Citizendia
Your Ad Here

For the Marvel Comics character, see Windshear (comics). Windshear ( Colin Ashworth Hume) is a Fictional character, a Superhero in the Marvel Comics universe.
Cirrus uncinus ice crystal plumes showing high level wind shear, with changes in wind speed and direction.
Cirrus uncinus ice crystal plumes showing high level wind shear, with changes in wind speed and direction. Cirrus clouds are characterized by thin wisplike strands often accompanied by tufts leading to their common (non-standard name of 'mare's tail'

Wind shear, sometimes referred to as windshear or wind gradient, is a difference in wind speed and direction over a relatively short distance in the atmosphere. In common usage wind gradient, more specifically wind speed gradient or wind velocity gradient,or alternatively shear wind,is the vertical Wind is the flow of Air or other Gases that compose an Atmosphere (including but not limited to the Earth's) Wind speed is the Speed of Wind, the movement of air or other gases in an atmosphere Wind direction is the direction from which the Wind is blowing Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five 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. A weather front is a boundary separating two masses of air of different densities, and is the principal cause of meteorological phenomena.

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. Microscale meteorology is the study of atmospheric phenomena smaller than mesoscale, about 1 Km or less Mesoscale Meteorology is the study of Weather systems smaller than Synoptic scale systems but larger than microscale and Storm-scale cumulus The synoptic scale in Meteorology (also known as large scale or cyclonic scale) is a horizontal length scale of the order of 1000 kilometres (about 620 It is commonly observed near microbursts and downbursts caused by thunderstorms, weather fronts, areas of locally higher low level winds referred to as low level jets, near mountains, radiation inversions that occur due to clear skies and calm winds, buildings, wind turbines, and sailboats. A microburst is a very localized column of sinking air producing damaging divergent and Straight-line winds at the surface that are similar to but distinguishable from Downburst damagejpg|thumb|right|300px|Downburst damages in a straight line A mountain is a Landform that extends above the surrounding Terrain in a limited area with a peak Wind shear has a significant effect during take-off and landing of aircraft due to their effects on steering of the aircraft, and was a significant cause of aircraft accidents involving large loss of life within the United States. The United States of America —commonly referred to as the

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 development, but helps to organize individual thunderstorms into living longer life cycles which can then produce severe weather. A tropical cyclone is a storm system characterized by a low pressure center and numerous Thunderstorms that produce strong winds and Flooding Severe weather is any destructive weather phenomenon. The term is usually used to refer to severe thunderstorms and related phenomena such as Tornados The thermal wind concept explains with how differences in wind speed with height are dependent on horizontal temperature differences, and explains the existence of the jet stream. The thermal wind is a Vertical shear in the Geostrophic wind caused by a Horizontal Temperature gradient. Jet streams are fast flowing relatively narrow air currents found at the Tropopause, the transition between the Troposphere (where temperature decreases [1]

Contents

Definition

Wind shear refers to the variation of wind over either horizontal or vertical distances. Airplane pilots generally regard significant windshear to be a horizontal change in airspeed of 30 knots (15 m/s) for light aircraft, and near 45 knots (22 m/s) for airliners. [2] Vertical speed changes greater than 4. 9 knots (2. 5 m/s) also qualify as significant wind shear for aircraft. Low level wind shear can affect aircraft airspeed during take off and landing in disastrous ways. [3] It is also a key factor in the creation of severe thunderstorms. The additional hazard of turbulence is often associated with wind shear. In Fluid dynamics, turbulence or turbulent flow is a fluid regime characterized by chaotic Stochastic property changes

Where and when it is strongly observed

See also: Jet stream
Microburst schematic from NASA. Note the downward motion of the air until it hits ground level, then spreads outward in all directions. The wind regime in a microburst is completely opposite to a tornado.
Microburst schematic from NASA. Jet streams are fast flowing relatively narrow air currents found at the Tropopause, the transition between the Troposphere (where temperature decreases A microburst is a very localized column of sinking air producing damaging divergent and Straight-line winds at the surface that are similar to but distinguishable from Note the downward motion of the air until it hits ground level, then spreads outward in all directions. The wind regime in a microburst is completely opposite to a tornado.

