends to develop into highly rich soils. Under appropriate climatic conditions, areas with loess are among the most agriculturally productive in the world.<ref>{{cite book|author=Arthur Getis|author2=Judith Getis and Jerome D. Fellmann|title=Introduction to Geography, Seventh Edition|year=2000|publisher=[[McGraw-Hill]]|isbn=978-0-697-38506-2|page=[https://archive.org/details/introductiontoge00geti/page/99 99]|url=https://archive.org/details/introductiontoge00geti/page/99}}</ref> Loess deposits are geologically unstable by nature, and will erode very readily. Therefore, [[windbreak]]s (such as big trees and bushes) are often planted by farmers to reduce the wind erosion of loess.<ref name="Erosion" />
=== Desert dust migration ===
During mid-summer (July in the northern hemisphere), the westward-moving trade winds south of the northward-moving subtropical ridge expand northwestward from the Caribbean into southeastern North America. When dust from the [[Sahara]] moving around the southern periphery of the ridge within the belt of trade winds moves over land, rainfall is suppressed and the sky changes from a blue to a white appearance, which leads to an increase in red sunsets. Its presence negatively impacts [[air quality]] by adding to the count of airborne particulates.<ref name=autogenerated2>{{cite web|author=Science Daily|date=1999-07-14|url=https://www.sciencedaily.com/releases/1999/07/990714073433.htm|title=African Dust Called A Major Factor Affecting Southeast U.S. Air Quality|access-date=2007-06-10}}</ref> Over 50% of the African dust that reaches the United States affects Florida.<ref>{{cite web|author=Science Daily|date=2001-06-15|url=https://www.sciencedaily.com/releases/2001/06/010615071508.htm|title=Microbes And The Dust They Ride In On Pose Potential Health Risks|access-date=2007-06-10}}</ref> Since 1970, dust outbreaks have worsened because of periods of drought in Africa. There is a large variability in the dust transport to the Caribbean and Florida from year to year.<ref>{{cite web|author=Usinfo.state.gov |year=2003 |url=http://www.gcrio.org/OnLnDoc/pdf/african_dust.pdf |title=Study Says African Dust Affects Climate in U.S., Caribbean |access-date=2007-06-10 |url-status=dead |archive-url=https://web.archive.org/web/20070620013708/http://www.gcrio.org/OnLnDoc/pdf/african_dust.pdf |archive-date=2007-06-20 }}</ref> Dust events have been linked to a decline in the health of [[coral reef]]s across the Caribbean and Florida, primarily since the 1970s.<ref>{{cite web|author=[[U. S. Geological Survey]]|year=2006|url=http://coastal.er.usgs.gov/african_dust/|title=Coral Mortality and African Dust|access-date=2007-06-10|archive-date=2012-05-02|archive-url=https://web.archive.org/web/20120502091350/http://coastal.er.usgs.gov/african_dust/|url-status=dead}}</ref> Similar dust plumes originate in the [[Gobi Desert]], which combined with pollutants, spread large distances downwind, or eastward, into North America.<ref name="Gobi" />
There are local names for winds associated with sand and dust storms. The [[Calima (Saharan sand)|Calima]] carries dust on southeast winds into the [[Canary islands]].<ref>{{cite web|url=http://www.weatheronline.co.uk/reports/wind/The-Calima.htm|author=Weather Online|year=2009|access-date=2009-06-17|title=Calima}}</ref> The [[Harmattan]] carries dust during the winter into the [[Gulf of Guinea]].<ref>{{cite journal |title=Harmattan dust deposition and particle size in Ghana |author1=Henrik Breuning-Madsen and Theodore W. Awadzi |year=2005 |journal=Catena |volume=63 |issue=1 |pages=23–38 |doi=10.1016/j.catena.2005.04.001|bibcode=2005Caten..63...23B }}</ref> The [[Sirocco]] brings dust from north Africa into southern Europe because of the movement of extratropical cyclones through the Mediterranean.<ref>{{cite web|url=http://www.weatheronline.co.uk/reports/wind/The-Sirocco.htm|author=Weather Online|year=2009 |access-date=2009-06-17 |title=Sirocco (Scirocco)}}</ref> Spring storm systems moving across the eastern Mediterranean Sea cause dust to carry across [[Egypt]] and the [[Arabian Peninsula]], which are locally known as [[Khamsin]].<ref>{{cite web|publisher=BBC|title=The Khamsin|url=http://www.bbc.co.uk/weather/features/understanding/khamsin.shtml|archive-url=https://web.archive.org/web/20090313013034/http://www.bbc.co.uk/weather/features/understanding/khamsin.shtml|archive-date=2009-03-13|author=Bill Giles (O.B.E)|year=2009|access-date=2009-06-17}}</ref> The [[Shamal (wind)|Shamal]] is caused by cold fronts lifting dust into the atmosphere for days at a time across the [[Persian Gulf]] states.<ref>{{cite web|author=Thomas J. Perrone|publisher=United States Navy|date=August 1979|url=http://www.nrlmry.navy.mil/forecaster_handbooks/WinterShamal/Toc.htm|title=Table of Contents: Wind Climatology of the Winter Shamal|access-date=2009-06-17|archive-date=2010-05-06|archive-url=https://web.archive.org/web/20100506154130/http://www.nrlmry.navy.mil/forecaster_handbooks/WinterShamal/Toc.htm|url-status=dead}}</ref>
=== Effect on plants ===
[[File:Salsola tragus tumbleweed.jpg|thumb|[[Tumbleweed]] blown against a fence]]
[[File:Coarse woody debris 6407.JPG|right|thumb|In the [[Montane ecology|montane forest]] of [[Olympic National Park]], [[windthrow]] opens the [[Canopy (biology)|canopy]] and increases light intensity on the [[understory]].]]
