jet stream jet streams fast flowing narrow air currents found upper atmosphere planets including earth main jet streams located near altitude major jet streams earth westerly winds flowing west east paths typically shape jet streams start stop split parts combine stream flow directions including opposite direction remainder jet strongest jet streams polar jets sea level higher altitude somewhat weaker subtropical jets polar jet subtropical jet northern hemisphere polar jet flows middle northern latitudes north_america europe asia intervening oceans southern hemisphere polar jet circles antarctica year round jet streams product factors atmospheric heating solar radiation produces large scale polar circulation cells action force acting moving masses force caused planet rotation axis planets internal heat drives jet streams polar jet stream forms near interface polar circulation cells subtropical jet forms near boundary circulation cells jet streams exist summer easterly jets form tropical regions typically dry air encounters humid air high altitudes low level jets typical regions central united_states use location jet streams aid weather main commercial relevance jet streams air travel flight time dramatically affected flying flow clear air potential hazard aircraft passenger safety found jet stream vicinity create substantial alteration flight times discovery eruption volcano weather tracked mapped effects sky years labelled phenomenon smoke stream 1920s japanese detected jet stream site near tracked pilot balloons known balloons determine upper level winds rose atmosphere work largely went unnoticed outside japan published american pilot man fly world solo given credit discovery jet streams post invented suit let fly metres year death post attempts high altitude flight noticed times ground speed greatly exceeded air speed german credited special term literally jet current phenomenon modern german usage sources credit real understanding nature jet streams regular repeated flight path world war consistently noticed westerly excess mph flights example similarly team american guam including observations forecast high west winds slow bombers going japan description polar jet streams typically located near hpa atmosphere pressure level kilometres sea level weaker subtropical jet streams higher kilometres jet streams dramatically large changes altitude jet streams form near breaks transitions polar circulation cells circulation force acting masses drives jet streams polar jets lower altitude mid latitudes strongly affects weather aviation polar jet stream commonly found latitudes closer subtropical jet streams located close latitude northern polar jet stream said follow sun slowly northward hemisphere southward hemisphere width jet stream typically kilometres miles vertical thickness kilometres jet streams typically continuous long distances common path jet typically shape eastward lower speeds actual wind flow large wave jet stream known wave wave waves caused changes effect latitude smaller scale waves superimposed waves scale kilometres long flow pattern large scale ridges waves jet streams split encounters upper level low portion jet stream base remainder jet moves north wind speeds greatest temperature differences gradient air masses greatest exceed mph mph measured jet stream moves west east bringing changes weather understand path jet streams cyclonic storm systems lower levels atmosphere knowledge course important weather example britain experienced severe flooding result polar jet staying south summer polar subtropical jets merge locations times times separated cause general winds strongest immediately locally tornadoes tropical cyclones situations air masses different temperatures meet resulting pressure difference caused density difference ultimately causes wind highest transition zone wind flow directly hot cold area effect flows boundary air masses facts consequences thermal wind relation balance forces acting atmospheric air parcel vertical direction primarily force acting mass parcel force difference pressure surfaces parcel forces results acceleration parcel direction upward force exceeds weight downward weight exceeds force balance vertical direction referred tropics dominant forces act horizontal direction primary struggle force pressure gradient force balance forces referred given balance derive thermal wind relation vertical gradient horizontal wind proportional horizontal temperature gradient air masses cold dense north hot dense south separated vertical boundary boundary removed difference result cold air mass slipping dense air mass effect cause moving mass east moving mass west general trend atmosphere temperatures decrease direction result winds develop eastward component component grows altitude strong eastward moving jet streams simple consequence fact equator warmer north south poles polar jet thermal wind relation explain winds organized tight jets distributed broadly hemisphere factor contributes creation concentrated polar jet sub tropical air masses dense polar air masses polar causes surface low pressure higher pressure altitude high altitudes lack friction allows air respond freely steep pressure gradient low pressure high altitude pole results formation wind experience strong considered quasi polar jet stream closely linked process acceleration air flow areas low high pressure respectively link formation cyclones polar relatively narrow region subtropical jet second factor contributes concentrated jet applicable subtropical jet forms limit tropical cell order circulation respect tropical air rises moves sinking cell circulation tends conserve angular momentum friction ground significant air masses begin moving northward eastward force true hemisphere moving air implies increased eastward component winds note southern hemisphere planets atmosphere multiple jet streams caused convection cells form familiar banded color structure convection cells driven internal heating