![Cherry tree moving in the wind 1](https://upload.wikimedia.org/wikipedia/commons/e/e2/Cherry_tree_moving_in_the_wind_1.gif)
Wind is the natural movement of
air or other
gas
Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma).
A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or ...
es relative to a
planet's surface. Winds occur on a range of scales, from
thunderstorm
A thunderstorm, also known as an electrical storm or a lightning storm, is a storm characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere, known as thunder. Relatively weak thunderstorms are someti ...
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
Absorption may refer to:
Chemistry and biology
* Absorption (biology), digestion
**Absorption (small intestine)
*Absorption (chemistry), diffusion of particles of gas or liquid into liquid or solid materials
*Absorption (skin), a route by which ...
of
solar energy
Solar energy is radiant light and heat from the Sun that is harnessed using a range of technologies such as solar power to generate electricity, solar thermal energy (including solar water heating), and solar architecture. It is an essenti ...
between the
climate zones on
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...
. 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
Thermal lows, or heat lows, are non-frontal low-pressure areas that occur over the continents in the subtropics during the warm season, as the result of intense heating when compared to their surrounding environments.Glossary of Meteorology (200 ...
circulations over terrain and high plateaus can drive
monsoon
A monsoon () is traditionally a seasonal reversing wind accompanied by corresponding changes in precipitation but is now used to describe seasonal changes in atmospheric circulation and precipitation associated with annual latitudinal oscil ...
circulations. In coastal areas the
sea breeze
A sea breeze or onshore breeze is any wind that blows from a large body of water toward or onto a landmass; it develops due to differences in air pressure created by the differing heat capacities of water and dry land. As such, sea breezes ar ...
/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
spatial scale
Spatial scale is a specific application of the term scale for describing or categorizing (e.g. into orders of magnitude) the size of a space (hence ''spatial''), or the extent of it at which a phenomenon or process occurs.
For instance, in phy ...
, their
speed
In everyday use and in kinematics, the speed (commonly referred to as ''v'') of an object is the magnitude of the change of its position over time or the magnitude of the change of its position per unit of time; it is thus a scalar quanti ...
and direction, the forces that cause them, the regions in which they occur, and their effect. Winds have various aspects:
velocity
Velocity is the directional speed of an object in motion as an indication of its rate of change in position as observed from a particular frame of reference and as measured by a particular standard of time (e.g. northbound). Velocity is a ...
(
wind speed); the density of the gas involved; energy content, or
wind energy. In
meteorology
Meteorology is a branch of the atmospheric sciences (which include atmospheric chemistry and physics) with a major focus on weather forecasting. The study of meteorology dates back millennia, though significant progress in meteorology did not ...
, 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
gusts. Strong winds of intermediate duration (around one minute) are termed
squalls. Long-duration winds have various names associated with their average strength, such as breeze,
gale,
storm, and
hurricane
A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depend ...
.
In
outer space
Outer space, commonly shortened to space, is the expanse that exists beyond Earth and its atmosphere and between celestial bodies. Outer space is not completely empty—it is a near-perfect vacuum containing a low density of particles, pred ...
,
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
A chemical element is a species of atoms that have a given number of protons in their nuclei, including the pure substance consisting only of that species. Unlike chemical compounds, chemical elements cannot be broken down into simpler sub ...
s from a planet's atmosphere into space. The strongest observed winds on a planet in the
Solar System
The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Solar S ...
occur on
Neptune
Neptune is the eighth planet from the Sun and the farthest known planet in the Solar System. It is the fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 times ...
and
Saturn
Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius of about nine and a half times that of Earth. It has only one-eighth the average density of Earth; h ...
.
In human civilization, the concept of wind has been explored in
mythology
Myth is a folklore genre consisting of narratives that play a fundamental role in a society, such as foundational tales or origin myths. Since "myth" is widely used to imply that a story is not objectively true, the identification of a narrat ...
, influenced the events of history, expanded the range of transport and warfare, and provided a
power source for mechanical work, electricity, and recreation. Wind powers the voyages of
sailing ship
A sailing ship is a sea-going vessel that uses sails mounted on masts to harness the power of wind and propel the vessel. There is a variety of sail plans that propel sailing ships, employing square-rigged or fore-and-aft sails. Some ships c ...
s across Earth's oceans.
Hot air balloons 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
Loess (, ; from german: Löss ) is a clastic, predominantly silt-sized sediment that is formed by the accumulation of wind-blown dust. Ten percent of Earth's land area is covered by loess or similar deposits.
Loess is a periglacial or aeolian ...
, and by
erosion
Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is distin ...
. 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
![10 PM March 12 surface analysis of Great Blizzard of 1888](https://upload.wikimedia.org/wikipedia/commons/a/a8/10_PM_March_12_surface_analysis_of_Great_Blizzard_of_1888.png)
Wind is caused by differences in atmospheric pressure, which are mainly due to temperature difference. When a
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
Solar energy is radiant light and heat from the Sun that is harnessed using a range of technologies such as solar power to generate electricity, solar thermal energy (including solar water heating), and solar architecture. It is an essenti ...
leading to
buoyancy force
Buoyancy (), or upthrust, is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus the ...
s) and the
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
Friction is the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding against each other. There are several types of friction:
*Dry friction is a force that opposes the relative lateral motion of t ...
causes the wind to be slower than it would be otherwise. Surface friction also causes winds to blow more inward into low-pressure areas.
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
In physics, equations of motion are equations that describe the behavior of a physical system in terms of its motion as a function of time.''Encyclopaedia of Physics'' (second Edition), R.G. Lerner, G.L. Trigg, VHC Publishers, 1991, ISBN (Ver ...
and for making qualitative arguments about the horizontal and vertical distribution of horizontal winds. The
geostrophic wind
In atmospheric science, geostrophic flow () is the theoretical wind that would result from an exact balance between the Coriolis force and the pressure gradient force. This condition is called '' geostrophic equilibrium'' or ''geostrophic balanc ...
component is the result of the balance between Coriolis force and pressure gradient force. It flows parallel to
isobars and approximates the flow above the
atmospheric boundary layer
In meteorology, the planetary boundary layer (PBL), also known as the atmospheric boundary layer (ABL) or peplosphere, is the lowest part of the atmosphere and its behaviour is directly influenced by its contact with a planetary surface. On Ear ...
in the midlatitudes. 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
A temperature gradient is a physical quantity that describes in which direction and at what rate the temperature changes the most rapidly around a particular location. The temperature gradient is a dimensional quantity expressed in units of degree ...
s. The
ageostrophic wind component is the difference between actual and geostrophic wind, which is responsible for air "filling up" cyclones over time. The
gradient wind
In atmospheric science, balanced flow is an idealisation of atmospheric motion. The idealisation consists in considering the behaviour of one isolated parcel of air having constant density, its motion on a horizontal plane subject to selected for ...
is similar to the geostrophic wind but also includes
centrifugal force
In Newtonian mechanics, the centrifugal force is an inertial force (also called a "fictitious" or "pseudo" force) that appears to act on all objects when viewed in a rotating frame of reference. It is directed away from an axis which is paralle ...
(or
centripetal acceleration).
Measurement
Wind direction
Wind direction is generally reported by the direction from which it originates. For example, a ''north'' or ''northerly'' wind blows from the north to the south. The exceptions are onshore winds (blowing onto the shore from the water) and offsho ...
is usually expressed in terms of the direction from which it originates. For example, a ''northerly'' wind blows from the north to the south.
