航空气象学课后习题.pdf

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1、Thunderstorm hazards:are only encountered in the cloud口 are unlikely under the base of the cloudQ may be encountered some miles from the cloud口 are unlikely near the top of the cloudA microburst associated with a Cb cloud will normally occur from a point m dw ay up in the cloudQ near the base of the

2、 cloud口 only ahead of the surface impact point口 anywhere up to 10 miles ahead of the cloudThe cumulus stage of a TS is characterised by:口 the beginning of preciprtationD updraughts only口 stronger downdraughts than updraughts口 the anvilThe mature stage of a TS is characterised by:the anvil updraughts

3、 onlyQ the beginning of precipitation stronger downdraughts than updraughtsVertical windshear is the change of_(1)wind vector with height,and horizontalwindshear is the change of_(2)wind vector with distanceo 1 vertical 2 horizontalQ 1 horizontal 2 horizontal口 1 horizontal 2 vertical口 1 vertical 2 v

4、erticalWhen the aircraft encounters turbulence it can experience fluctuations in its indicatedairspeed Fluctuations of between 15 and 25 knots would indicate light turbulence bad turbulenceQ moderate turbulence severe turbulenceWhich of the following situations will give the most severe airframe ici

5、ng?口 stratiform clouds in the tropics口 cumuliform clouds in temperate regions口 stratiform clouds in temperate regions口 cumuliform clouds in the tropicsRain ice most commonly occurs behind a cold front below the freezing level口 behind a warm front below the freezing level口 ahead of a cold front above

6、 the freezing levelQ ahead of a warm front above the freezing levelThe ITCZ will normally reach its most northerly point of travel in:The sub-tropical highs are due to an accumulation of air at the_latitudeThe monsoon low of Asia is an important example of:Q a thermal low which forms in summer口 all

7、of the alternatives are correct口 an orographic low which forms in winter口 a tropical depression which forms in summerA cold low:口 deepens at altitude and turns into a high pressure口 weakens at altitude and turns into a high pressureQ deepens at altitude and is more intense than a warm low weakens at

8、 altitude and is less intense that a warm lowA warm occlusion occurs when theQ air ahead of the warm front is colder than the air behind the cold front air behind the cold front is colder than the air ahead of the warm front口 warm front is catching up the cold front口 air ahead of the warm front is w

9、armer than in the warm sectorThe speed of movement for a cold occlusion is:about the same as for the warm frontThe average gradient of the slope of a cold front is:D 1 50口 1 200口 1 150 1:600The average gradient of the slope of a warm front is:a 1 iso 1 200口 1:50 1:600Virga is:口 precipitation from th

10、e anvil of a Cb behind a cold frontD precipitation that doesnt reach the ground the first precipitation to reach the ground ahead of the warm front口 precipitation from St ahead of the warm frontFor an aircraft flying directly towards a warm front from the cold side,the succession ofcloud types to be

11、 expected as the front is approaches is:Ci-Cc-Ac-Ns口 Ac-Cu-Sc-Sta Ci-Cs-As-Ns口 Ci-Cs-As-AcWhat factors associated with the passage of a front would indicate an increased risk ofwindshear?_ Front speed 20 knots or more,small change in wind direction,temperature change+/-口 10俱Front speed 20 knots or m

12、ore,sharp isobar angle temperature difference across thefront+/-10 俱 Front speed 30 knots or more,temperature change+/-10建，shallow isobar angleFront speed 30 knots or more,temperature difference across the front of 5筑 or more,sharp isobar angleIf air transit is heated from below it ends to become mo

13、re口 stable口 none of the alternatives are correcto neutrally stableQ unstableAn air mass is a large volume of air with similar characteristics of:口 pressure and stability口 pressure tendency and dew pointQ temperature and humidity口 relative humidity and pressureLeast reduction in visibility is caused

14、byPrecipitation from Sc is most likely to be口 light showersQ light intermittentRain/hail showers are descnbed as moderate when the amount of precipitation is:D 2 to 10 mm per hour口 4 to 50 mm per hour口 0 5 to 4 mm per hour口 2 to 10 cm per hourPrecipitation falling from Ns is most likely to be口 moder

15、ate drizzle口 heavy hail showersQ moderate continuous rain light snow showersWhich of the following could be the precipitation falling from Cu?Moderate continuous snowQ Snow showers口 Heavy continuous rain Moderate continuous rainFrom which cloud is hail most like to fall?Drizzle is most likely to fal

16、l from:Greatest reduction in visibility is caused by:Frontal fog:is very low frontal stratus口 often forms at cold fronts rather than wam frontsQ forms when frontal rain cools down the air ahead of the front口 is advection fog in the warm sectorSteaming fog occurs in thewinter when very coki air picks