{{See also|Seed dispersal}}
Wind dispersal of seeds, or [[anemochory]], is one of the more primitive means of dispersal. Wind dispersal can take on one of two primary forms: seeds can float on the breeze or alternatively, they can flutter to the ground.<ref>{{cite book|author1=J. Gurevitch |author2=S. M. Scheiner |author3=G. A. Fox |name-list-style=amp |year=2006|title=Plant Ecology, 2nd ed|publisher=Sinauer Associates, Inc., Massachusetts}}</ref> The classic examples of these dispersal mechanisms include [[dandelion]]s (''[[Taraxacum]]'' spp., [[Asteraceae]]), which have a feathery [[pappus (flower structure)|pappus]] attached to their seeds and can be dispersed long distances, and [[maple]]s (''[[Acer (genus)]]'' spp., [[Sapindaceae]]), which have winged seeds and flutter to the ground. An important constraint on wind dispersal is the need for abundant seed production to maximize the likelihood of a seed landing in a site suitable for [[germination]]. There are also strong evolutionary constraints on this dispersal mechanism. For instance, species in the Asteraceae on islands tended to have reduced dispersal capabilities (i.e., larger seed mass and smaller pappus) relative to the same species on the mainland.<ref>{{cite journal|author1=M. L. Cody |author2=J. M. Overton|year=1996|title=Short-term evolution of reduced dispersal in island plant populations|jstor=2261699|doi=10.2307/2261699|journal=Journal of Ecology|volume= 84|issue=1|pages=53–61|bibcode=1996JEcol..84...53C }}</ref> Reliance upon wind dispersal is common among many [[weed]]y or [[ruderal]] species. Unusual mechanisms of wind dispersal include [[tumbleweed]]s. A related process to anemochory is [[anemophily]], which is the process where pollen is distributed by wind. Large families of plants are pollinated in this manner, which is favored when individuals of the dominant plant species are spaced closely together.<ref>{{cite book|url=https://books.google.com/books?id=isLXD8tZ5GMC&pg=PA88|title=Plant Breeding Systems|author=A. J. Richards|publisher=Taylor & Francis|year=1997|isbn=978-0-412-57450-4|access-date=2009-06-19|page=88}}</ref>
Wind also limits tree growth. On coasts and isolated mountains, the tree line is often much lower than in corresponding altitudes inland and in larger, more complex mountain systems, because strong winds reduce tree growth. High winds scour away thin [[soil]]s through erosion,<ref>{{cite journal|url=http://pubs.aina.ucalgary.ca/arctic/Arctic58-3-286.pdf|title=Wind-Conditioned 20th Century Decline of Birch Treeline Vegetation in the Swedish Scandes|journal=Arctic |volume= 58|issue= 3|year= 2005|pages=286–294|access-date=2009-06-20|author=Leif Kullman|doi = 10.14430/arctic430}}</ref> as well as damage limbs and twigs. When high winds knock down or uproot trees, the process is known as [[windthrow]]. This is most likely on [[windward]] slopes of mountains, with severe cases generally occurring to [[tree stand]]s that are 75 years or older.<ref>{{cite journal|doi=10.1139/X08-174|title=Stand-replacing windthrow in the boreal forests of eastern Quebec|author1=Mathieu Bouchard |author2=David Pothier |author3=Jean-Claude Ruel |name-list-style=amp |journal=Canadian Journal of Forest Research|volume=39|issue= 2|year=2009|pages=481–487|bibcode=2009CaJFR..39..481B }}</ref> Plant varieties near the coast, such as the [[Sitka spruce]] and [[Coccoloba uvifera|sea grape]],<ref>{{cite web|url=http://aggie-horticulture.tamu.edu/syllabi/308/Lists/Fourth%20Edition/Coccolobauvifera.pdf|author=Michael A. Arnold|publisher=[[Texas A&M University]]|title=Coccoloba uvifera|year=2009|access-date=2009-06-20|archive-date=2011-06-06|archive-url=https://web.archive.org/web/20110606164352/http://aggie-horticulture.tamu.edu/syllabi/308/Lists/Fourth%20Edition/Coccolobauvifera.pdf|url-status=dead}}</ref> are [[pruning|pruned]] back by wind and salt spray near the coastline.<ref>{{cite web|url=http://www.nps.gov/redw/naturescience/plants.htm|title=Plants|author=[[National Park Service]]|date=2006-09-01|publisher=[[Department of the Interior]]|access-date=2009-06-20}}</ref>