Weather vane
A wind vane, weather vane, or weathercock is an instrument used for showing the direction of the wind. It is typically used as an architectural ornament to the highest point of a building. The word ''vane'' comes from the Old English word , m ...
s pivot to indicate the direction of the wind. At airports,
windsocks indicate wind direction, and can also be used to estimate wind speed by the angle of hang. Wind speed is measured by
anemometers, 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
Ultrasound is sound waves with frequency, frequencies higher than the upper audible limit of human hearing range, hearing. Ultrasound is not different from "normal" (audible) sound in its physical properties, except that humans cannot hea ...
signals or by the effect of ventilation on the resistance of a heated wire. Another type of anemometer uses
pitot tubes 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.
Sustained wind speeds are reported globally at a height and are averaged over a 10‑minute time frame. The United States reports winds over a 1‑minute average for tropical cyclones,
and a 2‑minute average within weather observations.
[Office of the Federal Coordinator for Meteorology]
Federal Meteorological Handbook No. 1 – Surface Weather Observations and Reports September 2005
Appendix A: Glossary. Retrieved 2008-04-06. India typically reports winds over a 3‑minute average. 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. 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 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,
rawinsondes
A radiosonde is a battery-powered telemetry instrument carried into the atmosphere usually by a weather balloon that measures various atmospheric parameters and transmits them by radio to a ground receiver. Modern radiosondes measure or calculat ...
determine wind speed by
GPS
The Global Positioning System (GPS), originally Navstar GPS, is a Radionavigation-satellite service, satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of t ...
,
radio navigation, or
radar
Radar is a detection system that uses radio waves to determine the distance (''ranging''), angle, and radial velocity of objects relative to the site. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, w ...
tracking of the probe. Alternatively, movement of the parent
weather balloon
A weather balloon, also known as sounding balloon, is a balloon (specifically a type of high-altitude balloon) that carries instruments aloft to send back information on atmospheric pressure, temperature, humidity and wind speed by means of a ...
position can be tracked from the ground visually using
theodolite
A theodolite () is a precision optical instrument for measuring angles between designated visible points in the horizontal and vertical planes. The traditional use has been for land surveying, but it is also used extensively for building and i ...
s.
Remote sensing
Remote sensing is the acquisition of information about an object or phenomenon without making physical contact with the object, in contrast to in situ or on-site observation. The term is applied especially to acquiring information about Earth ...
techniques for wind include
SODAR,
Doppler lidar
Lidar (, also LIDAR, or LiDAR; sometimes LADAR) is a method for determining ranges (variable distance) by targeting an object or a surface with a laser and measuring the time for the reflected light to return to the receiver. It can also be ...
s and radars, which can measure the
Doppler shift
The Doppler effect or Doppler shift (or simply Doppler, when in context) is the change in frequency of a wave in relation to an observer who is moving relative to the wave source. It is named after the Austrian physicist Christian Doppler, who d ...
of
electromagnetic radiation
In physics, electromagnetic radiation (EMR) consists of waves of the electromagnetic field, electromagnetic (EM) field, which propagate through space and carry momentum and electromagnetic radiant energy. It includes radio waves, microwaves, inf ...
scattered or reflected off suspended
aerosol
An aerosol is a suspension (chemistry), suspension of fine solid particles or liquid Drop (liquid), droplets in air or another gas. Aerosols can be natural or Human impact on the environment, anthropogenic. Examples of natural aerosols are fog o ...
s or
molecule
A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioch ...
s, and
radiometer
A radiometer or roentgenometer is a device for measuring the radiant flux (power) of electromagnetic radiation. Generally, a radiometer is an infrared radiation detector or an ultraviolet detector. Microwave radiometers operate in the microwave w ...
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
Wind engineering is a subset of mechanical engineering, structural engineering, meteorology, and applied physics that analyzes the effects of wind in the natural and the built environment and studies the possible damage, inconvenience or benefits w ...
describes the study of the effects of the wind on the built environment, including buildings, bridges and other artificial objects.
Wind force scale
Historically, the
Beaufort wind force scale (created by
Beaufort Beaufort may refer to:
People and titles
* Beaufort (surname)
* House of Beaufort, English nobility
* Duke of Beaufort (England), a title in the peerage of England
* Duke of Beaufort (France), a title in the French nobility
Places Polar regions ...
) provides an empirical description of wind speed based on observed sea conditions. Originally it was a 13-level scale (0-12), but during the 1940s, the scale was expanded to 18 levels (0-17).
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 and with preceding adjectives such as moderate, fresh, strong, and whole used to differentiate the wind's strength within the gale category. A storm has winds of to . 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 Centers worldwide:
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 some other countries with small modifications (among which include Canada and France).
Station model
![Wind barbs](https://upload.wikimedia.org/wikipedia/commons/c/c6/Wind_barbs.gif)
The
station model plotted on surface
weather map
A weather map, also known as synoptic weather chart, displays various meteorological features across a particular area at a particular point in time and has various symbols which all have specific meanings. Such maps have been in use since the m ...
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 of wind.
* Each full flag depicts of wind.
* Each
pennant (filled triangle) depicts of wind.
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.
Once plotted on a map, an analysis of
isotach
A contour line (also isoline, isopleth, or isarithm) of a function of two variables is a curve along which the function has a constant value, so that the curve joins points of equal value. It is a plane section of the three-dimensional grap ...
s (lines of equal wind speeds) can be accomplished. Isotachs are particularly useful in diagnosing the location of the
jet stream
Jet streams are fast flowing, narrow, meandering thermal wind, air currents in the Atmosphere of Earth, atmospheres of some planets, including Earth. On Earth, the main jet streams are located near the altitude of the tropopause and are west ...
on upper-level constant pressure charts, and are usually located at or above the 300 hPa level.
Global climatology
![Earth Global Circulation](https://upload.wikimedia.org/wikipedia/commons/6/6d/Earth_Global_Circulation.jpg)
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
The horse latitudes are the latitudes about 30 degrees north and south of the Equator. They are characterized by sunny skies, calm winds, and very little precipitation. They are also known as Subtropics, subtropical ridges, or highs. It is a h ...
, while easterlies again dominate the
tropics
The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in
the Southern Hemisphere at S. The tropics are also referred to ...
.
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
Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present.
Humidity depe ...
of the air mass. The strongest winds are in the mid-latitudes where cold polar air meets warm air from the tropics.
Tropics
The trade winds (also called trades) are the prevailing pattern of
easterly surface winds found in the tropics towards the Earth's
equator
The equator is a circle of latitude, about in circumference, that divides Earth into the Northern and Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the North and South poles. The term can als ...
. The trade winds blow predominantly from the northeast in the Northern Hemisphere and from the southeast in the Southern Hemisphere.
The trade winds act as the
steering flow for
tropical cyclones that form over the world's oceans. Trade winds also steer African dust westward across the Atlantic Ocean into the Caribbean, as well as portions of southeast North America.
A
monsoon
A monsoon () is traditionally a seasonal reversing wind accompanied by corresponding changes in precipitation but is now used to describe seasonal changes in atmospheric circulation and precipitation associated with annual latitudinal oscil ...
is a seasonal prevailing wind that lasts for several months within tropical regions. The term was first used in English in India,
Bangladesh
Bangladesh (}, ), officially the People's Republic of Bangladesh, is a country in South Asia. It is the eighth-most populous country in the world, with a population exceeding 165 million people in an area of . Bangladesh is among the mos ...
, Pakistan, and neighboring countries to refer to the big seasonal winds blowing from the
Indian Ocean
The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by th ...
and
Arabian Sea
The Arabian Sea ( ar, اَلْبَحرْ ٱلْعَرَبِيُّ, Al-Bahr al-ˁArabī) is a region of the northern Indian Ocean bounded on the north by Pakistan, Iran and the Gulf of Oman, on the west by the Gulf of Aden, Guardafui Channel ...
in the southwest bringing heavy rainfall to the area. 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.
