In a land and sea breeze circulation the land breeze blows ?
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A high pressure area slack pressure gradient covers part of the Mediterranean Sea and coastal region during the summer What surface wind direction is likely at an airport at the coast on a sunny ?
A mountain breeze katabatic wind blows ?
Generally northern hemisphere winds at 5000 ft/agl are south westerly while most of surface winds are southerly what the primary reason of difference between these two wind directions Friction between wind the surface. at low elevations friction will slow air hence coriolis force will be less effective in its deflection of wind as elevation decreases direction backs (changes direction in an counter clockwise motion) in northern hemisphere at mid latitude over land wind speed in friction layer decrease 50% angle between wind direction isobars changes 30° (value to be used in examinations). 
Friction between air and ground results in northern hemisphere in Backing of wind decrease of wind speed at surface. at low elevations friction will slow air hence coriolis force will be less effective in its deflection of wind as elevation decreases direction backs (changes direction in an counter clockwise motion) in northern hemisphere at mid latitude over land wind speed in friction layer decrease 50% angle between wind direction isobars changes 30° (value to be used in examinations). 
What degree of turbulence if any likely to be encountered while flying through a cold front in summer over central europe at fl 100 Severe turbulence in cb cloud. at low elevations friction will slow air hence coriolis force will be less effective in its deflection of wind as elevation decreases direction backs (changes direction in an counter clockwise motion) in northern hemisphere at mid latitude over land wind speed in friction layer decrease 50% angle between wind direction isobars changes 30° (value to be used in examinations). 
You are flying at 2500 ft/agl above ground level wind 180° and intend to land at an airport at sea level directly below from approximately which direction would you expect surface wind mid latitude northern hemisphere Severe turbulence in cb cloud. at low elevations friction will slow air hence coriolis force will be less effective in its deflection of wind in northern hemisphere at mid latitude over land wind speed in friction layer decrease 50% wind in friction layer blows across isobars towards low pressure angle between wind direction isobars changes 30° (value to be used in examinations) at 2500 ft you will be out of friction layer on ground direction will be 180° 30° = 150° (south southeast direction) in northern hemisphere friction layer decreases wind direction anti clockwise. Question 126-8
What units are used to report vertical wind shear Severe turbulence in cb cloud. at low elevations friction will slow air hence coriolis force will be less effective in its deflection of wind in northern hemisphere at mid latitude over land wind speed in friction layer decrease 50% wind in friction layer blows across isobars towards low pressure angle between wind direction isobars changes 30° (value to be used in examinations) at 2500 ft you will be out of friction layer on ground direction will be 180° 30° = 150° (south southeast direction) in northern hemisphere friction layer decreases wind direction anti clockwise. Question 126-9
What name given to jet stream lying across india a 262 Severe turbulence in cb cloud. tropical jet stream = tropical easterly jet = equatorial jet stream = only one blowing from east to west during summer season . Question 126-10
An aircraft flying through polar front jet stream from south to north beneath core how would oat change in northern hemisphere during this portion of flight Severe turbulence in cb cloud. the polar front jet stream runs from west to east it will be found in warm air of ferrel cell (sub tropical air mass) if you cross below jet stream (northern hemisphere) you are flying from south to north then you are flying from warm subtropical air into colder polar air the outside air temperature (oat) will decrease. Question 126-11
What the average height of arctic jet stream core Severe turbulence in cb cloud. average height of arctic jet 20000 ft average height of polar front jet 30000 ft the artic jet at a higher latitude than polar front jet hence at a lower height (tropopause lower at poles than equator) arctic jet stream = 20000 ft polar front jet stream = 30000 ft subtropical jet stream = 40000 ft. Question 126-12
What the approximate ratio between height and width a jet stream cross section Severe turbulence in cb cloud. for examination purposes we assume a jet stream to be about 2000 nm long 200 nm wide 2 nm deep this gives an approximate ratio between height width of 1/100. Question 126-13
Which jet stream blows all year round over northern hemisphere The subtropical jet stream. the subtropical polar front jets are present throughout year the polar night jet only active during winter months of northern hemisphere is located at 60° north the equatorial jet only present during northern hemisphere summer. Question 126-14
What the average height of jet core within a polar front jet stream The subtropical jet stream. arctic jet stream = 20000 ft polar front jet stream = 30000 ft subtropical jet stream = 40000 ft . Question 126-15