Wind can also cause plants damage through [[sand abrasion]]. Strong winds will pick up loose sand and [[topsoil]] and hurl it through the air at speeds ranging from {{convert|25|mph|kph}} to {{convert|40|mph|kph}}. Such windblown sand causes extensive damage to plant seedlings because it ruptures plant cells, making them vulnerable to evaporation and drought. Using a mechanical sandblaster in a laboratory setting, scientists affiliated with the [[Agricultural Research Service]] studied the effects of windblown sand abrasion on cotton seedlings. The study showed that the seedlings responded to the damage created by the windblown sand abrasion by shifting energy from stem and root growth to the growth and repair of the damaged stems.<ref>[http://www.ars.usda.gov/is/pr/2010/100126.htm ARS Studies Effect of Wind Sandblasting on Cotton Plants / January 26, 2010 / News from the USDA Agricultural Research Service]. Ars.usda.gov. Retrieved 2011-11-03.</ref> After a period of four weeks, the growth of the seedling once again became uniform throughout the plant, as it was before the windblown sand abrasion occurred.<ref>{{cite web
|url= http://www.ars.usda.gov/is/pr/2010/100126.htm
|title= ARS Studies Effect of Wind Sandblasting on Cotton Plants
|publisher=USDA Agricultural Research Service
|date=January 26, 2010}}</ref>
Besides plant gametes (seeds) wind also helps plants' enemies: [[Spore]]s and other [[propagule]]s of [[plant pathogen]]s are even lighter and able to travel long distances.<ref name="Wilson-Talbot-2009">{{cite journal | last1=Wilson | first1=Richard A. | last2=Talbot | first2=Nicholas J. | title=Under pressure: investigating the biology of plant infection by ''Magnaporthe oryzae'' | journal=[[Nature Reviews Microbiology]] | publisher=[[Nature Portfolio]] | volume=7 | issue=3 | year=2009 | issn=1740-1526 | doi=10.1038/nrmicro2032 | pages=185–195| pmid=19219052 | s2cid=42684382 }}</ref> A few plant diseases are known to have been known to travel over [[marginal sea]]s<ref name="Morin-2020">{{cite journal | last=Morin | first=Louise | title=Progress in Biological Control of Weeds with Plant Pathogens | journal=[[Annual Review of Phytopathology]] | publisher=[[Annual Reviews (publisher)|Annual Reviews]] | volume=58 | issue=1 | date=2020-08-25 | issn=0066-4286 | doi=10.1146/annurev-phyto-010820-012823 | pages=201–223| pmid=32384863 | bibcode=2020AnRvP..58..201M | s2cid=218563372 }}</ref> and even entire oceans.<ref name="rust-SAF-Aust">{{cite web | title=Gone with the wind: Revisiting stem rust dispersal between southern Africa and Australia | website=[[GlobalRust]] | url=http://globalrust.org/content/gone-wind-revisiting-stem-rust-dispersal-between-southern-africa-and-australia | access-date=2022-01-03}}</ref> Humans are unable to prevent or even slow down wind dispersal of plant pathogens, requiring prediction and amelioration instead.<ref name="McDonald-Linde-2002">{{cite journal | last1=McDonald | first1=Bruce A. | last2=Linde | first2=Celeste | journal=[[Euphytica]] | publisher=[[Springer Science+Business Media|Springer]] | volume=124 | issue=2 | year=2002 | issn=0014-2336 | doi=10.1023/a:1015678432355 | pages=163–180 | title=The population genetics of plant pathogens and breeding strategies for durable resistance| s2cid=40941822 }}</ref>
=== Effect on animals ===
[[Cattle]] and [[sheep]] are prone to [[wind chill]] caused by a combination of wind and cold temperatures, when winds exceed {{convert|sp=us|40|km/h|mph}}, rendering their hair and wool coverings ineffective.<ref>{{cite journal |pmid=1110212 |title=Wind Chill Effect for Cattle and Sheep |author1=D. R. Ames |author2=L. W. lnsley |name-list-style=amp |journal=Journal of Animal Science |volume=40 |issue=1 |year=1975 |pages=161–165 |doi=10.2527/jas1975.401161x|hdl=2097/10789 |hdl-access=free }}</ref> Although [[penguin]]s use both a layer of [[fat]] and [[feather]]s to help guard against coldness in both water and air, their [[flipper (anatomy)|flippers]] and feet are less immune to the cold. In the coldest climates such as [[Antarctica]], [[emperor penguin]]s use [[kleptothermy|huddling]] behavior to survive the wind and cold, continuously alternating the members on the outside of the assembled group, which reduces heat loss by 50%.<ref>{{cite web|url=http://www.aad.gov.au/default.asp?casid=6216|archive-url=https://web.archive.org/web/20090615181835/http://www.aad.gov.au/default.asp?casid=6216|archive-date=2009-06-15|title=Adapting to the Cold|author=Australian Antarctic Division|access-date=2009-06-20|date=2008-12-08|publisher=Australian Government Department of the Environment, Water, Heritage, and the Arts Australian Antarctic Division}}</ref> Flying [[insect]]s, a subset of [[arthropods]], are swept along by the prevailing winds,<ref>{{cite web|author=Diana Yates|year=2008|url=http://news.illinois.edu/news/08/0707birds.html|title=Birds migrate together at night in dispersed flocks, new study indicates|publisher=[[University of Illinois]] at Urbana – Champaign|access-date=2009-04-26}}</ref> while birds follow their own course taking advantage of wind conditions, in order to either fly or glide.