Westerlies and their impact
![Franklingulfstream](https://upload.wikimedia.org/wikipedia/commons/4/45/Franklingulfstream.jpg)
The Westerlies or the Prevailing Westerlies are the
prevailing winds in the
middle latitudes
The middle latitudes (also called the mid-latitudes, sometimes midlatitudes, or moderate latitudes) are a spatial region on Earth located between the Tropic of Cancer (latitudes 23°26'22") to the Arctic Circle (66°33'39"), and Tropic of Caprico ...
between 35 and 65 degrees
latitude
In geography, latitude is a coordinate that specifies the north– south position of a point on the surface of the Earth or another celestial body. Latitude is given as an angle that ranges from –90° at the south pole to 90° at the north pol ...
. These prevailing winds blow from the west to the east, 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.
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.
Together with the
trade winds, 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
Boundary currents are ocean currents with dynamics determined by the presence of a coastline, and fall into two distinct categories: western boundary currents and eastern boundary currents.
Eastern boundary currents
Eastern boundary currents are ...
. These western ocean currents transport warm, sub-tropical water polewards toward the
polar region
The polar regions, also called the frigid geographical zone, zones or polar zones, of Earth are the regions of the planet that surround its geographical poles (the North Pole, North and South Poles), lying within the polar circles. These high l ...
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
40 and
50 degrees latitude south of the equator. The Westerlies play an important role in carrying the warm, equatorial waters and winds to the western coasts of continents,
especially in the southern hemisphere because of its vast oceanic expanse.
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 highs at the
north
North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating Direction (geometry), direction or geography.
Etymology
T ...
and
south pole
The South Pole, also known as the Geographic South Pole, Terrestrial South Pole or 90th Parallel South, is one of the two points where Earth's axis of rotation intersects its surface. It is the southernmost point on Earth and lies antipod ...
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. Because of the low sun angle, cold air builds up and
subsides at the pole creating surface high-pressure areas, forcing an equatorward outflow of air; that outflow is deflected westward by the Coriolis effect.
Local considerations
Sea and land breezes
![Diagrama de formacion de la brisa-breeze](https://upload.wikimedia.org/wikipedia/commons/9/9b/Diagrama_de_formacion_de_la_brisa-breeze.svg)
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
In thermodynamics, the specific heat capacity (symbol ) of a substance is the heat capacity of a sample of the substance divided by the mass of the sample, also sometimes referred to as massic heat capacity. Informally, it is the amount of heat t ...
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. 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.
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.
Near mountains
![Vol d'onde](https://upload.wikimedia.org/wikipedia/commons/5/58/Vol_d%27onde.svg)
Over elevated surfaces, heating of the ground exceeds the heating of the surrounding air at the same altitude above
sea level
Mean sea level (MSL, often shortened to sea level) is an average surface level of one or more among Earth's coastal bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datuma standardised g ...
, creating an associated thermal low over the terrain and enhancing any thermal lows that would have otherwise existed, and changing the wind circulation of the region. In areas where there is rugged
topography
Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the land forms and features themselves, or a description or depiction in maps.
Topography is a field of geoscience and planetary sci ...
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
Jet streams are fast flowing, narrow, meandering air currents in the atmospheres of some planets, including Earth. On Earth, the main jet streams are located near the altitude of the tropopause and are westerly winds (flowing west to east). ...
. This barrier jet can increase the low-level wind by 45%. Wind direction also changes because of the contour of the land.
If there is a
pass
Pass, PASS, The Pass or Passed may refer to:
Places
*Pass, County Meath, a townland in Ireland
* Pass, Poland, a village in Poland
*Pass, an alternate term for a number of straits: see List of straits
*Mountain pass, a lower place in a mountai ...
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
An airplane or aeroplane (informally plane) is a fixed-wing aircraft that is propelled forward by thrust from a jet engine, propeller, or rocket engine. Airplanes come in a variety of sizes, shapes, and wing configurations. The broad spe ...
s.
Cool winds accelerating through mountain gaps have been given regional names. In Central America, examples include the
Papagayo wind
The Papagayo jet, also referred to as the Papagayo Wind or the Papagayo Wind Jet, are strong intermittent winds that blow approximately 70 km north of the Gulf of Papagayo, after which they are named. The jet winds travel southwest from the ...
, the
Panama
Panama ( , ; es, link=no, Panamá ), officially the Republic of Panama ( es, República de Panamá), is a transcontinental country spanning the southern part of North America and the northern part of South America. It is bordered by Cos ...
wind, and the
Tehuano wind
Tehuantepecer, or Tehuano wind, is a violent mountain-gap wind that travels through the Chivela Pass in southern Mexico, across the Isthmus of Tehuantepec. It is most common between October and February, with a summer minimum in July. It originate ...
. In Europe, similar winds are known as the
Bora,
Tramontane, and
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.
In mountainous areas, local distortion of the airflow becomes severe. Jagged terrain combines to produce unpredictable flow patterns and turbulence, such as
rotors, which can be topped by
lenticular clouds. Strong
updrafts, downdrafts, and
eddies
In fluid dynamics, an eddy is the swirling of a fluid and the reverse current created when the fluid is in a turbulent flow regime. The moving fluid creates a space devoid of downstream-flowing fluid on the downstream side of the object. Fluid beh ...
develop as the air flows over hills and down valleys. Orographic
precipitation
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. ...
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 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
Windward () and leeward () are terms used to describe the direction of the wind. Windward is ''upwind'' from the point of reference, i.e. towards the direction from which the wind is coming; leeward is ''downwind'' from the point of reference ...
or downwind side. Moisture is removed by orographic lift, leaving drier air on the descending and generally warming, leeward side where a
rain shadow
A rain shadow is an area of significantly reduced rainfall behind a mountainous region, on the side facing away from prevailing winds, known as its leeward side.
Evaporated moisture from water bodies (such as oceans and large lakes) is carrie ...
is observed.
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
The Alps () ; german: Alpen ; it, Alpi ; rm, Alps ; sl, Alpe . are the highest and most extensive mountain range system that lies entirely in Europe, stretching approximately across seven Alpine countries (from west to east): France, Sw ...
, they are known as
foehn
A Foehn or Föhn (, , ), is a type of dry, relatively warm, downslope wind that occurs in the lee (downwind side) of a mountain range.
It is a rain shadow wind that results from the subsequent adiabatic warming of air that has dropped most of ...
. In Poland, an example is the
halny wiatr. In Argentina, the local name for down sloped winds is
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. In the Great Plains of the United States, these winds are known as a
chinook. Downslope winds also occur in the foothills of the Appalachian mountains of the United States, and they can be as strong as other downslope winds and unusual compared to other
foehn winds
A Foehn or Föhn (, , ), is a type of dry, relatively warm, downslope wind that occurs in the lee (downwind side) of a mountain range.
It is a rain shadow wind that results from the subsequent adiabatic warming of air that has dropped most of ...
in that the relative humidity typically changes little due to the increased moisture in the source air mass. In California, downslope winds are funneled through mountain passes, which intensify their effect, and examples include the
Santa Ana and
sundowner winds. Wind speeds during downslope wind effect can exceed .
Shear
![Hodographe NOAA](https://upload.wikimedia.org/wikipedia/commons/2/21/Hodographe_NOAA.PNG)
Wind shear, sometimes referred to as
wind gradient
In common usage, wind gradient, more specifically wind speed gradient
or wind velocity gradient,
or alternatively shear wind,
is the vertical component of the gradient of the mean horizontal wind speed in the lower atmosphere. It is the rate of ...