Weather situations where shear is observed include:

Horizontal component

Weather fronts

Main article: Weather fronts

Weather fronts are boundaries between two masses of air of different densities, or different temperature and moisture properties, which normally are convergence zones in the wind field and are the principal cause of significant weather. A weather front is a boundary separating two masses of air of different densities, and is the principal cause of meteorological phenomena. The density of a material is defined as its Mass per unit Volume: \rho = \frac{m}{V} Different materials usually have different For convergence zones of sonars see Sonar#Sound_propagation. Convergence zone usually refers to a region in the atmosphere where two prevailing Within surface weather analyses, they are depicted using various colored lines and symbols. The air masses usually differ in temperature and may also differ in humidity. Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature Humidity is the amount of water vapor in the air In daily language the term "humidity" is normally taken to mean Relative humidity. Wind shear in the horizontal occurs near these boundaries. Cold fronts feature narrow bands of thunderstorms and severe weather, and may be preceded by squall lines and dry lines. A cold front defined as the leading edge of a cooler and drier mass of air Severe weather is any destructive weather phenomenon. The term is usually used to refer to severe thunderstorms and related phenomena such as Tornados A squall line is a line of severe thunderstorms that can form along and/or ahead of a Cold front. A dry line, (also called dew point line, or Marfa front) is an important factor in Severe weather frequency in the Great Plains of Cold fronts are sharper surface boundaries with more significant horizontal wind shear than warm fronts. When a front becomes stationary, it can degenerate into a line which separates regions of differing wind speed, known as a shear line, though the wind direction across the feature normally remains constant. A stationary front is a boundary between two different Air masses neither of which is strong enough to replace the other In the tropics, tropical waves move from east to west across the Atlantic and eastern Pacific basins. The Tropics are centered on the Equator and limited in Latitude by the Tropic of Cancer in the northern hemisphere at approximately 23°26' (23 Tropical waves, or easterly waves, also known as African easterly waves in the Atlantic region are a type of Atmospheric trough, The Pacific Ocean is the largest of the Earth 's Oceanic divisions Directional and speed shear can occur across the axis of stronger tropical waves, as northerly winds precede the wave axis and southeast winds are seen behind the wave axis. Horizontal wind shear can also occur along local land breeze and sea breeze boundaries. A sea-breeze (or onshore breeze) is a Wind from the sea that develops over land near coasts [9]

Near coastlines

The magnitude of winds offshore are nearly double the wind speed observed onshore. This is attributed to the differences in friction between land masses and offshore waters. Sometimes, there are even directional differences, particularly if local sea breezes change the wind on shore during daylight hours. [10]

Vertical component

Thermal wind

Main article: Thermal wind

Thermal wind is a meteorological term not referring to an actual wind, but a difference in the geostrophic wind between two pressure levels p1 and p0, with p1 < p0; in essence, wind shear. The thermal wind is a Vertical shear in the Geostrophic wind caused by a Horizontal Temperature gradient. Wind is the flow of Air or other Gases that compose an Atmosphere (including but not limited to the Earth's) The geostrophic wind is the Theoretical Wind that would result from an exact balance between the Coriolis force and the Pressure gradient force Geopotential height is a vertical coordinate referenced to Earth's Mean sea level — an adjustment to geometric height ( Elevation above mean sea level using the It is only present in an atmosphere with horizontal changes in temperature (or in an ocean with horizontal gradients of density), i. Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature The density of a material is defined as its Mass per unit Volume: \rho = \frac{m}{V} Different materials usually have different e. baroclinicity. In Fluid dynamics, the baroclinity (sometimes called baroclinicity) is a measure of the Stratification in a fluid In a barotropic atmosphere, where temperature is uniform, the geostrophic wind is independent of height. In Meteorology, a barotropic atmosphere is one in which the pressure depends only on the density and vice versa so that isobaric surfaces (constant pressure surfaces The name stems from the fact that this wind flows around areas of low (and high) temperature in the same manner as the geostrophic wind flows around areas of low (and high) pressure. The geostrophic wind is the Theoretical Wind that would result from an exact balance between the Coriolis force and the Pressure gradient force A low pressure area, or " low " is a region where the Atmospheric pressure is lower in relation to the surrounding area A high pressure area (also called a high or high-pressure is a region where the Atmospheric pressure is greater than surrounding areas Pressure (symbol 'p' is the force per unit Area applied to an object in a direction perpendicular to the surface [11]