<ref>{{cite web|url=http://people.eku.edu/ritchisong/554notes2.html|title=BIO 554/754 Ornithology Lecture Notes 2 – Bird Flight I|publisher=[[Eastern Kentucky University]]|author=Gary Ritchison|date=2009-01-04|access-date=2009-06-19}}</ref> As such, fine line patterns within [[weather radar]] imagery, associated with converging winds, are dominated by insect returns.<ref>{{cite web|author1=Bart Geerts |author2=Dave Leon |name-list-style=amp |year=2003|url=http://www-das.uwyo.edu/wcr/projects/ihop02/coldfront_preprint.pdf|title=P5A.6 Fine-Scale Vertical Structure of a Cold Front As Revealed By Airborne 95 GHZ Radar|publisher=[[University of Wyoming]]|access-date=2009-04-26}}</ref> Bird migration, which tends to occur overnight within the lowest {{convert|sp=us|7000|ft|m}} of the [[Earth's atmosphere]], contaminates wind profiles gathered by weather radar, particularly the [[WSR-88D]], by increasing the environmental wind returns by {{convert|sp=us|15|kn|km/h}} to {{convert|sp=us|30|kn|km/h}}.<ref>{{cite web|author=Thomas A. Niziol|date=August 1998|url=http://www.erh.noaa.gov/ssd/erps/88d/88dn12.pdf|title=Contamination of WSR-88D VAD Winds Due to Bird Migration: A Case Study|publisher=Eastern Region WSR-88D Operations Note No. 12|access-date=2009-04-26}}</ref>
[[Pika]]s use a wall of pebbles to store dry plants and grasses for the winter in order to protect the food from being blown away.<ref>{{cite book|url=https://archive.org/details/feedingstrategy00owen|url-access=registration|title=Feeding strategy|author=[[Jennifer Owen]]|pages=[https://archive.org/details/feedingstrategy00owen/page/34 34]–35|publisher=University of Chicago Press|year=1982|isbn=978-0-226-64186-7}}</ref> [[Cockroach]]es use slight winds that precede the attacks of potential [[predator]]s, such as [[toad]]s, to survive their encounters. Their [[cercus|cerci]] are very sensitive to the wind, and help them survive half of their attacks.<ref>{{cite book|url=https://books.google.com/books?id=eNdUpgSOWMoC&pg=PA98|title=Neural mechanisms of startle behavior|author=Robert C. Eaton|pages=98–99|publisher=Springer|year=1984|isbn=978-0-306-41556-2|access-date=2009-06-19}}</ref> [[Elk]] have a keen sense of smell that can detect potential upwind predators at a distance of {{convert|sp=us|0.5|mi|m}}.<ref>{{cite book|url=https://books.google.com/books?id=4PbEQvZJ6NQC&pg=PA161|title=The Ultimate Guide to Elk Hunting|author1=Bob Robb |author2=Gerald Bethge |author3=Gerry Bethge |page=161|access-date=2009-06-19|year=2000|publisher=Globe Pequot|isbn=978-1-58574-180-9}}</ref> Increases in wind above {{convert|sp=us|15|km/h|mph}} signals [[glaucous gull]]s to increase their foraging and aerial attacks on thick-billed [[murres]].<ref>{{cite journal|jstor=176831|title=Wind and prey nest sites as foraging constraints on an avian predator, the glaucous gull|author1=H. G. Gilchrist |author2=A. J. Gaston |author3=J. N. M. Smith |name-list-style=amp |journal=Ecology|volume= 79|issue= 7|pages=2403–2414 |year=1998|doi=10.1890/0012-9658(1998)079[2403:WAPNSA]2.0.CO;2}}</ref>
== Related damage ==
{{See also|Severe weather}}
[[File:Destruction following hurricane andrew.jpg|thumb|right|Damage from [[Hurricane Andrew]]]]
High winds are known to cause damage, depending upon the magnitude of their velocity and pressure differential. Wind pressures are positive on the windward side of a structure and negative on the leeward side. Infrequent wind gusts can cause poorly designed [[suspension bridge]]s to sway. When wind gusts are at a similar frequency to the swaying of the bridge, the bridge can be destroyed more easily, such as what occurred with the [[Tacoma Narrows Bridge (1940)|Tacoma Narrows Bridge]] in 1940.<ref>{{cite book|author=T. P. Grazulis|year=2001|url=https://archive.org/details/tornadonaturesul0000graz|url-access=registration|title=The tornado|publisher=[[University of Oklahoma]] Press|pages=[https://archive.org/details/tornadonaturesul0000graz/page/126 126]–127|isbn=978-0-8061-3258-7|access-date=2009-05-13}}</ref> Wind speeds as low as {{convert|sp=us|23|kn|km/h}} can lead to power outages due to tree branches disrupting the flow of energy through power lines.<ref>{{cite book|author1=Hans Dieter Betz |author2=Ulrich Schumann |author3=Pierre Laroche |year=2009|url=https://books.google.com/books?id=U6lCL0CIolYC&pg=PA187|title=Lightning: Principles, Instruments and Applications|publisher=Springer|pages=202–203|isbn=978-1-4020-9078-3|access-date=2009-05-13}}</ref> While no species of tree is guaranteed to stand up to hurricane-force winds, those with shallow roots are more prone to uproot, and brittle trees such as [[eucalyptus]], sea [[hibiscus]], and [[avocado]] are more prone to damage.