, is a difference in wind speed and direction over a relatively short distance in the Earth's atmosphere. Wind shear can be broken down into vertical and horizontal components, with horizontal wind shear seen across
weather fronts and near the coast,
and vertical shear typically near the surface, though also at higher levels in the atmosphere near upper level jets and frontal zones aloft.
Wind shear itself is a
microscale meteorological phenomenon occurring over a very small distance, but it can be associated with
mesoscale or
synoptic scale weather features such as
squall lines and
cold fronts. It is commonly observed near
microbursts and
downbursts caused by
thunderstorm
A thunderstorm, also known as an electrical storm or a lightning storm, is a storm characterized by the presence of lightning and its acoustic effect on the Earth's atmosphere, known as thunder. Relatively weak thunderstorms are someti ...
s,
weather fronts, areas of locally higher low level winds referred to as low level jets, near mountains, radiation inversions that occur because of clear skies and calm winds, buildings,
wind turbine
A wind turbine is a device that converts the kinetic energy of wind into electrical energy. Hundreds of thousands of large turbines, in installations known as wind farms, now generate over 650 gigawatts of power, with 60 GW added each year. ...
s, and
sailboat
A sailboat or sailing boat is a boat propelled partly or entirely by sails and is smaller than a sailing ship. Distinctions in what constitutes a sailing boat and ship vary by region and maritime culture.
Types
Although sailboat terminology ...
s. Wind shear has a significant effect on the control of aircraft during take-off and landing, and was a significant cause of aircraft accidents involving large loss of life within the United States.
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. Strong vertical wind shear within the troposphere also inhibits
tropical cyclone
A tropical cyclone is a rapidly rotating storm system characterized by a low-pressure center, a closed low-level atmospheric circulation, strong winds, and a spiral arrangement of thunderstorms that produce heavy rain and squalls. Depend ...
development, but helps to organize individual thunderstorms into living longer life cycles that can then produce
severe weather. 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
Jet streams are fast flowing, narrow, meandering thermal wind, air currents in the Atmosphere of Earth, atmospheres of some planets, including Earth. On Earth, the main jet streams are located near the altitude of the tropopause and are west ...
.
In civilization
Religion
As a natural force, the wind was often personified as one or more
wind god
A wind god is a god who controls the wind(s). Air deities may also be considered here as wind is nothing more than moving air. Many polytheistic religions have one or more wind gods. They may also have a separate air god or a wind god may doub ...
s or as an expression of the
supernatural
Supernatural refers to phenomena or entities that are beyond the laws of nature. The term is derived from Medieval Latin , from Latin (above, beyond, or outside of) + (nature) Though the corollary term "nature", has had multiple meanings si ...
in many cultures.
Vayu
Vayu (, sa, वायु, ), also known as Vata and Pavana, is the Hindu god of the winds as well as the divine massenger of the gods. In the ''Vedic scriptures'', Vayu is an important deity and is closely associated with Indra, the king of ...
is the
Vedic
upright=1.2, The Vedas are ancient Sanskrit texts of Hinduism. Above: A page from the '' Atharvaveda''.
The Vedas (, , ) are a large body of religious texts originating in ancient India. Composed in Vedic Sanskrit, the texts constitute the ...
and Hindu God of Wind.
The Greek wind gods include
Boreas,
Notus
In ancient Greek religion and myth, the Anemoi (Greek: , 'Winds') were wind gods who were each ascribed a cardinal direction from which their respective winds came (see Classical compass winds), and were each associated with various seasons and ...
,
Eurus, and
Zephyrus.
Aeolus
In Greek mythology, Aeolus or Aiolos (; grc, Αἴολος , ) is a name shared by three mythical characters. These three personages are often difficult to tell apart, and even the ancient mythographers appear to have been perplexed about which A ...
, in varying interpretations the ruler or keeper of the four winds, has also been described as
Astraeus
In Greek mythology, Astraeus () or Astraios (Ancient Greek: Ἀστραῖος means "starry"') was an astrological deity. Some also associate him with the winds, as he is the father of the four Anemoi (wind deities), by his wife, Eos.
Etymolog ...
, the god of dusk who fathered the four winds with
Eos
In ancient Greek mythology and religion, Eos (; Ionic and Homeric Greek ''Ēṓs'', Attic ''Héōs'', "dawn", or ; Aeolic ''Aúōs'', Doric ''Āṓs'') is the goddess and personification of the dawn, who rose each morning from her home ...
, goddess of dawn. The
ancient Greeks
Ancient Greece ( el, Ἑλλάς, Hellás) was a northeastern Mediterranean civilization, existing from the Greek Dark Ages of the 12th–9th centuries BC to the end of classical antiquity ( AD 600), that comprised a loose collection of cultu ...
also observed the seasonal change of the winds, as evidenced by the
Tower of the Winds in
Athens
Athens ( ; el, Αθήνα, Athína ; grc, Ἀθῆναι, Athênai (pl.) ) is both the capital and largest city of Greece. With a population close to four million, it is also the seventh largest city in the European Union. Athens dominates ...
.
Venti are the Roman gods of the winds.
Fūjin
or is the Japanese god of the wind and one of the eldest Shinto gods. He is portrayed as a terrifying wizardly demon, resembling a red-headed green-skinned humanoid wearing a leopard skin, carrying a large bag of winds on his shoulders. In Ja ...
is the Japanese wind god and is one of the eldest
Shinto
Shinto () is a religion from Japan. Classified as an East Asian religion by scholars of religion, its practitioners often regard it as Japan's indigenous religion and as a nature religion. Scholars sometimes call its practitioners ''Shintois ...
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. In
Norse mythology
Norse, Nordic, or Scandinavian mythology is the body of myths belonging to the North Germanic peoples, stemming from Old Norse religion and continuing after the Christianization of Scandinavia, and into the Nordic folklore of the modern period ...
,
Njörðr is the god of the wind.
There are also four dvärgar (
Norse dwarves
A dwarf () is a type of supernatural being in Germanic folklore, including mythology. Accounts of dwarfs vary significantly throughout history however they are commonly, but not exclusively, presented as living in mountains or stones and being ski ...
), named
Norðri, Suðri, Austri and Vestri, and probably the
four stags of Yggdrasil
4 (four) is a number, numeral and digit. It is the natural number following 3 and preceding 5. It is the smallest semiprime and composite number, and is considered unlucky in many East Asian cultures.
In mathematics
Four is the smallest c ...
, personify the four winds, and parallel the four Greek wind gods.
Stribog
Stribog is a god in Slavic mythology found in three East Slavic sources, whose cult may also have existed in Poland. The sources do not inform about the functions of the god, but nowadays he is most often interpreted as a wind deity who distribut ...
is the name of the
Slavic god of winds, sky and air. He is said to be the ancestor (grandfather) of the winds of the eight directions.
History
Kamikaze
, officially , were a part of the Japanese Special Attack Units of military aviators who flew suicide attacks for the Empire of Japan against Allied naval vessels in the closing stages of the Pacific campaign of World War II, intending to d ...
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.