An aircraft flying from south to north above polar front jet stream at fl 400 in southern hemisphere what change if any in temperature will be experienced The subtropical jet stream. flying from south to north in southern hemisphere means that on crossing polar front aircraft will go from cold air mass (polar maritime) to warm air mass (tropical maritime) at fl400 aircraft will be above tropopause the tropopause in warm air will be higher colder than tropopause in cold air so aircraft will note a decrease in temperature. Question 126-16
A wind speed of 350 kt within a jet stream core should be world wide regarded as Possible but a very rare phenomenon. the highest recorded jet stream speed 354 kt (656 km/h) above isle of south uist (scotland) 13th december 1967 the jet stream varies from about 80 to 350 nm) wide 1 to 3 nm thick its strongest winds are generally encountered at about 30000 feet jet stream winds usually have a speed of 130 to 260 kt. Question 126-17
An aircraft over western europe crossing a jet stream 2500 ft below its core at right angles while crossing outside temperature increasing the prevailing wind Possible but a very rare phenomenon. if outside temperature increasing while crossing below its core it's because you are flying from cold sector to warm sector the wind comes from your right because if you stand with your back to wind in northern hemisphere low pressure low temperature are on your left. Question 126-18
What the main cause the formation of a polar front jet stream The north south horizontal temperature gradient at polar front. fundamental to formation of polar front jet stream the physical property that warm air less dense than cold air when both are at same pressure the polar front represents boundary between higher latitude cold air lower latitude warm air this temperature contrast extends from earth's surface up to polar front jet stream altitude air pressure determined the weight of overlying air in vicinity of polar front air pressure drops more rapidly with an increase in altitude in more dense cold air than in less dense warm air the effect of temperature on air density results in air pressure at any given altitude being higher on warm (equatorward) side of polar front than on cold (poleward) side when cold warm air reside side side higher altitude greater pressure difference between cold warm air at same altitude across polar front at upper levels (including jet stream altitude) horizontal pressure differences cause air to flow from warm air side of front towards cold air side of front once air in motion it deflected earth's rotation (coriolis effect) upper level air flowing poleward from higher pressure towards lower pressure deflected to right in northern hemisphere (or to left in southern hemisphere) the result a jet stream flowing generally towards east parallel to above polar front. Question 126-19
Which jet stream connected with a surface front system The polar front jet stream. the polar front the boundary between polar air tropical air you can see that polar front jet stream connected with polar front for other jetstreams there no front (for information easterly jet stream the equatorial jetstream). Question 126-20
At approximately what flight level the subtropical jet stream found The polar front jet stream. jet streams vary in height from 20000 ft to 40000 ft can reach speeds of more than 240 kt the subtropical jet stream located around 30°n the subtropical jet stream can be found at fl400 (40000 ft) arctic jet stream = 20000 ft polar front jet stream = 30000 ft subtropical jet stream = 40000 ft. Question 126-21
Flight zurich to rome etd 1600 utc eta 1800 utc at what flight level would you first expect to encounter clear air turbulence on climb out from zurich 273 The polar front jet stream. cat area n°2 shows moderate cat between fl220 fl400. Question 126-22
At what flight level the jet stream core that situated over northern scandinavia 274 The polar front jet stream. the jet stream flight level indicated below his position maximum jet stream wind speed 135 kt. Question 126-23
Select from map wind the route zurich london at fl 280 277 The polar front jet stream. 225°/95 kt 220°/55 kt 210°/40 kt 255°/35 kt average wind 227°/56 kt in northern hemisphere wind turns clockwise with height speed increases it means that normally at fl280 (chart for fl300) we should expect a wind of 220°/50 kt anyway answer 220/60 remains only valid answer. Question 126-24
What name given to jet stream lying over north africa b 280 Sub tropical jet stream. the subtropical jet stream located around 30°n/s . Question 126-25
What wind forecast at fl 390 over paris 281 Sub tropical jet stream. the wind blowing with a south south west component west of paris speed reducing (from 45 kt to 30 kt close to luxembourg) '210°/40 kt' the correct answer. Question 126-26
What the direction and maximum speed of jet stream affecting route between munich and london 285 Sub tropical jet stream. . Question 126-27
