wind shear wind shear referred wind gradient difference wind speed direction relatively short distance atmosphere atmospheric wind shear normally described vertical horizontal wind shear vertical wind shear change wind speed direction change altitude horizontal wind shear change wind speed change lateral position given altitude wind shear meteorological phenomenon occurring small distance associated scale weather features lines cold fronts commonly observed near caused thunderstorms fronts areas locally higher low level winds referred low level jets near mountains radiation occur clear skies calm winds buildings wind turbines wind shear significant effect landing aircraft effects control aircraft sole contributing cause aircraft accidents wind shear experienced pedestrians ground level walking plaza tower block suddenly encountering strong wind stream flowing base tower phenomenon concern architects sound movement atmosphere affected wind shear bend wave causing sounds heard normally vice versa strong vertical wind shear tropical cyclone development helps organize individual thunderstorms longer life cycles produce severe weather thermal wind concept explains differences wind speed different heights dependent horizontal temperature differences explains existence jet stream definition wind shear refers variation wind horizontal vertical distances airplane pilots generally regard significant wind shear horizontal change knots light aircraft near knots flight altitude vertical speed changes greater knots qualify significant wind shear aircraft low level wind shear affect aircraft landing disastrous ways pilots trained avoid wind shear loss excess knots rationale additional caution includes intensity double minute winds shift excessive cross wind knots threshold stages low altitude operations historical wind shear accidents involved knot wind shear key factor creation severe thunderstorms additional hazard associated wind shear strongly observed weather situations shear observed include weather fronts significant shear observed temperature difference moves knots faster fronts dimensional phenomena frontal shear observed altitude surface seen horizontally vertically vertical wind shear warm fronts aviation concern near cold fronts greater duration upper level jet streams associated upper level jet streams phenomenon known clear air cat caused vertical horizontal wind shear connected wind gradient edge jet streams cat strongest shear jet usually axis jet low level jet streams nocturnal low level jet forms overnight earth surface ahead cold significant low level vertical wind shear develop near lower portion low level jet known wind shear nearby thunderstorms mountains winds blow mountain vertical shear observed lee flow strong turbulent known associated lee waves form dangerous ascending descending aircraft clear calm night radiation formed near ground friction affect wind layer change wind degrees direction speed nocturnal overnight low level jet observed tends strongest sunrise density differences cause additional problems aviation outflow boundary forms shallow layer rain cooled air spreading near ground level parent thunderstorm speed directional wind shear result leading edge dimensional boundary stronger outflow boundary stronger resultant vertical wind shear horizontal component weather fronts weather fronts boundaries masses air different different temperature moisture properties normally convergence zones wind field principal cause significant weather surface weather analyses depicted colored lines symbols air masses usually differ temperature differ humidity wind shear horizontal occurs near boundaries cold fronts feature narrow bands thunderstorms severe weather preceded lines dry lines cold fronts surface boundaries significant horizontal wind shear warm fronts stationary line separates regions differing wind speed known shear line wind direction normally remains constant tropics tropical waves east west atlantic eastern pacific basins directional speed shear occur axis stronger tropical waves northerly winds wave axis southeast winds seen wave axis horizontal wind shear occur local land breeze sea breeze boundaries near coastlines magnitude winds offshore nearly double wind speed observed onshore attributed differences friction land masses offshore waters directional differences particularly local sea change wind shore daylight hours vertical component thermal wind thermal wind meteorological term referring actual wind difference wind pressure levels formula formula formula essence wind shear present atmosphere horizontal changes temperature ocean horizontal density atmosphere temperature uniform wind independent height stems fact wind flows areas low high temperature manner wind flows areas low high pressure thermal wind equation formula formula height fields formula formula formula upward pointing unit vertical direction thermal wind equation determine wind tropics formula small zero near equator equation reduces stating formula small equation basically describes existence jet stream westerly current air maximum wind speeds close factors important result temperature contrast equator pole effects tropical cyclones tropical cyclones basically heat engines fueled temperature gradient warm tropical ocean surface colder upper atmosphere tropical cyclone development requires relatively low values vertical wind shear warm core remain surface circulation center promoting strengthening vertical wind shear tears machinery