<ref>{{cite web|author=Derek Burch|url=http://edis.ifas.ufl.edu/EP042|title=How to Minimize Wind Damage in the South Florida Garden|publisher=University of Florida|date=2006-04-26|access-date=2009-05-13}}</ref> Hurricane-force winds cause substantial damage to mobile homes, and begin to structurally damage homes with foundations. Winds of this strength due to downsloped winds off terrain have been known to shatter windows and sandblast paint from cars.<ref name="boulder" /> Once winds exceed {{convert|sp=us|135|kn|km/h}}, homes completely collapse, and significant damage is done to larger buildings. Total destruction to artificial structures occurs when winds reach {{convert|sp=us|175|kn|km/h}}. The [[Saffir–Simpson scale]] and [[Enhanced Fujita scale]] were designed to help estimate wind speed from the damage caused by high winds related to tropical cyclones and [[tornado]]es, and vice versa.<ref name="NHC SSHS">{{cite web|author=[[National Hurricane Center]]|title=Saffir-Simpson Hurricane Scale Information|publisher=[[National Oceanic and Atmospheric Administration]]|date=2006-06-22|url=http://www.nhc.noaa.gov/aboutsshs.shtml|access-date=2007-02-25}}</ref><ref name="EF SPC">{{cite web|title=Enhanced F Scale for Tornado Damage|url=http://www.spc.noaa.gov/efscale/ef-scale.html|access-date=June 21, 2009|publisher=Storm Prediction Center}}</ref>
Australia's [[Barrow Island (Western Australia)|Barrow Island]] holds the record for the strongest wind gust, reaching 408 km/h (253 mph) during tropical [[Cyclone Olivia]] on 10 April 1996, surpassing the previous record of 372 km/h (231 mph) set on [[Mount Washington (New Hampshire)]] on the afternoon of 12 April 1934.<ref>{{cite web|title=Info note No.58 — World Record Wind Gust: 408 km/h |url=http://www.wmo.int/pages/mediacentre/infonotes/info_58_en.html |date=2010-01-22 |publisher=World Meteorological Association |url-status=dead |archive-url=https://web.archive.org/web/20130120065504/http://www.wmo.int/pages/mediacentre/infonotes/info_58_en.html |archive-date=2013-01-20 }}</ref>
Wildfire intensity increases during daytime hours. For example, burn rates of [[smoldering]] logs are up to five times greater during the day because of lower humidity, increased temperatures, and increased wind speeds.<ref>{{cite journal|url=http://www.fs.fed.us/pnw/pubs/journals/pnw_2004_costa001.pdf|author1=Feranando de Souza Costa |author2=David Sandberg |name-list-style=amp |title=Mathematical model of a smoldering log|doi=10.1016/j.combustflame.2004.07.009|journal=Combustion and Flame| issue= 3|volume=139|year=2004|pages=227–238 [228]|bibcode=2004CoFl..139..227D |s2cid=10499171 |access-date=2009-02-06}}</ref> Sunlight warms the ground during the day and causes air currents to travel uphill, and downhill during the night as the land cools. Wildfires are fanned by these winds and often follow the air currents over hills and through valleys.<ref>{{cite book|url=http://www.nifc.gov/PUBLICATIONS/communicators_guide/4%20Communication.PDF|title=NWCG Communicator's Guide for Wildland Fire Management: Fire Education, Prevention, and Mitigation Practices, Wildland Fire Overview|author=National Wildfire Coordinating Group|access-date=2008-12-11|date=2007-02-08|page=5|archive-date=2016-03-04|archive-url=https://web.archive.org/web/20160304074740/http://www.nifc.gov/PUBLICATIONS/communicators_guide/4%20Communication.PDF|url-status=dead}}</ref> United States wildfire operations revolve around a 24-hour ''fire day'' that begins at 10:00 a.m. because of the predictable increase in intensity resulting from the daytime warmth.<ref>{{cite book|url=http://www.nwcg.gov/pms/pubs/glossary/pms205.pdf|archive-url=https://web.archive.org/web/20080821230940/http://www.nwcg.gov/pms/pubs/glossary/pms205.pdf|archive-date=2008-08-21|title=Glossary of Wildland Fire Terminology|author=National Wildfire Coordinating Group|year=2008|access-date=2008-12-18|page=73}}</ref>
== In outer space ==
{{Main|Stellar wind}}
The solar wind is quite different from a terrestrial wind, in that its origin is the Sun, and it is composed of charged particles that have escaped the Sun's atmosphere. Similar to the solar wind, the [[planetary wind]] is composed of light gases that escape planetary atmospheres. Over long periods of time, the planetary wind can radically change the composition of planetary atmospheres.