Protestant Wind
The phrase Protestant Wind has been used in more than one context, notably:
#The storm that lashed the Spanish Armada in 1588. The wind wrecked the Spanish fleet and thus saved England from invasion by the army of Philip II of Spain. The English m ...
is a name for the storm that deterred the
Spanish Armada
The Spanish Armada (a.k.a. the Enterprise of England, es, Grande y Felicísima Armada, links=no, lit=Great and Most Fortunate Navy) was a Spanish fleet that sailed from Lisbon in late May 1588, commanded by the Duke of Medina Sidonia, an aris ...
from an invasion of England in 1588 where the wind played a pivotal role, or the favorable winds that enabled
William of Orange to invade England in 1688. During
Napoleon
Napoleon Bonaparte ; it, Napoleone Bonaparte, ; co, Napulione Buonaparte. (born Napoleone Buonaparte; 15 August 1769 – 5 May 1821), later known by his regnal name Napoleon I, was a French military commander and political leader who ...
's
Egyptian Campaign, the French soldiers had a hard time with the
khamsin
Khamsin, chamsin or hamsin ( ar, خمسين , meaning "fifty"), more commonly known in Egypt as khamaseen ( arz, خماسين , ), is a dry, hot, sandy local wind affecting Egypt and the Levant; similar winds, blowing in other parts of North ...
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". 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."
Transportation
![Exeter-20may44](https://upload.wikimedia.org/wikipedia/commons/c/c7/Exeter-20may44.jpg)
There are many different forms of sailing ships, but they all have certain basic things in common. Except for
rotor ships using the
Magnus effect, every sailing ship has a
hull
Hull may refer to:
Structures
* Chassis, of an armored fighting vehicle
* Fuselage, of an aircraft
* Hull (botany), the outer covering of seeds
* Hull (watercraft), the body or frame of a ship
* Submarine hull
Mathematics
* Affine hull, in affi ...
,
rigging
Rigging comprises the system of ropes, cables and chains, which support a sailing ship or sail boat's masts—''standing rigging'', including shrouds and stays—and which adjust the position of the vessel's sails and spars to which they are ...
and at least one
mast
Mast, MAST or MASt may refer to:
Engineering
* Mast (sailing), a vertical spar on a sailing ship
* Flagmast, a pole for flying a flag
* Guyed mast, a structure supported by guy-wires
* Mooring mast, a structure for docking an airship
* Radio mast ...
to hold up the
sail
A sail is a tensile structure—which is made from fabric or other membrane materials—that uses wind power to propel sailing craft, including sailing ships, sailboats, windsurfers, ice boats, and even sail-powered land vehicles. Sails may ...
s that use the wind to power the ship. Ocean journeys by sailing ship can take many months, and a common hazard is becoming becalmed because of lack of wind, or being blown off course by severe
storms or winds that do not allow progress in the desired direction. A severe storm could lead to
shipwreck
A shipwreck is the wreckage of a ship that is located either beached on land or sunken to the bottom of a body of water. Shipwrecking may be intentional or unintentional. Angela Croome reported in January 1999 that there were approximately ...
, and the loss of all hands. Sailing ships can only carry a certain quantity of supplies in their
hold
Hold may refer to:
Physical spaces
* Hold (ship), interior cargo space
* Baggage hold, cargo space on an airplane
* Stronghold, a castle or other fortified place
Arts, entertainment, and media
* Hold (musical term), a pause, also called a Fermat ...
, so they have to plan long
voyages carefully to include appropriate
provisions, including fresh water.
For
aerodynamic aircraft which operate relative to the air, winds affect groundspeed, and in the case of lighter-than-air vehicles, wind may play a significant or solitary role in their movement and
ground track. The
velocity
Velocity is the directional speed of an object in motion as an indication of its rate of change in position as observed from a particular frame of reference and as measured by a particular standard of time (e.g. northbound). Velocity is a ...
of surface wind is generally the primary factor governing the direction of flight operations at an airport, and
airfield
An aerodrome (Commonwealth English) or airdrome (American English) is a location from which aircraft flight operations take place, regardless of whether they involve air cargo, passengers, or neither, and regardless of whether it is for publ ...
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.
Power source
![Windenergy](https://upload.wikimedia.org/wikipedia/commons/e/e0/Windenergy.jpg)
The ancient
Sinhalese
Sinhala may refer to:
* Something of or related to the Sinhalese people of Sri Lanka
* Sinhalese people
* Sinhala language, one of the three official languages used in Sri Lanka
* Sinhala script, a writing system for the Sinhala language
** Sinha ...
of
Anuradhapura
Anuradhapura ( si, අනුරාධපුරය, translit=Anurādhapuraya; ta, அனுராதபுரம், translit=Aṉurātapuram) is a major city located in north central plain of Sri Lanka. It is the capital city of North Central ...
and in other cities around
Sri Lanka
Sri Lanka (, ; si, ශ්රී ලංකා, Śrī Laṅkā, translit-std=ISO (); ta, இலங்கை, Ilaṅkai, translit-std=ISO ()), formerly known as Ceylon and officially the Democratic Socialist Republic of Sri Lanka, is an ...
used the monsoon winds to power furnaces as early as 300
BCE. The furnaces were constructed on the path of the monsoon winds to bring the temperatures inside up to . A rudimentary
windmill was used to power an
organ
Organ may refer to:
Biology
* Organ (biology), a part of an organism
Musical instruments
* Organ (music), a family of keyboard musical instruments characterized by sustained tone
** Electronic organ, an electronic keyboard instrument
** Hammond ...
in the first century CE. Windmills were later built in
Sistan
Sistān ( fa, سیستان), known in ancient times as Sakastān ( fa, سَكاستان, "the land of the Saka"), is a historical and geographical region in present-day Eastern Iran ( Sistan and Baluchestan Province) and Southern Afghanistan (N ...
,
Afghanistan
Afghanistan, officially the Islamic Emirate of Afghanistan,; prs, امارت اسلامی افغانستان is a landlocked country located at the crossroads of Central Asia and South Asia. Referred to as the Heart of Asia, it is bordere ...
, from the 7th century CE. These were vertical-axle windmills, with
sails covered in
reed matting or cloth material. These windmills were used to grind corn and draw up water, and were used in the
gristmill
A gristmill (also: grist mill, corn mill, flour mill, feed mill or feedmill) grinds cereal grain into flour and Wheat middlings, middlings. The term can refer to either the Mill (grinding), grinding mechanism or the building that holds it. Grist i ...
ing and sugarcane industries. 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
Renewable energy is energy that is collected from renewable resources that are naturally replenished on a human timescale. It includes sources such as sunlight, wind, the movement of water, and geothermal heat. Although most renewable energy ...
, and its use is growing rapidly, driven by innovation and falling prices. Most of the installed capacity in wind power is
onshore, but
offshore wind power offers a large potential as wind speeds are typically higher and more constant away from the coast. Wind energy the
kinetic energy
In physics, the kinetic energy of an object is the energy that it possesses due to its motion.
It is defined as the work needed to accelerate a body of a given mass from rest to its stated velocity. Having gained this energy during its accele ...
of the air, is proportional to the third power of wind velocity.
Betz's law
Betz's law indicates the maximum power that can be extracted from the wind, independent of the design of a wind turbine in open flow. It was published in 1919 by the German physicist Albert Betz. The law is derived from the principles of conserva ...
described the theoretical upper limit of what fraction of this energy wind turbines can extract, which is about 59%.
Recreation
![Lilienthal in flight](https://upload.wikimedia.org/wikipedia/commons/3/3e/Lilienthal_in_flight.jpg)
Wind figures prominently in several popular sports, including recreational
hang gliding,
hot air ballooning
Hot air ballooning is the activity of flying hot air balloons. Attractive aspects of ballooning include the exceptional quiet (except when the propane burners are firing), the lack of a feeling of movement, and the bird's-eye view. Since the b ...