heat engine causing break strongly tropical cyclones weaken upper circulation blown away low level center vertical wind shear tropical cyclone environment important wind shear weak storms cyclone grow vertically heat released air directly storm aiding development stronger wind shear means storms heat release dispersed larger area effects thunderstorms severe weather severe thunderstorms spawn tornadoes require wind shear organize storm way maintain thunderstorm longer period time occurs storm separated rain cooled outflow increasing nocturnal overnight low level jet increase severe weather potential increasing vertical wind shear thunderstorms atmosphere virtually vertical wind shear weaken soon send outflow boundary directions quickly cuts relatively warm moist air kills thunderstorm boundary layer atmospheric effect surface friction winds aloft force surface winds slow near surface earth blowing inward lines equal pressure compared winds flow earth surface layer friction changes wind known boundary layer layer day night daytime heating boundary layer winds surface increasingly mixed winds aloft solar heating cooling overnight wind winds surface winds boundary layer surface wind increases wind shear wind changes force wind shear boundary layer wind aloft emphasized night effects flight wind surface affect takeoff landing phases flight wind gradient noticeable effect ground launches known launches wire launches wind gradient significant sudden pilot maintains pitch attitude indicated increase possibly exceeding maximum ground launch tow speed pilot adjust deal effect gradient landing wind shear hazard particularly winds strong descends wind gradient final approach landing decreases sink rate increases insufficient time accelerate prior ground contact pilot wind gradient use higher approach speed compensate wind shear hazard aircraft making steep turns near ground particular problem relatively long wingspan greater wind speed difference given bank angle different experienced wing tip result aerodynamic stall wing causing loss control accident wind shear wind threat particularly base jumping flying pushed course sudden shifts wind direction speed collided bridges trees ground obstacles routinely adjustments position open compensate changes direction making landings prevent accidents canopy collisions canopy soaring soaring related wind shear called dynamic soaring technique soaring birds like maintain flight wing wind shear sufficient magnitude bird climb wind gradient trading ground speed height maintaining turning diving wind gradient gain energy pilots rare occasions wind shear create wave occurs atmospheric separates layers marked difference wind direction wind encounters layer caused coming create significant shear waves soaring impact passenger aircraft strong outflow thunderstorms causes rapid changes dimensional wind velocity ground level initially outflow causes increases normally causes pilot reduce engine power unaware wind shear aircraft passes region localized reducing aircraft increasing sink rate aircraft passes reducing lift generated wings leaving aircraft low power low speed descent lead accident aircraft low effect recovery ground contact result accidents 1970s 1980s notably following crash flight mandated commercial aircraft board wind shear detection systems wind shear directly caused contributed major civil transport aircraft accidents led deaths injuries number major civil aircraft accidents caused wind shear dropped approximately years mandated board detection addition weather radar units ground installation high resolution terminal weather radar stations airports commonly affected wind shear aided ability pilots ground controllers avoid wind shear conditions sailing wind shear affects motion presenting different wind speed direction different heights mast effect low level wind shear selection sail twist sail design difficult predict wind shear vary widely different weather conditions sailors adjust trim sail account low level wind shear example boom sound propagation wind shear pronounced effect sound propagation lower atmosphere waves bent phenomenon sounds distant sources thunder dependent shear result differing sound levels key noise pollution considerations example roadway noise aircraft noise considered design noise barriers phenomenon applied field noise pollution study 1960s contributing design urban highways noise barriers speed sound varies temperature temperature sound velocity normally decrease increasing altitude sound upward away listeners ground creating acoustic shadow distance source american civil war battle acoustic shadow believed enhanced northeast wind kept divisions union soldiers battle hear sounds battle miles effects architecture wind engineering field engineering devoted analysis wind effects natural built environment includes strong winds cause discomfort extreme winds tornadoes hurricanes storms cause widespread destruction wind engineering draws number specialist engineering disciplines tools include climate models atmospheric boundary layer wind tunnels numerical models involves topics wind buildings accounted engineering wind turbines affected wind shear vertical wind speed profiles result different wind speeds blades nearest ground level compared blade travel turn affects turbine operation low level wind shear create large bending moment shaft bladed turbine blades vertical reduced wind shear water means shorter expensive wind turbine towers shallow seas
Wind shear