The fastest wind ever recorded came from the [[accretion disc]] of the [[IGR J17091-3624]] black hole. Its speed is {{convert|20,000,000|mph|kph}}, which is 3% of the [[speed of light]].<ref>{{cite web|url=http://chandra.harvard.edu/press/12_releases/press_022112.html|title=Chandra Finds Fastest Winds from Stellar Black Hole|publisher=NASA|author=Ashley King|display-authors=etal|access-date=September 27, 2012|date=February 21, 2012}}</ref>
=== Planetary wind ===
{{Main|Atmospheric escape}}
[[File:Venuspioneeruv.jpg|thumb|right|A possible future for Earth due to the planetary wind: Venus]]
The hydrodynamic wind within the upper portion of a planet's atmosphere allows light chemical elements such as [[hydrogen]] to move up to the [[exobase]], the lower limit of the [[exosphere]], where the gases can then reach [[escape velocity]], entering outer space without impacting other particles of gas. This type of gas loss from a planet into space is known as planetary wind.<ref>{{cite web|author=Ruth Murray-Clay |year=2008 |url=http://www.bu.edu/csp/NESSC/NESSC_Oct_08/murrayclay_nessc.pdf |archive-url=https://www.webcitation.org/5ilOx5wHu?url=http://www.bu.edu/csp/NESSC/NESSC_Oct_08/murrayclay_nessc.pdf |archive-date=2009-08-04 |title=Atmospheric Escape Hot Jupiters & Interactions Between Planetary and Stellar Winds |publisher=[[Boston University]] |access-date=2009-05-05 |url-status=dead }}</ref> Such a process over [[geologic time]] causes water-rich planets such as the Earth to evolve into planets like [[Venus]].<ref>{{cite journal|author=E. Chassefiere|year=1996|title=Hydrodynamic escape of hydrogen from a hot water-rich atmosphere: The case of Venus|journal=Journal of Geophysical Research|volume= 101|issue=11|pages=26039–26056 |doi=10.1029/96JE01951|bibcode=1996JGR...10126039C}}</ref> Additionally, planets with hotter lower atmospheres could accelerate the loss rate of hydrogen.<ref name="Dvorak">{{cite book|author=Rudolf Dvořák|year=2007|url=https://books.google.com/books?id=lbIlI6gMNAYC&pg=PA140|title=Extrasolar Planets|publisher=Wiley-VCH|pages=139–140|isbn=978-3-527-40671-5|access-date=2009-05-05}}</ref>
=== Solar wind ===
{{Main|Solar wind}}
<!-- [[ new image needed |right|thumb|The [[plasma (physics)|plasma]] in the solar wind meeting the [[heliopause]]]] -->
Rather than air, the solar wind is a [[stream of particles|stream of charged particles]]—a [[plasma (physics)|plasma]]—ejected from the [[stellar atmosphere|upper atmosphere]] of the Sun at a rate of {{convert|sp=us|400|km/s|mph}}.<ref>{{Cite web |title=Solar Wind {{!}} NOAA / NWS Space Weather Prediction Center |url=https://www.swpc.noaa.gov/phenomena/solar-wind |access-date=2023-05-16 |website=www.swpc.noaa.gov}}</ref> It consists mostly of [[electrons]] and [[proton]]s with energies of about 1 [[electron volt|keV]]. The stream of particles varies in temperature and speed with the passage of time. These particles are able to escape the Sun's [[gravity]], in part because of the high [[temperature]] of the [[solar corona|corona]],<ref>{{cite web|author=David H. Hathaway|year=2007|url=http://solarscience.msfc.nasa.gov/SolarWind.shtml|title=The Solar Wind|publisher=[[National Aeronautic and Space Administration]] [[Marshall Space Flight Center]]|access-date=2009-03-19}}</ref> but also because of high kinetic energy that particles gain through a process that is not well understood. The solar wind creates the [[Heliosphere]], a vast bubble in the [[interstellar medium]] surrounding the Solar System.<ref>{{cite news|author=Robert Roy Britt|title=A Glowing Discovery at the Forefront of Our Plunge Through Space|publisher=SPACE.com|date=2000-03-15}}</ref> Planets require large magnetic fields in order to reduce the ionization of their upper atmosphere by the solar wind.