The thermal wind equation is

f \mathbf{v}_T = \mathbf{k} \times \nabla ( \phi_1 - \phi_0 ),

where the φx are geopotential height fields with φ1 > φ0, f is the Coriolis parameter, and \mathbf{k} is the upward-pointing unit vector in the vertical direction. Geopotential height is a vertical coordinate referenced to Earth's Mean sea level — an adjustment to geometric height ( Elevation above mean sea level using the The Coriolis frequency, f, is equal to twice the rotation rate of the Earth multiplied by the Sine of the Latitude. In Mathematics, a unit vector in a Normed vector space is a vector (often a spatial vector) whose length is 1 (the unit length In Astronomy, Geography, Geometry and related sciences and contexts a direction passing by a given point is said to be vertical if The thermal wind equation does not determine the wind in the tropics. The Tropics are centered on the Equator and limited in Latitude by the Tropic of Cancer in the northern hemisphere at approximately 23°26' (23 Since f is small or zero, such as near the equator, the equation reduces to stating that \nabla ( \phi_1 - \phi_0 ) is small. [11]

This equation basically describes the existence of the jet stream, a westerly current of air with maximum wind speeds close to the tropopause which is (even though other factors are also important) the result of the temperature contrast between equator and pole. The tropopause is in the atmosphere between the Troposphere and the Stratosphere.

Effects on tropical cyclones

Main article: Tropical cyclogenesis

Tropical cyclones are basically heat engines that are fueled by the temperature gradient between the warm tropical ocean surface and the colder upper atmosphere. Tropical cyclogenesis is the technical term describing the development and strengthening of a Tropical cyclone in the Atmosphere. A tropical cyclone is a storm system characterized by a low pressure center and numerous Thunderstorms that produce strong winds and Flooding A heat engine is a physical or theoretical device that converts Thermal energy to mechanical output In atmospheric sciences ( Meteorology, Climatology and related fields the temperature gradient (typically of air, more generally of any Fluid Tropical cyclone development requires relatively low values of vertical wind shear so that their warm core can remain above their surface circulation center, thereby promoting strengthening. Vertical wind shear tears up the "machinery" of the heat engine causing it to break down. Strongly sheared tropical cyclones weaken as the upper circulation is blown away from the low level center. [12]

Strong wind shear in the high troposphere forms the anvil-shaped top of the mature cumulonimbus cloud, or thunderstorm. The anvil may stretch several kilometers downwind in the direction of the shear.
Strong wind shear in the high troposphere forms the anvil-shaped top of the mature cumulonimbus cloud, or thunderstorm. The troposphere is the lowest portion of Earth's atmosphere. It contains approximately 75% of the atmosphere's mass and almost all of its Water vapor and Cumulonimbus (Cb is a type of Cloud that is tall dense and involved in Thunderstorms and other intense Weather. The anvil may stretch several kilometers downwind in the direction of the shear. [13]

Effects on thunderstorms and severe weather

Main article: Severe thunderstorm

Severe thunderstorms, which can spawn tornadoes and hailstorms, require wind shear to organize the storm in such a way as to maintain the thunderstorm for a longer period of time. A tornado is a violent rotating column of air which is in contact with both the surface of the earth and a Cumulonimbus cloud or in rare cases the base of a Cumulus This occurs as the storm's inflow becomes separated from its rain-cooled outflow. An increasing nocturnal, or overnight, low level jet can increase the severe weather potential by increasing the vertical wind shear through the troposphere. Thunderstorms in an atmosphere with virtually no vertical wind shear weaken as soon as they send out an outflow boundary in all directions, which then quickly cuts off its inflow of relatively warm, moist air and kills the thunderstorm. [14]


Planetary boundary layer

See also: Ekman layer, Ekman spiral, Planetary boundary layer, and Surface layer

The atmospheric effect of surface friction with winds aloft force surface winds to slow and back counterclockwise near the surface of the Earth blowing inward across isobars (lines of equal pressure), when compared to the winds in frictionless flow well above the Earth's surface. In standard boundary-layer theory the effects of viscous Diffusion are usually balanced by convective Inertia. The Ekman spiral refers to a structure of currents or winds near a horizontal boundary in which the flow direction rotates as one moves away from the boundary The planetary boundary layer ( PBL) also known as the atmospheric boundary layer ( ABL) or peplosphere, is the lowest part of the Atmosphere The surface layer is the layer of a turbulent fluid most affected by interaction with a solid surface or the surface separating a gas and a liquid EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 This layer where friction slows and changes the wind is known as the planetary boundary layer, sometimes the Ekman layer, and it is thickest during the day and thinnest at night. Daytime heating thickens the boundary layer as winds at the surface become increasingly mixed with winds aloft due to insolation, or solar heating. Insolation is a measure of Solar radiation energy received on a given surface area in a given time Radiative cooling overnight further enhances wind decoupling between the winds at the surface and the winds above the boundary layer by calming the surface wind which increases wind shear. These wind changes force wind shear between the boundary layer and the wind aloft, and is most emphasized at night. [15]