Flight from bordeaux to amsterdam eta 2100 utc at eta amsterdam what surface wind forecast taf eham 281500z 281601 14010kt 6000 ra sct025 becmg 1618 12015g25kt sct008 bkn013 tempo 1823 3000 ra bkn005 ovc010 becmg 2301 25020kt 8000 nsw bkn020 = 2 ° / 5 kt gusts 25 kt. becmg (becoming) indicates a change to forecast conditions expected to occur slowly within period designated in time group immediately following heading the duration of this change normally about 2 hours the elements included in becmg line will supercede some of previous taf groups but it possible all groups may change any group omitted in becmg line will be same during becmg period as indicated in main taf line in this question wind becoming 120°/15 kt gusts 25 kt (12015g25kt) between 16h 18h it will remain unchanged until 23h then wind becoming 250°/20kt between 23h 01h. Question 126-28
The equatorial easterly jet a jet stream that occurs Only in summer of northern hemisphere at approximately 45 ft. this jet occurs in northern summer between 10°n 20°n chiefly over or just to south of high land masses such as in asia africa its occurrence due to a temperature gradient with colder air to south which produces sufficient temperature differential above 45000 ft to give wind speeds of over 100 kt because colder temperatures at height are to south it an easterly jet (this jet now more usually known as tropical easterly jet perhaps more correctly as it lies some distance from equator . Question 126-29
In which zone of a polar front jet stream the strongest cat to be expected On polar air side of core. the strongest cat in warm tropical air but on cold polar air side of core. Question 126-30
What the minimum speed a wind to be classified as a jet stream On polar air side of core. the heavyline line delineating jet axis begins/ends at points where a wind speed of 40 m/s (80 kt) forecast. Question 126-31
A wind sounding in region of a polar front jet stream gives following windprofile northern hemisphere 900hpa 220/20kt800hpa 220/25kt700hpa 230/35kt500hpa 260/60kt400hpa 280/85kt300hpa 300/100kt250hpa 310/120kt200hpa 310/80ktwhich system the jet stream associated with On polar air side of core. the highest wind speed in core of polar front jet stream at 250 hpa approximately fl340 in northern hemisphere cold front jet from sw the warm front jet from nw at fl340 jet direction 310° it a north west direction. Question 126-32
What the most significant difference between an equatorial jet stream and all other jet streams On polar air side of core. its wind direction from east to west this jet occurs in northern summer between 10°n 20°n chiefly over or just to south of high land masses such as in asia africa because colder temperatures at height are to south it an easterly jet (this jet now more usually known as tropical easterly jet perhaps more correctly as it lies some distance from equator . Question 126-33
You cross a jet stream in horizontal flight at approximately right angles while crossing in spite of a strong wind of 120 kt you notice temperature barely changes which of following statements correct This phenomenon absolutely normal as you are crossing jet core. its wind direction from east to west this jet occurs in northern summer between 10°n 20°n chiefly over or just to south of high land masses such as in asia africa because colder temperatures at height are to south it an easterly jet (this jet now more usually known as tropical easterly jet perhaps more correctly as it lies some distance from equator . Question 126-34
What jet streams are likely to be crossed during a flight from stockholm to rio janeiro 23°s at fl 350 in july A polar front jet stream followed one or two subtropical jet streams. . Question 126-35
While crossing a jet stream at right angles in western europe 3000 ft below its core and oat decreasing what would be prevailing wind A polar front jet stream followed one or two subtropical jet streams. if you are moving to an area of decreasing temperature then you must be moving from an area of warm air to cold in northern hemisphere frontal jetstream which just underneath warm sector tropopause in warm sector close to front blows with cold sector to its left therefore if you are crossing to cold sector jet blowing from left . Question 126-36
During winter months in mid latitudes in northern hemisphere polar front jet stream moves toward South speed increases. in winter polar front moves south during summer it moves north winter speed 130 to 150 kt summer speed 60 to 100 kt. Question 126-37
What causes surface winds to flow across isobars at an angle rather than parallel to isobars South speed increases. friction a force it a force that slows motion dampens energy in meteorology friction important because it causes wind speeds at surface to be less more turbulent than they otherwise would be rough terrain more effective in decreasing wind speed than a water surface friction processes can help promote surface convergence uplift resistance to movement of air flowing along surface of earth induces wind to flow across isobars at an angle. Question 126-38
What prevents air from flowing directly from high pressure areas to low pressure areas South speed increases. pressure gradient tries to move air from high pressure to low pressure but coriolis force deflects it to right in northern hemisphere to left in southern hemisphere. Question 126-39
What the approximate speed of a 25 knot wind expressed in kilometres per hour South speed increases. 1 kt = 1 852 km/h use this formula (25 kt x 2) 10% = 45 km/h. Question 126-40
What the approximate speed of a 90 km/h wind expressed in knots South speed increases. 1 kt = 1 852 km/h use this formula (90 km/h + 10%)/2 = 49 5 kt.
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