17、 up moisture from,and is heated by relatively warm waterwinter over land when warm and moist air moves in over the cold surfacearctic regions during the summer when warm air from the south moves in over the coldseatropical regions during the day when wet ground is heated by the sunWhen surface visib

18、ility is reduced to 1200 m due to water droplets in suspension,theweather is referred to as:When surface visibility is reduced to 5000 m by dust particles in suspension,the weatheris termed:Fog is defined as visibility reduced to口 1000 m or less due to water vapour in the atmosphereQ below 1000 m du

19、e to water droplets in the atmosphere口 1000 m to 2000 m due to water droplets in the atmosphere口 1000 m or above due to water droplets in the atmosphereCirriform clouds are mainly composed of:water droplets a mixture of water droplets and ice particles口 supercooled water droplets ice particlesThe tw

20、o main families of clouds are cirriform and cumuliform altoform and stratoform口 nimbus and layeredstratiform and cumuliformAltocumulus lenticularis is associated with:instabilrty through a thick layerQ mountain waves口 an area of turbulence immediately behind a mountain range口 a surface inversionThe

21、halo phenomenon is normally caused by a thin layer of stratusQ layer of cirrostratus口 layer of cirrus before a cold front thin layer of cumulusWhich of the following processes within a layer of air may lead to the building ofcumuliform clouds?Q Convection口 Subsidence口 Frontal lifting wrthin stable l

22、ayers口 RadiationA cap cloud will form:口 above a turbulence layer口 around the top of a cumulrform cloudQ because of orographic uplift in a layer with instabilityAdiabatic cooling is said to occur when a parcel of airAn ELR which is absolutely unstable is:4篌 per 1000 ftAn ELR which is absolutely stabl

23、e is口 1 per 1000 ft口 4 俱 per 1000 ft口 2 俱 per 1000 ft口 3 per 1000 ftAn ELR which is conditionally unstable is:4 仪 per 1000 ft 0 5 per 1000 ftH 2 per 1000 ft口 12 per 1000 ftThe SALR in tropical areas is less than that in temperate regions because:a large amount of latent heat is released during conde

24、nsation which reduces the rate ofcoolinga large amount of latent heat is absorbed dunng condensation which reduces the rate ofcooling口 the saturation content in the tropics is lowera small amount of latent heat is released during condensation which increases the rateof coolingWhen a parcel of air as

25、cends it willJ release latent heat when becoming saturated口 be cooled by the value of the environmental lapse rate口 cool faster if it becomes saturated口 expand and become less humki since the surrounding air is cold and dryBoth dry and saturated air will be unstable when:口 ELRDALR ELRSALR口 ELRDALRWh

26、ich of the following formulae is correct for finding the Relative Humidity(RH)?口 RH=Vapour pressure x 1/Saturation vapour pressure x 100%口 RH=Absolute humidity x 100%/Actual humidity口 RH=Saturation content x 100%/Absolute humidityRH=Amount of water vapour present in the air x 100%/Maximum amount of

27、watervapour the air can holdAir that does not contain the maximum amount of water vapour is:Clear air turbulence associated with the polar front jet stream will be foundbelow the tropopause on the warm side of the jetabove the tropopause on the warm side of the jetbelow the tropopause on the cold si

28、de of the jetabove the tropopause on the cold side of the jetThe wind at 10 000 ft is 045715 kt If the thennal wind in the layer 4000 ft to 10 000 ft is 20kt,with cold air to the North the 4000 ft wind is(assume northern hemisphere):The thermal wind speed in the layer from 2000 ft to 7000 ft is 20 k

29、t,with low temperatureto the North-West,tf the 2000 ft W/V is 210720 kt,the wind at 7000 ft is(assume northernhemisphere):Q 215740 kt 310?10 kt 040?35 kt口 170735 ktA Foehn wind flows over a mountain top of 7000 ft.The temperature at the base on thewindward side is 15馍.The cloud base on the windward

30、side is 3000 ft.The cloud baseon the lee side is 6000 ft What is the temperature at the base of the leeward side of themountain?Severe windshear is likely to occur with the passage of a_(1)and windshear thatoccurs with the passage of a _(2)is likely to be less severe 1 vigorous cold front 2 warm fro

31、ntQ 1.vigorous cold front 2 cold front口 1 vigorous warm front 2 cold front口 1.vigorous warm front 2 warm frontLow level windshear may occur in association with which of the following1.Warm fronts2 Cold frontsWhat factors associated with the passage of a front would indicate an increased risk ofwinds

32、hear?口 Fast moving front,temperature change+/-10涣，shallow isobar angleEFast moving front,temperature difference across the front of 5澳 or more,sharp isobarangle口 Slow moving front,small change in wind direction temperature change+/-10演 Slow moving front,sharp isobar angle,temperature difference acro

33、ss the front+/-10彼The depth of the friction layer will be greatest by:day,over the seaday,over the landnight,over the seanight,over the landlb calculate the surface wind at night over the sea,find the 2000 ft wind back it by 10?in direction in the southern hemisphere and reduce the speed by z back i