Effects on flight

Main articles: Aeronautics and Gliding

Gliding
Glider ground launch due to wind shear.
Glider ground launch due to wind shear. Aeronautics (from Greek aero which means air or sky and nautis which means sailor i Gliding is a Recreational activity and competitive Sport in which pilots fly un-powered aircraft known as Gliders or sailplanes

In gliding, wind gradients just above the surface affect the takeoff and landing phases of flight of a glider. Terminology A "glider" is an unpowered Aircraft. The most common types of glider are today used for sporting purposes Wind gradient can have a noticeable effect on ground launches, also known as winch launches or wire launches. Gliding is a Recreational activity and competitive Sport in which pilots fly un-powered aircraft known as Gliders or sailplanes 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. [16]

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. [17]

Wind shear is also a hazard for aircraft making steep turns near the ground. It is a particular problem for gliders which have a relatively long wingspan, which exposes them to a greater wind speed difference for a given bank angle. The wingspan (or just span) of an airplane or a Bird, is the distance from the left wingtip to the right wingtip Flight dynamics is the science of air and space vehicle orientation and control in three dimensions The different airspeed experienced by each wing tip can result in an aerodynamic stall on one wing, causing a loss of control accident. [17][18]

Soaring

Soaring related to wind shear, also called dynamic soaring, is a technique used by soaring birds, like albatrosses, who can maintain flight without wing flapping. Dynamic Soaring is a Gliding technique used to gain Kinetic energy by repeatedly crossing the boundary between air masses of significantly different horizontal This is a list of types of Soaring Birds, which are birds that can maintain flight without wing flapping using rising air currents Albatrosses, of the biological family Diomedeidae, are large Seabirds allied to the procellariids, Storm-petrels and Diving-petrels If the wind shear is of sufficient magnitude, a bird can climb into the wind gradient, trading ground speed for height, while maintaining airspeed. [19] By then turning downwind, and diving through the wind gradient, they can also gain energy. [20]

Impact on passenger aircraft
Effect of wind shear on aircraft trajectory. Note how merely correcting for the initial gust front can have dire consequences.
Effect of wind shear on aircraft trajectory. Note how merely correcting for the initial gust front can have dire consequences.

Strong outflow from thunderstorms causes rapid changes in the three-dimensional wind velocity just above ground level. Initially, this outflow causes a headwind that increases airspeed, which normally causes a pilot to reduce engine power if they are unaware of the wind shear. As the aircraft passes into the region of the downdraft, the localized headwind diminishes, reducing the aircraft's airspeed and increasing its sink rate. Then, when the aircraft passes through the other side of the downdraft, the headwind becomes a tailwind, reducing airspeed further, leaving the aircraft in a low-power, low-speed descent. This can lead to an accident if the aircraft is too low to effect a recovery before ground contact. As the result of the accidents in the 1970s and 1980s, in 1988 the U. S. Federal Aviation Administration mandated that all commercial aircraft have on-board windshear detection systems by 1993. The Federal Aviation Administration ( FAA) is an agency of the United States Department of Transportation with authority to regulate and oversee all aspects of The Airborne wind shear detection and alert system detects and alerts the pilot both visually and aurally of a Wind shear condition Between 1964 and 1985, wind shear directly caused or contributed to 26 major civil transport aircraft accidents in the U. S. that led to 620 deaths and 200 injuries. Since 1995, the number of major civil aircraft accidents caused by wind shear has dropped to approximately one every ten years, due to the mandated on-board detection as well as the addition of Doppler weather radar units on the ground. A weather radar is a type of Radar used to locate precipitation, calculate its motion estimate its type ( Rain (NEXRAD)[21]

