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MET-BNC-MODULE14
1.
In which of the following situations is an aircraft most susceptible to icing ?
a) Level flight in snowfall below a nimbostratus layer.
b) Flying in dense cirrus clouds.
c) Level flight below a rain producing cloud when OAT is below zero degrees C.
d) Flying in heavy drizzle.
2.
Which of the following cloud types are most likely to produce light to moderate icing when they are not subject to orographic lifting and consist of supercooled cloud droplets?
a) Stratocumulus and cirrostratus
b) Stratus and cumulonimbus
c) Altocumulus and altostratus.
d) Altostratus and cirrocumulus
3.
A winter day in northern Europe with a thick layer of stratocumulus clouds and temperature close to zero degrees C at ground level, you can expect:
a) Turbulence due to a strong inversion, but no icing because clouds consist of ice crystals
b) Decreasing visibility due to snowfall below cloud base, but only light icing in clouds.
c) A high probability for icing in clouds. Severe icing may occur in the upper part due to accumulation of large droplets.
d) Reduced visibility and light icing in clouds
4.
Which one of the following statements concerning the formation of aircraft icing is most correct ?
a) A cloud consisting of both supercooled water droplets and ice crystals produces aircraft icing
b) Risk for icing increases when cloud temperature decreases well below minus 12 degrees C.
c) Greatest risk of icing conditions is experienced in cirrus clouds.
d) Probability of icing increases when dry snow starts to fall from a cloud.
5.
Which of the following factors have the greatest effect on the formation of the various types of ice on an aircraft ?
a) Cloud temperature and droplet size
b) Aircraft speed and curvature of the airfoil
c) Relative humidity inside the cloud
d) Aircraft speed and size of cloud droplets
6.
Hoar frost is most likely to form when
a) flying inside convective clouds.
b) flying inside stratiform clouds.
c) taking off from an airfield with a significant ground inversion (sky clear).
d) flying in supercooled drizzle.
7.
Two aircraft, one with a sharp wing profile (S), and the other with a thick profile (T), are flying through the same cloud with same true airspeed. The cloud consists of small supercooled droplets. Which of the following statements is most correct concerning ice accretion ?
a) Neither of the aircraft accumulate ice due to the small size of droplets.
b) Aircraft T experiences more icing than S.
c) Aircraft S and T experience the same amount of icing
d) Aircraft S experiences more icing than T.
8.
While descending through a cloud cover at high level, a small amount of a white and rough powderlike contamination is detected along the leading edge of the wing. This contamination is called:
a) Clear ice.
b) Frost.
c) Rime ice.
d) Mixed ice.
9.
A small supercooled cloud droplet that collides with an airfoil will most likely
a) travel back over the wing, creating clear ice.
b) freeze immediately and create clear ice.
c) freeze immediately and create rime ice.
d) travel back over the wing, creating rime ice.
10.
What is the name of the northerly, cold and strong wind, that sometimes blows over a certain part of Europe?
a) Mistral.
b) Bora.
c) Foehn.
d) Typhoon.
11.
What are the characteristics of the Bora ?
a) It is a warm and moist, south-westerly wind experienced in the eastern Mediterranean, that usually carries precipitation.
b) It is a dry and hot southerly wind experienced in the Sahara desert, that often carries dust.
c) It is a very cold wind that blows mainly in winter from a north-westerly direction in the Mediterranean
d) It is a cold and very strong wind that blows mainly in winter from a tableland downwards to the Adriatic
12.
The reason for the fact, that the atmospheric pressure of a polar front depression is normally lower in winter than in summer is that
a) the strong winds of the north Atlantic in winter are favourable for the development of lows.
b) the temperature contrasts between arctic and equatorial areas are much greater in winter.
c) the low pressure activity of the sea east of Canada is higher in winter.
d) converging air currents are of greater intensity in winter.
13.
Which one of the following statements is correct concerning the movement of the ITCZ in the region of West Africa?
a) It reaches its maximum southerly position of 5° S in January
b) It oscillates during the year between 10 degrees North and 10 degrees South.
c) It reaches its maximum northerly position of 15° - 20° N in July
d) It oscillates during the year between the Equator and 10 degrees North.
14.
What is the name of the wind or air mass which gives to the main part of India its greatest proportion of precipitation?
a) South-west monsoon.
b) Indian, maritime tropical air mass.
c) South-east trade wind.
d) Winter monsoon.
15.
When and where is an easterly jet stream likely to be encountered ?
a) In winter along the Russian coast facing the Arctic ocean.
b) Throughout the year to the south of the Azorian high.
c) In summer from south-east Asia extending over southern India to central Africa.
d) In summer from the Middle East extending over the southern part of the Mediterranean to southern Spain.
16.
What is the type, intensity and seasonal variation of precipitation in the equatorial region ?
a) Precipitation is generally in the form of showers but continuous rain occurs also. The greatest intensity is in July.
b) Warm fronts are common with continuous rain. The frequency is the same throughout the year
c) Showers of rain or hail occur throughout the year; the frequency is highest in January.
d) Rainshowers, hail showers and thunderstorms occur the whole year, but frequency is highest during two periods: April-May and October-November.
17.
A flight is to depart from an airport with runways 09 and 27. Surface wind is 270/05; an inversion is reported at 300 feet with turbulence and wind shear. The wind just above the inversion is 090/30. What is the safest departure procedure ?
a) Take-off is not possible under these conditions.
b) Depart on runway 09 with a tailwind.
c) Depart runway 27 with maximum throttle during the passage through the inversion.
d) Depart runway 27 with as steep an ascent as possible.