,
kite flying,
snowkiting,
kite landboarding,
kite surfing,
paragliding,
sailing
Sailing employs the wind—acting on sails, wingsails or kites—to propel a craft on the surface of the ''water'' (sailing ship, sailboat, raft, windsurfer, or kitesurfer), on ''ice'' (iceboat) or on ''land'' (land yacht) over a chosen cour ...
, and
windsurfing
Windsurfing is a wind propelled water sport that is a combination of sailing and surfing. It is also referred to as "sailboarding" and "boardsailing", and emerged in the late 1960s from the aerospace and surf culture of California. Windsurfing ga ...
. In gliding, wind gradients just above the surface affect the takeoff and landing phases of flight of a
glider
Glider may refer to:
Aircraft and transport Aircraft
* Glider (aircraft), heavier-than-air aircraft primarily intended for unpowered flight
** Glider (sailplane), a rigid-winged glider aircraft with an undercarriage, used in the sport of glidin ...
. Wind gradient can have a noticeable effect on
ground launch
Gliding is a recreational activity and competitive air sport in which pilots fly unpowered aircraft known as gliders or sailplanes using naturally occurring currents of rising air in the atmosphere to remain airborne. The word ''soaring'' is al ...
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. 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.
In the natural world
In arid climates, the main source of erosion is wind.
The general wind circulation moves small particulates such as dust across wide oceans thousands of kilometers downwind of their point of origin,
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
![Im Salar de Uyuni](https://upload.wikimedia.org/wikipedia/commons/0/09/Im_Salar_de_Uyuni.jpg)
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. Loess is a homogeneous, typically nonstratified, porous,
friable, slightly coherent, often calcareous, fine-grained,
silt
Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water. Silt usually has a floury feel when ...
y, pale yellow or buff, windblown (Aeolian)
sediment
Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand an ...
. 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. Loess tends to develop into highly rich soils. Under appropriate climatic conditions, areas with loess are among the most agriculturally productive in the world. Loess deposits are geologically unstable by nature, and will erode very readily. Therefore,
windbreak
A windbreak (shelterbelt) is a planting usually made up of one or more rows of trees or shrubs planted in such a manner as to provide shelter from the wind and to protect soil from erosion. They are commonly planted in hedgerows around the edges ...
s (such as big trees and bushes) are often planted by farmers to reduce the wind erosion of loess.
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
, photo = Sahara real color.jpg
, photo_caption = The Sahara taken by Apollo 17 astronauts, 1972
, map =
, map_image =
, location =
, country =
, country1 =
, ...
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.
Over 50% of the African dust that reaches the United States affects Florida. 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. Dust events have been linked to a decline in the health of
coral reef
A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups.
Co ...
s across the Caribbean and Florida, primarily since the 1970s. Similar dust plumes originate in the
Gobi Desert
The Gobi Desert (Chinese: 戈壁 (沙漠), Mongolian: Говь (ᠭᠣᠪᠢ)) () is a large desert or brushland region in East Asia, and is the sixth largest desert in the world.
Geography
The Gobi measures from southwest to northeast an ...
, which combined with pollutants, spread large distances downwind, or eastward, into North America.
There are local names for winds associated with sand and dust storms. The Calima carries dust on southeast winds into the
Canary islands
The Canary Islands (; es, Canarias, ), also known informally as the Canaries, are a Spanish autonomous community and archipelago in the Atlantic Ocean, in Macaronesia. At their closest point to the African mainland, they are west of Morocc ...
. The
Harmattan
The Harmattan is a season in West Africa that occurs between the end of November and the middle of March. It is characterized by the dry and dusty northeasterly trade wind, of the same name, which blows from the Sahara over West Africa into the ...
carries dust during the winter into the
Gulf of Guinea
The Gulf of Guinea is the northeasternmost part of the tropical Atlantic Ocean from Cape Lopez in Gabon, north and west to Cape Palmas in Liberia. The intersection of the Equator and Prime Meridian (zero degrees latitude and longitude) is in the ...
. The
Sirocco brings dust from north Africa into southern Europe because of the movement of extratropical cyclones through the Mediterranean. Spring storm systems moving across the eastern Mediterranean Sea cause dust to carry across
Egypt
Egypt ( ar, مصر , ), officially the Arab Republic of Egypt, is a transcontinental country spanning the northeast corner of Africa and southwest corner of Asia via a land bridge formed by the Sinai Peninsula. It is bordered by the Mediter ...
and the
Arabian peninsula
The Arabian Peninsula, (; ar, شِبْهُ الْجَزِيرَةِ الْعَرَبِيَّة, , "Arabian Peninsula" or , , "Island of the Arabs") or Arabia, is a peninsula of Western Asia, situated northeast of Africa on the Arabian Plate ...
, which are locally known as
Khamsin
Khamsin, chamsin or hamsin ( ar, خمسين , meaning "fifty"), more commonly known in Egypt as khamaseen ( arz, خماسين , ), is a dry, hot, sandy local wind affecting Egypt and the Levant; similar winds, blowing in other parts of North ...
. The
Shamal is caused by cold fronts lifting dust into the atmosphere for days at a time across the
Persian Gulf
The Persian Gulf ( fa, خلیج فارس, translit=xalij-e fârs, lit=Gulf of Persis, Fars, ), sometimes called the ( ar, اَلْخَلِيْجُ ٱلْعَرَبِيُّ, Al-Khalīj al-ˁArabī), is a Mediterranean sea (oceanography), me ...
states.
Effect on plants
![Coarse woody debris 6407](https://upload.wikimedia.org/wikipedia/commons/0/09/Coarse_woody_debris_6407.JPG)
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. The classic examples of these dispersal mechanisms include
dandelions (''
Taraxacum'' spp.,
Asteraceae
The family Asteraceae, alternatively Compositae, consists of over 32,000 known species of flowering plants in over 1,900 genera within the order Asterales. Commonly referred to as the aster, daisy, composite, or sunflower family, Compositae w ...
), which have a feathery
pappus attached to their seeds and can be dispersed long distances, and
maple
''Acer'' () is a genus of trees and shrubs commonly known as maples. The genus is placed in the family Sapindaceae.Stevens, P. F. (2001 onwards). Angiosperm Phylogeny Website. Version 9, June 2008 nd more or less continuously updated since http ...
s (''
Acer (genus)
''Acer'' () is a genus of trees and shrubs commonly known as maples. The genus is placed in the family Sapindaceae.Stevens, P. F. (2001 onwards). Angiosperm Phylogeny Website. Version 9, June 2008 nd more or less continuously updated since http ...
'' spp.,
Sapindaceae
The Sapindaceae are a family of flowering plants in the order Sapindales known as the soapberry family. It contains 138 genera and 1858 accepted species. Examples include horse chestnut, maples, ackee and lychee.
The Sapindaceae occur in tempera ...
), 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
Germination is the process by which an organism grows from a seed or spore. The term is applied to the sprouting of a seedling from a seed of an angiosperm or gymnosperm, the growth of a sporeling from a spore, such as the spores of fungi, fer ...
. 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. Reliance upon wind dispersal is common among many
weedy or
ruderal species. Unusual mechanisms of wind dispersal include
tumbleweed
A tumbleweed is a structural part of the above-ground anatomy of a number of species of plants. It is a diaspore that, once mature and dry, detaches from its root or stem and rolls due to the force of the wind. In most such species, the tumble ...
s. A related process to anemochory is
anemophily
Anemophily or wind pollination is a form of pollination whereby pollen is distributed by wind. Almost all gymnosperms are anemophilous, as are many plants in the order Poales, including grasses, sedges, and rushes. Other common anemophilous plan ...
, 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.