Sailing

Wind shear affects sailboats in motion by presenting a different wind speed and direction at different heights along the mast. NEXRAD or Nexrad ( Nex t-Generation Rad ar is a network of 158 high-resolution Doppler Weather radars operated by the National Weather In some cases less is more The purpose of this article is to give an overview The mast of a sailing ship is a tall vertical or near vertical Spar, or arrangement of Spars which supports the Sails Large ships have several masts The effect of low level wind shear can be factored into the selection of sail twist in the sail design, but this can be difficult to predict since wind shear may vary widely in different weather conditions. Sail twist is a phenomenon in Sailing where the head of the Sail is at a different Angle of attack from the foot of the sail in order to change the Sailors may also adjust the trim of the sail to account for low level wind shear, for example using a boom vang. A boom vang (US or kicking strap (UK is a line or piston system on a Sailboat used to exert downward force on the boom and thus control the shape [22]

Sound propagation

See also: Speed of sound

Wind shear can have a pronounced effect upon sound propagation in the lower atmosphere. Sound is a vibration that travels through an elastic medium as a Wave. The audibility of sounds from distant sources, such as thunder or gunshots, is very dependent on the amount of shear. Thunder is the sound made by Lightning. Depending on the nature of the lightning and distance of the listener it can range from a sharp Gunshot is also a British hip hop group A gunshot is the discharge of a Firearm, and the Sound effect thereof Shear can have a pronounced effect upon sound propagation in the lower atmosphere, where waves can be "bent" by refraction phenomenon. Refraction is the change in direction of a Wave due to a change in its Speed. The result of these differing sound levels is key in (noise pollution) considerations, for example from roadway noise and aircraft noise, and must be considered in the design of noise barriers. Noise pollution (or environmental noise) is displeasing human- or machine-created sound that disrupts the activity or balance of human or animal life Roadway noise is the collective sound energy emanating from Motor vehicles In the USA it contributes more to environmental noise exposure than any other noise source and is Aircraft noise is defined as Sound produced by any aircraft or its components during various phases of a flight on the ground while parked such as auxiliary power A noise barrier (also called a soundwall, sound berm, sound barrier, or acoustical barrier) is an exterior structure designed to protect [23] This phenomenon was first applied to the field of noise pollution study in the 1960s, contributing to the design of urban highways as well as noise barriers. Noise pollution (or environmental noise) is displeasing human- or machine-created sound that disrupts the activity or balance of human or animal life A noise barrier (also called a soundwall, sound berm, sound barrier, or acoustical barrier) is an exterior structure designed to protect [24]

Hodograph plot of wind vectors at various heights in the troposphere. Meteorologists can use this plot to evaluate vertical wind shear in weather forecasting. (Source: NOAA)
Hodograph plot of wind vectors at various heights in the troposphere. A hodograph is a diagram that gives a vectorial visual representation of the movement of a body or a fluid Meteorologists can use this plot to evaluate vertical wind shear in weather forecasting. (Source: NOAA)

The speed of sound varies with temperature. The National Oceanic and Atmospheric Administration ( NOAA) is a scientific agency within the United States Department of Commerce focused on the conditions of the Sound is a vibration that travels through an elastic medium as a Wave. Since temperature and sound velocity normally decrease with increasing altitude, sound is refracted upward, away from listeners on the ground, creating an acoustic shadow at some distance from the source. Refraction is the change in direction of a Wave due to a change in its Speed. An acoustic shadow is an area through which sound waves fail to propagate due to topographical obstructions or disruption of the waves via phenomena such as wind currents [25] In the 1862, during the American Civil War Battle of Iuka, an acoustic shadow, believed to have been enhanced by a northeast wind, kept two divisions of Union soldiers out of the battle,[26] because they could not hear the sounds of battle only six miles downwind. Causes of the war See also Origins of the American Civil War, Timeline of events leading to the American Civil War The coexistence of a slave-owning South Background As Confederate General Braxton Bragg moved north from Tennessee into Kentucky in September 1862 Union Maj [27]