<ref name="Dvorak" /> Other phenomena caused by the solar wind include [[geomagnetic storm]]s that can knock out power grids on Earth,<ref>{{cite journal|author=John G. Kappenman|journal=Earth in Space|year= 1997|title=Geomagnetic Storms Can Threaten Electric Power Grid|volume= 9|issue= 7|pages=9–11|access-date=2009-03-19|url =http://www.agu.org/sci_soc/eiskappenman.html|archive-url =https://web.archive.org/web/20080611174103/http://www.agu.org/sci_soc/eiskappenman.html|archive-date =2008-06-11|display-authors=etal}}</ref> the [[aurora (phenomenon)|aurorae]] such as the [[Aurora (astronomy)|Northern Lights]],<ref>{{cite web|author=T. Neil Davis|date=1976-03-22|url=http://www.gi.alaska.edu/ScienceForum/ASF0/015.html|title=Cause of the Aurora|publisher=Alaska Science Forum|access-date=2009-03-19|archive-url=https://web.archive.org/web/20120503184803/http://www2.gi.alaska.edu/ScienceForum/ASF0/015.html|archive-date=2012-05-03|url-status=dead}}</ref> and the plasma tails of [[comet]]s that always point away from the Sun.<ref>{{cite web|author=Donald K. Yeomans|year=2005|publisher=[[National Aeronautics and Space Administration]]|url=http://cmsdev.nasawestprime.com/worldbook/comet_worldbook_prt.htm|archive-url=https://web.archive.org/web/20150321004401/http://cmsdev.nasawestprime.com/worldbook/comet_worldbook_prt.htm|url-status=dead|archive-date=2015-03-21|title=World Book at NASA: Comets|access-date=2009-06-20}}</ref>
== On other planets ==
[[File:The Serpent Dust Devil on Mars PIA15116.jpg|thumb|alt=A towering dust devil on the Martian surface casts a serpentine shadow, illustrating Mars' unique weather conditions.|A [[Martian dust devils|dust devil on Mars]] captured by NASA's HiRISE camera]]
[[File:Perseverance rover's SuperCam records wind on Mars.oga|thumb|Martian wind recorded by the [[Perseverance (rover)|Perseverance rover]]]]
Strong {{convert|sp=us|300|km/h|mph}} winds at Venus's cloud tops circle the planet every four to five Earth days.<ref>{{cite journal |title = Cloud-tracked winds from Pioneer Venus OCPP images |author1=W. B. Rossow, A. D. del Genio, T. Eichler|journal = Journal of the Atmospheric Sciences|volume=47|issue=17|pages=2053–2084|year=1990|doi=10.1175/1520-0469(1990)047<2053:CTWFVO>2.0.CO;2 |bibcode = 1990JAtS...47.2053R|doi-access=free}}</ref> When the poles of [[Mars]] are exposed to sunlight after their winter, the frozen CO<sub>2</sub> [[Sublimation (physics)|sublimates]], creating significant winds that sweep off the poles as fast as {{convert|sp=us|400|km/h|mph}}, which subsequently transports large amounts of dust and water vapor over its [[landscape]].<ref name="clouds">{{cite news|date=2004-12-13|title=Mars Rovers Spot Water-Clue Mineral, Frost, Clouds|url=http://marsrovers.jpl.nasa.gov/gallery/press/opportunity/20041213a.html|author=NASA|access-date=2006-03-17}}</ref> Other Martian winds have resulted in [[cleaning event]]s and [[Spirit rover#Dust devils|dust devils]].<ref>[http://www.nasa.gov/mission_pages/mer/mer-20070314.html NASA – NASA Mars Rover Churns Up Questions With Sulfur-Rich Soil]. Nasa.gov. Retrieved 2011-11-03.</ref><ref>{{cite news|last = David|first = Leonard|date = 12 March 2005|url = http://www.space.com/missionlaunches/spirit_dust_050312.html|title = Spirit Gets A Dust Devil Once-Over|work = Space.com|access-date=2006-12-01}}</ref> On [[Jupiter]], wind speeds of {{convert|sp=us|100|m/s|mph}} are common in zonal jet streams.<ref>{{cite book|author1=A. P. Ingersoll |author2=T. E. Dowling |author3=P. J. Gierasch |author4=G. S. Orton |author5=P. L. Read |author6=A. Sanchez-Lavega |author7=A. P. Showman |author8=A. A. Simon-Miller |author9=A. R. Vasavada |url=http://www.lpl.arizona.edu/~showman/publications/ingersolletal-2004.pdf|title=Dynamics of Jupiter's Atmosphere|publisher=Lunar & Planetary Institute|date=2003-07-29|access-date=2007-02-01}}</ref> Saturn's winds are among the Solar System's fastest. [[Cassini–Huygens]] data indicated peak easterly winds of {{convert|sp=us|375|m/s|mph}}.<ref>{{cite journal|title=Cassini Imaging Science: Initial Results on Saturn's Atmosphere|year=2005|journal=Science|volume=307|pages=1243–1247|doi=10.1126/science.1107691|author=C.C. Porco|pmid=15731441|issue=5713|bibcode = 2005Sci...307.1243P|s2cid=9210768|url=https://resolver.caltech.edu/CaltechAUTHORS:20130125-103208613 |display-authors=etal}}</ref> On [[Uranus]], northern hemisphere wind speeds reach as high as {{convert|sp=us|240|m/s|mph}} near 50 degrees north latitude.<ref name="Sromovsky & Fry 2005">{{cite journal