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
Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former te ...
s through erosion, 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
Tree stands or deer stands are open or enclosed platforms used by hunters. The platforms are secured to trees in order to elevate the hunter and give them a better vantage point. A tripod stand is a similar device, but because it is freestanding ...
s that are 75 years or older. Plant varieties near the coast, such as the
Sitka spruce
''Picea sitchensis'', the Sitka spruce, is a large, coniferous, evergreen tree growing to almost tall, with a trunk diameter at breast height that can exceed 5 m (16 ft). It is by far the largest species of spruce and the fifth-larg ...
and
sea grape, are
pruned
Pruning is a horticultural, arboricultural, and silvicultural practice involving the selective removal of certain parts of a plant, such as branches, buds, or roots.
The practice entails the ''targeted'' removal of diseased, damaged, dead, ...
back by wind and salt spray near the coastline.
Wind can also cause plants damage through
sand abrasion
Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of s ...
. Strong winds will pick up loose sand and
topsoil
Topsoil is the upper layer of soil. It has the highest concentration of organic matter and microorganisms and is where most of the Earth's biological soil activity occurs.
Description
Topsoil is composed of mineral particles and organic matt ...
and hurl it through the air at speeds ranging from to . 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
The Agricultural Research Service (ARS) is the principal in-house research agency of the United States Department of Agriculture (USDA). ARS is one of four agencies in USDA's Research, Education and Economics mission area. ARS is charged with ext ...
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. 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.
Besides plant gametes (seeds) wind also helps plants' enemies:
Spore
In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, f ...
s and other
propagule
In biology, a propagule is any material that functions in propagating an organism to the next stage in its life cycle, such as by dispersal. The propagule is usually distinct in form from the parent organism. Propagules are produced by organisms ...
s of
plant pathogen
Plant pathology (also phytopathology) is the scientific study of diseases in plants caused by pathogens (infectious organisms) and environmental conditions (physiological factors). Organisms that cause infectious disease include fungi, oomyc ...
s are even lighter and able to travel long distances.
A few plant diseases are known to have been known to travel over
marginal seas
and even entire oceans.
Humans are unable to prevent or even slow down wind dispersal of plant pathogens, requiring prediction and amelioration instead.
Effect on animals
Cattle
Cattle (''Bos taurus'') are large, domesticated, cloven-hooved, herbivores. They are a prominent modern member of the subfamily Bovinae and the most widespread species of the genus ''Bos''. Adult females are referred to as cows and adult mal ...
and
sheep
Sheep or domestic sheep (''Ovis aries'') are domesticated, ruminant mammals typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus ''Ovis'', in everyday usage it almost always refers to domesticated s ...
are prone to
wind chill
Wind chill or windchill (popularly wind chill factor) is the lowering of body temperature due to the passing-flow of lower-temperature air.
Wind chill numbers are always lower than the air temperature for values where the formula is valid. When ...
caused by a combination of wind and cold temperatures, when winds exceed , rendering their hair and wool coverings ineffective. Although
penguin
Penguins (order (biology), order List of Sphenisciformes by population, Sphenisciformes , family (biology), family Spheniscidae ) are a group of Water bird, aquatic flightless birds. They live almost exclusively in the Southern Hemisphere: on ...
s use both a layer of
fat
In nutrition science, nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such chemical compound, compounds, most commonly those that occur in living beings or in food.
The term often refers spec ...
and
feather
Feathers are epidermal growths that form a distinctive outer covering, or plumage, on both avian (bird) and some non-avian dinosaurs and other archosaurs. They are the most complex integumentary structures found in vertebrates and a premier ...
s to help guard against coldness in both water and air, their
flippers and feet are less immune to the cold. In the coldest climates such as
Antarctica
Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean, it contains the geographic South Pole. Antarctica is the fifth-largest contine ...
,
emperor penguin
The emperor penguin (''Aptenodytes forsteri'') is the tallest and heaviest of all living penguin species and is endemic to Antarctica. The male and female are similar in plumage and size, reaching in length and weighing from . Feathers of th ...
s use
huddling
In biology, kleptothermy is any form of thermoregulation by which an animal shares in the metabolic thermogenesis of another animal. It may or may not be reciprocal, and occurs in both endotherms and ectotherms. One of its forms is huddling. Howe ...
behavior to survive the wind and cold, continuously alternating the members on the outside of the assembled group, which reduces heat loss by 50%. Flying
insect
Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...
s, a subset of
arthropods
Arthropods (, (gen. ποδός)) are invertebrate animals with an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Arthropoda. They are distinguished by their jointed limbs and Arth ...
, are swept along by the prevailing winds, while birds follow their own course taking advantage of wind conditions, in order to either fly or glide. As such, fine line patterns within
weather radar
Weather radar, also called weather surveillance radar (WSR) and Doppler weather radar, is a type of radar used to locate precipitation, calculate its motion, and estimate its type (rain, snow, hail etc.). Modern weather radars are mostly puls ...
imagery, associated with converging winds, are dominated by insect returns. Bird migration, which tends to occur overnight within the lowest of the
Earth's atmosphere
The atmosphere of Earth is the layer of gases, known collectively as air, retained by Earth's gravity that surrounds the planet and forms its planetary atmosphere. The atmosphere of Earth protects life on Earth by creating pressure allowing for ...
, contaminates wind profiles gathered by weather radar, particularly the
WSR-88D, by increasing the environmental wind returns by to .
Pikas use a wall of pebbles to store dry plants and grasses for the winter in order to protect the food from being blown away.
Cockroach
Cockroaches (or roaches) are a paraphyletic group of insects belonging to Blattodea, containing all members of the group except termites. About 30 cockroach species out of 4,600 are associated with human habitats. Some species are well-known as ...
es use slight winds that precede the attacks of potential
predator
Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill th ...
s, such as
toad
Toad is a common name for certain frogs, especially of the family Bufonidae, that are characterized by dry, leathery skin, short legs, and large bumps covering the parotoid glands.
A distinction between frogs and toads is not made in scientif ...
s, to survive their encounters. Their
cerci are very sensitive to the wind, and help them survive half of their attacks.
Elk
The elk (''Cervus canadensis''), also known as the wapiti, is one of the largest species within the deer family, Cervidae, and one of the largest terrestrial mammals in its native range of North America and Central and East Asia. The common ...
have a keen sense of smell that can detect potential upwind predators at a distance of . Increases in wind above signals
glaucous gull
The glaucous gull (''Larus hyperboreus'') is a large gull, the second-largest gull in the world. It breeds in Arctic regions of the Northern Hemisphere and winters south to shores of the Holarctic. The genus name is from Latin ''larus'', which a ...
s to increase their foraging and aerial attacks on thick-billed
murres
''Uria'' is a genus of seabirds in the auk family known in Britain as guillemots, in most of North America as murres, and in Newfoundland and Labrador as turr. These are medium-sized birds with mainly brown or black plumage in the breeding sea ...
.
Related damage
![Destruction following hurricane andrew](https://upload.wikimedia.org/wikipedia/commons/6/63/Destruction_following_hurricane_andrew.jpg)
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
A suspension bridge is a type of bridge in which the deck (bridge), deck is hung below suspension wire rope, cables on vertical suspenders. The first modern examples of this type of bridge were built in the early 1800s. Simple suspension bridg ...