Effects on architecture

Wind engineering is a field of engineering devoted to the analysis of wind effects on the natural and built environment. Wind engineering is a field of Structural engineering devoted to the analysis of Wind effects on the natural or Built environment to protect it from possible Engineering is the Discipline and Profession of applying technical and scientific Knowledge and Wind is the flow of Air or other Gases that compose an Atmosphere (including but not limited to the Earth's) The phrase built environment refers to the man-made surroundings that provide the setting for human activity ranging from the large-scale civic surroundings to the personal places It includes strong winds which may cause discomfort as well as extreme winds such as tornadoes, hurricanes and storms which may cause widespread destruction. A tornado is a violent rotating column of air which is in contact with both the surface of the earth and a Cumulonimbus cloud or in rare cases the base of a Cumulus A tropical cyclone is a storm system characterized by a low pressure center and numerous Thunderstorms that produce strong winds and Flooding Wind engineering draws upon meteorology, aerodynamics and a number of specialist engineering disciplines. Meteorology (from Greek grc μετέωρος metéōros, "high in the sky" and grc -λογία -logia) is the Interdisciplinary Engineering is the Discipline and Profession of applying technical and scientific Knowledge and The tools used include climate models, atmospheric boundary layer wind tunnels and numerical models. It involves, among other topics, how wind impacting buildings must be accounted for in engineering. [28]

Wind turbines are affected by wind shear. A wind turbine is a rotating machine which converts the Kinetic energy in Wind into Mechanical energy. Vertical wind-speed profiles result in different wind speeds at the blades nearest to the ground level compared to those at the top of blade travel, and this in turn affects the turbine operation. [29] This low level wind shear can create a large bending moment in the shaft of a two bladed turbine when the blades are vertical. [30] The reduced wind shear over water means shorter and less expensive wind turbine towers can be used in shallow seas. [31]