| doi = 10.1016/j.icarus.2005.07.022
|author1=L. A. Sromovsky |author2=P. M. Fry
|name-list-style=amp | year = 2005
| title = Dynamics of cloud features on Uranus
| journal = Icarus
| volume = 179
| issue = 2
| pages = 459–484
| bibcode = 2005Icar..179..459S
|arxiv=1503.03714}}</ref><ref name="Hammel de Pater et al. Uranus in 2003, 2005">{{cite journal
| doi = 10.1016/j.icarus.2004.11.012
| year = 2005
| author1 = H.B. Hammel
| author2 = I. de Pater
| author3 = S. Gibbard
| author4 = G.W. Lockwoodd
| author5 = K. Rages
| title = Uranus in 2003: Zonal winds, banded structure, and discrete features
| journal = Icarus
| volume = 175
| issue = 2
| pages = 534–545
| url = http://www.llnl.gov/tid/lof/documents/pdf/316112.pdf
| bibcode = 2005Icar..175..534H
| access-date = 2009-06-15
| archive-date = 2007-10-25
| archive-url = https://web.archive.org/web/20071025031013/http://www.llnl.gov/tid/lof/documents/pdf/316112.pdf
| url-status = dead
}}</ref><ref name="Hammel Rages et al. 2001">{{cite journal
| doi = 10.1006/icar.2001.6689
| year = 2001|author1=H.B. Hammel |author2=K. Rages |author3=G.W. Lockwoodd |author4=E. Karkoschka |author5=I. de Pater | title = New Measurements of the Winds of Uranus
| journal = Icarus
| volume = 153
| issue = 2
| pages = 229–235
| bibcode = 2001Icar..153..229H
}}</ref> At the cloud tops of [[Neptune]], prevailing winds range in speed from {{convert|sp=us|400|m/s|mph}} along the equator to {{convert|sp=us|250|m/s|mph}} at the poles.<ref name=elkins-tanton>{{cite book|author=Linda T. Elkins-Tanton|year=2006|title=Uranus, Neptune, Pluto, and the Outer Solar System|publisher=Chelsea House|___location=New York|pages=[https://archive.org/details/uranusneptuneplu00elki/page/79 79–83]|isbn=978-0-8160-5197-7|url=https://archive.org/details/uranusneptuneplu00elki/page/79}}</ref> At 70° S latitude on Neptune, a high-speed jet stream travels at a speed of {{convert|sp=us|300|m/s|mph}}.<ref name="Lunine 1993">{{cite journal
| doi = 10.1146/annurev.aa.31.090193.001245
| author=Jonathan I. Lunine
| year = 1993
| title = The Atmospheres of Uranus and Neptune
| journal = Annual Review of Astronomy and Astrophysics
| volume = 31
| pages = 217–263
| bibcode = 1993ARA&A..31..217L
}}</ref> The fastest wind on any known planet is on [[HD 80606 b]] located 190 [[light year]]s away, where it blows at more than 11,000 mph or 5 km/s.<ref>{{cite news|title=Exoplanet Sees Extreme Heat Waves|url=http://www.space.com/scienceastronomy/090128-hot-planet.html|work=Space.com|date=28 January 2009|access-date=2 September 2017|archive-date=3 June 2009|archive-url=https://web.archive.org/web/20090603003726/http://www.space.com/scienceastronomy/090128-hot-planet.html|url-status=dead}}</ref>
== See also ==
{{columns-list|colwidth=30em|
* [[Airflow]]
* [[Climatology]]
* [[Gale warning|Wind advisory]]
* [[Wind engineering]]
* [[List of local winds]]
* [[North wind]]
* [[South wind]]
* [[West wind]]
* [[East wind]]
}}
== References ==
{{Reflist|30em}}
== External links ==
{{Wikiquote}}
*[https://earth.nullschool.net/#current/wind/surface/level/winkel3/ Current map of global surface winds]
{{Nature}}
{{Meteorological variables}}
{{Authority control}}
[[Category:Wind| ]]
[[Category:Atmospheric dynamics]]
[[Category:Meteorological phenomena]]
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