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
The Tacoma Narrows Bridge is a pair of twin suspension bridges that span the Tacoma Narrows strait of Puget Sound in Pierce County, Washington. The bridges connect the city of Tacoma with the Kitsap Peninsula and carry State Route 16 (known ...
in 1940. Wind speeds as low as can lead to power outages due to tree branches disrupting the flow of energy through power lines. 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
''Eucalyptus'' () is a genus of over seven hundred species of flowering trees, shrubs or mallees in the myrtle family, Myrtaceae. Along with several other genera in the tribe Eucalypteae, including '' Corymbia'', they are commonly known as euca ...
, sea
hibiscus, and
avocado
The avocado (''Persea americana'') is a medium-sized, evergreen tree in the laurel family (Lauraceae). It is native to the Americas and was first domesticated by Mesoamerican tribes more than 5,000 years ago. Then as now it was prized for i ...
are more prone to damage. 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.
Once winds exceed , homes completely collapse, and significant damage is done to larger buildings. Total destruction to artificial structures occurs when winds reach . 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
A tornado is a violently rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. It is often referred to as a twister, whirlwind or cyclone, altho ...
es, and vice versa.
Australia's
Barrow Island Barrow Island may refer to:
* Barrow Island (Western Australia), Australia
* Barrow Island (Queensland), Australia
* Barrow Island, Barrow-in-Furness
Barrow Island is an area and electoral ward of Barrow-in-Furness, Cumbria, England. Originall ...
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)
Mount Washington is the highest peak in the Northeastern United States at and the most topographically prominent mountain east of the Mississippi River.
The mountain is notorious for its erratic weather. On the afternoon of April 12, 1934, ...
on the afternoon of 12 April 1934.
Wildfire intensity increases during daytime hours. For example, burn rates of
smoldering
Smouldering (British English) or smoldering (American English; see spelling differences) is the slow, flameless form of combustion, sustained by the heat evolved when oxygen directly attacks the surface of a condensed-phase fuel. Many solid mate ...
logs are up to five times greater during the day because of lower humidity, increased temperatures, and increased wind speeds. 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. 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.
In outer space
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
IGR J17091-3624 (also IGR J17091) is a stellar mass black hole 28,000 light-years away. It lies in the constellation Scorpius in the Milky Way galaxy.
Discovery
IGR J17091 was discovered by ESA's INTEGRAL satellite in April 2003.
Descrip ...
black hole. Its speed is , which is 3% of the
speed of light
The speed of light in vacuum, commonly denoted , is a universal physical constant that is important in many areas of physics. The speed of light is exactly equal to ). According to the special theory of relativity, is the upper limit ...
.
Planetary wind
![Venuspioneeruv](https://upload.wikimedia.org/wikipedia/commons/b/bc/Venuspioneeruv.jpg)
The hydrodynamic wind within the upper portion of a planet's atmosphere allows light chemical elements such as
hydrogen
Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic, an ...
to move up to the
exobase, the lower limit of the
exosphere
The exosphere ( grc, ἔξω "outside, external, beyond", grc, σφαῖρα "sphere") is a thin, atmosphere-like volume surrounding a planet or natural satellite where molecules are gravitationally bound to that body, but where the densit ...
, 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. Such a process over
geologic time
The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochrono ...
causes water-rich planets such as the Earth to evolve into planets like
Venus
Venus is the second planet from the Sun. It is sometimes called Earth's "sister" or "twin" planet as it is almost as large and has a similar composition. As an interior planet to Earth, Venus (like Mercury) appears in Earth's sky never fa ...
. Additionally, planets with hotter lower atmospheres could accelerate the loss rate of hydrogen.
Solar wind
Rather than air, the solar wind is a
stream of charged particles—a
plasma
Plasma or plasm may refer to:
Science
* Plasma (physics), one of the four fundamental states of matter
* Plasma (mineral), a green translucent silica mineral
* Quark–gluon plasma, a state of matter in quantum chromodynamics
Biology
* Blood pla ...
—ejected from the
upper atmosphere Upper atmosphere is a collective term that refers to various layers of the atmosphere of the Earth above the troposphere and corresponding regions of the atmospheres of other planets, and includes:
* The mesosphere, which on Earth lies between the ...
of the sun at a rate of . It consists mostly of
electrons
The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family,
and are generally thought to be elementary particles because they have no ...
and
proton
A proton is a stable subatomic particle, symbol , H+, or 1H+ with a positive electric charge of +1 ''e'' elementary charge. Its mass is slightly less than that of a neutron and 1,836 times the mass of an electron (the proton–electron mass ...
s with energies of about 1
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 physics, gravity () is a fundamental interaction which causes mutual attraction between all things with mass or energy. Gravity is, by far, the weakest of the four fundamental interactions, approximately 1038 times weaker than the stro ...
, in part because of the high
temperature
Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer.
Thermometers are calibrated in various temperature scales that historically have relied o ...
of the
corona, 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
In astronomy, the interstellar medium is the matter and radiation that exist in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as dust and cosmic rays. It fills interstella ...
surrounding the Solar System. Planets require large magnetic fields in order to reduce the ionization of their upper atmosphere by the solar wind.
Other phenomena caused by the solar wind include
geomagnetic storms that can knock out power grids on Earth, the
aurorae
An aurora (plural: auroras or aurorae), also commonly known as the polar lights, is a natural light display in Earth's sky, predominantly seen in polar regions of Earth, high-latitude regions (around the Arctic and Antarctic). Auroras display ...
such as the
Northern Lights, and the plasma tails of
comet
A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena ar ...
s that always point away from the Sun.
On other planets
Strong winds at Venus's cloud tops circle the planet every four to five earth days. When the poles of
Mars
Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury (planet), Mercury. In the English language, Mars is named for the Mars (mythology), Roman god of war. Mars is a terr ...
are exposed to sunlight after their winter, the frozen CO
2 sublimates, creating significant winds that sweep off the poles as fast as , which subsequently transports large amounts of dust and water vapor over its
landscape
A landscape is the visible features of an area of land, its landforms, and how they integrate with natural or man-made features, often considered in terms of their aesthetic appeal.''New Oxford American Dictionary''. A landscape includes the ...
.
Other Martian winds have resulted in
cleaning events and
dust devils. On
Jupiter
Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but ...
, wind speeds of are common in zonal jet streams. Saturn's winds are among the Solar System's fastest.
Cassini–Huygens
''Cassini–Huygens'' ( ), commonly called ''Cassini'', was a space research, space-research mission by NASA, the European Space Agency (ESA), and the Italian Space Agency (ASI) to send a space probe to study the planet Saturn and its system, i ...
data indicated peak easterly winds of . On
Uranus
Uranus is the seventh planet from the Sun. Its name is a reference to the Greek god of the sky, Uranus (mythology), Uranus (Caelus), who, according to Greek mythology, was the great-grandfather of Ares (Mars (mythology), Mars), grandfather ...
, northern hemisphere wind speeds reach as high as near 50 degrees north latitude.
At the cloud tops of
Neptune
Neptune is the eighth planet from the Sun and the farthest known planet in the Solar System. It is the fourth-largest planet in the Solar System by diameter, the third-most-massive planet, and the densest giant planet. It is 17 times ...
, prevailing winds range in speed from along the equator to at the poles.
At 70° S latitude on Neptune, a high-speed jet stream travels at a speed of .
The fastest wind on any known planet is on
HD 80606 b
HD 80606 b (also Struve 1341 B b or HIP 45982 b) is an eccentric and hot Jupiter 190 light-years from the Sun in the constellation of Ursa Major. HD 80606 b was discovered orbiting the star HD 80606 in April 2001 by a team led by Michel Mayor an ...
located 190
light year
A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...
s away, where it blows at more than 11,000 mph or 5 km/s.
See also
References
External links
Current map of global surface winds
{{Authority control
Atmospheric dynamics
Meteorological phenomena