See also

References

  1. ^ a b c d Integrated Publishing. Air safety is a term encompassing the theory investigation and categorization of flight failures, and the prevention of such failures through regulation as well as through A Low level windshear alert system (LLWAS measures wind speed and direction at remote sensor station sites situated around an airport A Low level windshear alert system (LLWAS measures wind speed and direction at remote sensor station sites situated around an airport Sailing is the art of controlling a Sailing vessel. By changing the Rigging, Rudder and dagger or centre board a Sailor manages the force LOW-LEVEL WIND SHEAR. Retrieved on 2007-11-25. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1034 - Máel Coluim mac Cináeda, King of Scots dies Donnchad, the
  2. ^ FAA. The Federal Aviation Administration ( FAA) is an agency of the United States Department of Transportation with authority to regulate and oversee all aspects of FAA Advisory Circular Pilot Wind Shear Guide. Retrieved on 2007-12-15. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 533 - Byzantine general Belisarius defeats the Vandals, commanded by King Gelimer, at the Battle of
  3. ^ NASA. The National Aeronautics and Space Administration ( NASA, ˈnæsə is an agency of the United States government, responsible for the nation's public space program Wind Shear. Retrieved on 2007-10-09. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 768 - Carloman I and Charlemagne are crowned Kings of The Franks.
  4. ^ BBC. Jet Streams in the UK. Retrieved on 2008-05-08. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 589 - Reccared summons the Third Council of Toledo 1450 - Jack Cade's Rebellion: Kentishmen
  5. ^ M. P. de Villiers and J. van Heerden. Clear air turbulence over South Africa. Retrieved on 2008-05-08. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 589 - Reccared summons the Third Council of Toledo 1450 - Jack Cade's Rebellion: Kentishmen
  6. ^ CLARK T. L. , HALL W. D. , KERR R. M. , MIDDLETON D. , RADKE L. , RALPH F. M. , NEIMAN P. J. , LEVINSON D. Origins of aircraft-damaging clear-air turbulence during the 9 December 1992 Colorado downslope windstorm : Numerical simulations and comparison with observations. Retrieved on 2008-05-08. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 589 - Reccared summons the Third Council of Toledo 1450 - Jack Cade's Rebellion: Kentishmen
  7. ^ National Center for Atmospheric Research. T-REX: Catching the Sierra’s waves and rotors Retrieved on 2006-10-21.
  8. ^ Fujita, T.T. (1985). was a severe storms researcher of the twentieth century Born in Kitakyushu, Fukuoka Prefecture, Japan, he studied at Kyushu Institute of Technology "The Downburst, microburst and macroburst". SMRP Research Paper 210, 122 pp.
  9. ^ David M. Roth. David M Roth is an American Meteorologist who has done studies focusing on Hydrometeorology, Hurricanes and Subtropical cyclones He graduated Hydrometeorological Prediction Center. Unified Surface Analysis Manual. Retrieved on 2006-10-22.
  10. ^ Franklin B. Schwing and Jackson O. Blanton. The Use of Land and Sea Based Wind Data in a Simple Circulation Model. Retrieved on 2007-10-03. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 42 BC - First Battle of Philippi: Triumvirs Mark Antony and Octavian fight an indecisive battle with Caesar's
  11. ^ a b James R. Holton (2004). An Introduction to Dynamic Meteorology. ISBN 0-12-354015-1
  12. ^ University of Illinois. Hurricanes. Retrieved 2006-10-21.
  13. ^ Mcilveen, J. (1992). Fundamentals of Weather and Climate. London: Chapman & Hall, p. 339. ISBN 0412411601.  
  14. ^ University of Illinois. Vertical Wind Shear Retrieved on 2006-10-21.
  15. ^ Glossary of Meteorology. E. Retrieved on 2007-06-03. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 350 - Roman usurper Nepotianus, of the Constantinian dynasty, proclaims himself Roman Emperor, entering
  16. ^ (2003) Glider Flying Handbook. U. S. Government Printing Office, Washington D. C. : U. S. Federal Aviation Administration, p. 7-16. FAA-8083-13_GFH.  
  17. ^ a b Piggott, Derek (1997). Gliding: a Handbook on Soaring Flight. Knauff & Grove, pp. 85-86, 130-132. ISBN 9780960567645.  
  18. ^ Knauff, Thomas (1984). Glider Basics from First Flight to Solo. Thomas Knauff. ISBN 0960567631.  
  19. ^ Alexander, R. (2002). Principles of Animal Locomotion. Princeton: Princeton University Press, p. 206. ISBN 0691086788.  
  20. ^ Alerstam, Thomas (1990). Bird Migration. Cambridge: Cambridge University Press, 275. ISBN 0521448220.  
  21. ^ NASA Langley Air Force Base. Making the Skies Safer From Windshear. Retrieved on 2006-10-22.
  22. ^ Garrett, Ross (1996). The Symmetry of Sailing. Dobbs Ferry: Sheridan House, pp. 97-99. ISBN 1574090003.  
  23. ^ Foss, Rene N. (June 1978). "Ground Plane Wind Shear Interaction on Acoustic Transmission". WA-RD 033. 1. . Washington State Department of Transportation. Retrieved on 2007-05-30. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1416 - The Council of Constance, called by the Emperor Sigismund a supporter of Antipope John XXIII burns Jerome of Prague following
  24. ^ C. Michael Hogan, Analysis of highway noise, Journal of Water, Air, & Soil Pollution, Volume 2, Number 3, Biomedical and Life Sciences and Earth and Environmental Science Issue, Pages 387-392, September, 1973, Springer Verlag, Netherlands ISSN 0049-6979.
  25. ^ Everest, F. (2001). The Master Handbook of Acoustics. New York: McGraw-Hill, pp. 262-263. ISBN 0071360972.  
  26. ^ Cornwall, Sir (1996). Grant as Military Commander. Barnes & Noble Inc. ISBN 1566199131 pages = p. 92.  
  27. ^ Cozzens, Peter (2006). The Darkest Days of the War: the Battles of Iuka and Corinth. Chapel Hill: The University of North Carolina Press. ISBN 0807857831.  
  28. ^ Professor John Twidell. Wind Engineering. Retrieved on 2007-11-25. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1034 - Máel Coluim mac Cináeda, King of Scots dies Donnchad, the
  29. ^ Heier, Siegfried (2005). Grid Integration of Wind Energy Conversion Systems. Chichester: John Wiley & Sons, p. 45. ISBN 0470868996.  
  30. ^ Harrison, Robert (2001). Large Wind Turbines. Chichester: John Wiley & Sons, p. 30. ISBN 0471494569.  
  31. ^ Lubosny, Zbigniew (2003). Wind Turbine Operation in Electric Power Systems: Advanced Modeling. Berlin: Springer, p. 17. ISBN 354040340X.  

External links

Dictionary

wind shear

-noun

  1. (meteorology, weather) A change of wind speed, direction, and magnitude.
© 2009 citizendia.org; parts available under the terms of GNU Free Documentation License, from http://en.wikipedia.org
 Dapyx Software network: MP3 Explorer | Ebook Manager | Zenithic