factors control number jet streams atmosphere active area research models increases radius holding parameters fixed number jet streams decreases effects hurricane protection subtropical jet stream rounding base mid oceanic upper trough thought reasons resistant long list hawaii hurricanes approached example approached dissipated reaching landfall cited vertical wind shear evidenced photo uses earth northern polar jet stream important aviation weather stronger lower altitude subtropical jet streams covers countries southern polar jet stream circles antarctica southern tip south_america term jet stream contexts usually implies northern polar jet stream aviation location jet stream extremely important aviation commercial use jet stream began november pan flew tokyo honolulu altitude metres cut trip time hours cut time flight nets fuel savings airline industry north_america time needed fly east continent decreased minutes airplane fly jet stream increased fly west associated jet streams phenomenon known clear air cat caused vertical horizontal wind shear caused jet streams cat strongest cold air jet axis jet clear air cause aircraft present passenger safety hazard caused fatal accidents death passenger flight future power generation scientists investigating ways harness wind energy jet stream according estimate potential wind energy jet stream percent needed meet world current energy needs required technology reportedly years develop major scientific articles jet stream power claim jet streams generate total power climatic impact miller claim jet streams generate total power climatic impact catastrophic aerial attack near end world war japanese fire balloon designed cheap weapon intended use jet stream pacific_ocean reach west coast canada united_states relatively ineffective weapons attacks north_america world war causing deaths small damage changes climate cycles influences average location upper level jet streams leads variations precipitation temperature north_america affecting tropical cyclone development eastern pacific atlantic basins combined impact cold season rainfall europe changes change location jet stream south_america partially affects precipitation distribution continent events increased precipitation expected california southerly storm track portion increased precipitation falls gulf_coast southeast stronger normal southerly polar jet stream snowfall greater average southern sierra nevada mountain range normal states northern tier lower exhibits normal temperatures fall winter gulf coast experiences normal temperatures winter season subtropical jet stream deep tropics enhanced increased convection pacific decreases tropical cyclogenesis atlantic tropics normal increases tropical cyclone activity eastern pacific subtropical jet stream displaced north normal position frontal systems thunderstorm complexes reaching central portions continent north_america increased precipitation diverted pacific_northwest northerly storm track jet stream storm track shifts far northward bring normal conditions form increased snowfall states hot dry summers snowfall normal pacific_northwest western north_atlantic jet stream stronger normal directs stronger systems increased precipitation europe dust bowl evidence suggests jet stream partly responsible widespread drought conditions 1930s dust bowl normally jet stream flows east gulf_of_mexico turns northward pulling moisture dumping rain dust bowl jet stream weakened changed course traveling farther south normal great plains areas midwest rainfall causing extraordinary drought conditions longer term climatic changes climate scientists jet stream gradually weaken result global warming trends arctic sea ice decline reduced snow cover patterns weather expected arctic heat faster parts globe turn reduces temperature gradient drives jet stream winds causing jet stream weaker variable course particularly early jet stream low latitude lying closer english channel usual north scotland latitude found average position jet stream moving northward rate kilometres year north_america type change lead drier conditions southern tier united_states frequent intense tropical cyclones tropics similar slow drift found studying jet stream time frame upper level jets polar night jet polar night jet stream forms winter months nights longer polar nights respective latitude polar night jet moves greater height feet summer dark months air high poles colder air equator difference temperature gives rise extreme air pressure differences combined effect create polar night jets race eastward altitude miles polar vortex polar night jet warmer air edge polar vortex enter vortex cold polar air increasingly cold warmer air lower latitudes energy sun polar night low level jets wind lower levels atmosphere referred jets barrier jet barrier jet low levels forms upstream mountain chains mountains forcing jet oriented parallel mountains mountain barrier increases strength low level wind percent southerly low level jet helps fuel overnight thunderstorm activity warm season normally form convective systems form overnight hours similar phenomenon develops australia pulls moisture cut lows form mainly southwestern portions continent valley exit jet valley exit jet strong valley elevated air current emerges intersection valley adjacent plain winds frequently reach maximum mph height ground surface winds jet sway vegetation significantly weaker likely found valley regions exhibit mountain wind systems dry mountain ranges deep valleys terminate abruptly plain impacted factors gradually shallower distance increases africa mid level african easterly jet occurs summer west_africa nocturnal low level jet occurs great plains east south_africa low level easterly african jet stream considered play crucial role southwest monsoon africa helps form tropical waves tropical atlantic eastern pacific oceans warm season formation thermal low northern africa leads low level westerly jet stream june october
Jet stream