34、t by 25?in direction in the northern hemisphere and reduce the speed by 二口 back it by 307in direction in the southern hemisphere and reduce the speed byO back it by 157in direction in the northern hemisphere and reduce the speed by 二With an increase in height from the surface to the top of the frict

35、ion layer the wind is likelyto:D back and increase in the southern hemisphere口 veer and decrease in the northern hemisphere口 back and increase in the northern hemisphere口 veer and increase in the southern hemisphereIn the southern hemisphere the 2000 ft wind velocity:The magnitude of the Geostrophic

36、 Force口 decreases with an increase in densityD decreases wrth a decrease in wind speed口 increases with a decrease in wind speed口 decreases with an increases in latitudeRegarding the geostrophic wind at the equator the geostrophic:force does not apply and winds follow pressure gradients from high to

37、low force does not apply and winds are unable to reach beyond light and variable strength口 equation breaks down and the wind follows directions which are not related to theisobars口 equation breaks down and a large pressure gradient is required for the wind to follow theisobarsCoriolis force affects

38、the flow of air from high pressure to low pressure by deflecting it tothe left in the northern hemisphere口 right in the southern hemisphereD right in the northern hemisphere口 right in both hemispheresBuys Ballots law states that if you stand:口 with your back to the wind then the high pressure is on

39、your left in the northernhemispherewrth your back to the wind then the low pressure is on your left in the northernhemisphere口 facing the wind then the high pressure is on your nght in the northern hemisphere with your back to the wind then the low pressure is on your left in both hemispheresThe win

40、d that blows paraltel to straight isobars at 2000 ft is called the:wind gradientD geostrophic wind口 gradient wind cyclostrophic componentWhen the surface wind changes in direction from South to south-westerly,what is thechange of direction?口 It has backed in both hemispheres口 It has backed in the so

41、uthern hemisphere and veered in the northern hemisphere口 It has veered in the southern hemisphere and backed in the northern hemisphereD It has veered in both hemispheresAn aircraft flies over an airfield QNH 988 hPa.at a pressure altitude of 4500 ft If theelevation of the airfield is 125 ft and a c

42、hange in pressure of 1 hPa is equivalent to 29 ft.What is the true height of the aircraft?An aircraft altimeter set at QNH for a specific airport,is expected to give correct indicationof:the elevation of the airport,regardless of temperature口 0 ft,regardless of temperatureQ the elevation of the airp

43、ort,but only in a standard temperature口 Oft,but only in a standard temperatureWhich of the following altimeter settings indicates the airport elevation when landing?Q If QNH of the airport is set as reference口 If QFE of the airport is set as reference口 If QFF of the airport is set as reference At st

44、andard settingThe difference between QNH and QFE at an airport:口 depends on the air pressure as well as the air temperature at the airport口 depends on the(ambient)air temperature at the airport口 depends on the air pressure at the airportQ is always the sameLanding at an airport you have correctly se

45、t QNH 1023 hPa as the reference pressure onyour altimeter The altimeter indicates 1200 ft after landing Suppose that you change thepressure reference to standard setting(1013 hPa)What will your altimeter indicate(use1 hPa=30 ftpFlying at FL40 you reset the altimeter to reference pressure 993 hPa The

46、 altimeter willindicate:3740 ftH 3460 ft 4540 ft 4340 ftThe temperature at an airport,with an elevation of 500 ft,is-10荚 For landing,QNH is setas the reference on the altimeter What does it indicate on landing?Suppose you are flying with a constant attitude on the altimeter and your altimeter settin

47、gis unchanged Which two of the alternatives mentioned below interact to give minimumactual altitude?1 Flying from low air pressure to high2 Flying from high air pressure to low3.Flying from warm air mass to a cold one4 Flying from a cold air mass to a warm oneYour pressure altimeter is set at 1000 h

48、Pa You have been cleared to join the traffic circuitat 2600 ft and the current QNH is 1010 hPa You join the circuit at 2600 ft but forget toreset your altimeter Other aircraft wrth the correct altimeter setting flying at an indicated2600 ft in the circuit will,compared to you,be flying(1 hPa=30 ft)A

49、n aircraft is at an indicated altitude of 7500 ft over A(270 ft AMSL)with the correct QNHof 1030 hPa set on the altimeter The aircraft then flies to B(1060 ft AMSL),maintaining7500 ft with 1030 hPa still set on the altimeter If the QNH at B is 982 hPa and assuming 1hPa=30 ft,the aircrafts height abo

50、ve B isA pressure altimeter can indicate different altitudes depending on the setting With regardto the setting it can generally be said that it indicatesaltitude corresponding to the difference between the reference pressure and thepressure where the instrument isaltitude in the standard atmosphere