18.
The turbulence which occurs at high flight levels (above FL 250) is mainly of the type Clear Air Turbulence. In what way can moderate to severe Clear Air Turbulence affect an aircraft, the flight and the passengers?
a) The turbulence is a small scale one and can cause damage. The manoeuvring of the aircraft will be made more difficult or even impossible. For the passengers the flight will be unpleasant.
b) The turbulence is wave like which makes the flight unpleasant for the passengers but the manoeuvring will not be affected essentially.
c) The turbulence can be resembled with the roughness of a washing-board (small scale) and will not have influence on the aircraft and its solidity, but will make flight a little more difficult. The passengers will seldom notice anything of this turbulence.
d) The turbulence is a large scale one (waving) so that the aircraft will be difficult to manoeuvre. The passengers will feel some discomfort.
19.
Aircraft struck by lightning may sometimes get considerable damage and at least temporarily the manoeuvring of the aircraft will be made more difficult. Which one of the following statements is correct?
a) An aircraft has in the atmosphere the same qualities as a "Faradays cage", which means that struck of lightning seldom occurs. But if it happens, the result will be an occasional engine failure. The crew may get a shock.
b) Aircraft made by composite material may get severe damage, the crew may be blinded and temporarily lose the hearing.
c) An aircraft made by metal has a certain capacity to attract a lightning, but the lightning will follow the surface and therefore no damage will be caused.
d) Aircraft made by composite material can't conduct a lightning and will therefore very seldom be struck.
20.
During summer an anticyclone covers the British Isles giving mainly clear skies. At 0600 UTC a south coast airfield in Southern England reports a surface wind of 350/06. The coastline at the airfield perimeter is aligned in an east/west direction. During the next twelve hours the surface wind is likely to
a) back to NW and strengthen by mid-afternoon
b) increase from the north by mid-morning becoming calm towards evening
c) become southerly to south-westerly and increase in velocity by afternoon
d) veer to easterly before becoming calm by the afternoon
21.
During summer, a weak pressure gradient covers a coastal airfield in Eastern England resulting in mainly clear skies. The surface wind at dawn was calm. If the alignment of the coastline in the vicinity of the airfield is predominantly north/south, the surface wind is likely to become
a) easterly and then westerly by afternoon
b) westerly and increase in velocity by afternoon
c) easterly to south-easterly and increase in velocity by afternoon
d) westerly and then southerly by evening
22.
The core of the polar front jet stream is usually located in the
a) polar air above the tropopause
b) polar air below the tropopause
c) tropical air above the tropical tropopause
d) tropical air below the tropopause
23.
Maximum wind speeds associated with subtropical jet streams are usually located in the
a) polar air below the tropopause
b) polar air above the tropopause
c) tropical air above the tropopause
d) tropical air below the tropopause
24.
At which time, if any, are polar front jet streams over the South Pacific usually strongest?
a) October
b) July
c) There is no annual variation
d) January
25.
Which of the following statements concerning the variation in wind speed between summer and winter on the North Atlantic between FL 300 and FL 400 is most correct?
a) The average westerly component is greater in the summer than in the winter. The latitude of the axis of greatest wind speed is also further north in summer than in winter
b) The average westerly component remains the same but the altitude of greatest wind speed reduces in winter
c) The average westerly component remains the same but the axis of greatest speeds moves south in winter
d) The average westerly component is greater in the winter than in the summer. The latitude of the axis of greatest seasonal wind speed is further south in winter than in summer
26.
In summer in the northern hemisphere the maximum wind speeds associated with sub-tropical jet streams are usually located
a) above the tropopause at about 250 hPa
b) above the tropopause at about 100 hPa
c) below the tropopause at about 200 hPa
d) below the tropopause at about 300 hPa
27.
The term PROB as used in a TAF message, indicates the probability in percentage, of phenomena described during a specific period. The numerical values immediately following the term PROB, are:
a) 20 or 30
b) 25 or 35
c) 30 or 40
d) 35 or 50
28.
Isotachs are lines joining equal
a) sea-level pressures
b) wind speed lapse rates
c) wind speeds
d) horizontal wind speed gradients
29.
The visibility transmitted in a METAR is
a) measured by an observer counting the number of lights visible on the runway.
b) the lowest observed in a 360° scan from the meteorological station.
c) given by transmissometer when the visibility is below 1500 metres.
d) the maximum determined by a meteorologist in a 360° scan at the horizon.
30.
Around Paris on January 3rd at 1800 UTC, the surface temperature, under shelter, is +3°C. The sky is covered by 8 oktas of stratus. QNH is 1033 hPa. If the sky is covered all night, the minimum temperature of the night of January 3rd to January 4th should be
a) significantly below 0°C.
b) slightly above +3°C.
c) slightly below +3°C.
d) significantly above +3°C.
31.
On a clear sky, continental ground surface, wind calm, the minimum temperature is reached approximately
a) half an hour after sunrise
b) at the moment the sun rises
c) one hour before sunrise
d) half an hour before sunrise
32.
An isohypse (contour)
a) indicates the altitude of the zero degree isotherm
b) is the limit between two air masses of different temperature
c) indicates the true altitude of a pressure level
d) is the longest slope line of a frontal surface
33.
In relation to the total weight of the atmosphere, the weight of the atmosphere between mean sea level and a height of 5500 m is
a) 99%
b) 50%
c) 1%
d) 25%
34.
Considering the North Atlantic area north of 60°N during winter, the mean height of the tropopause is approximately
a) 56 000 FT
b) 37 000 FT
c) 29 000 FT
d) 20 000 FT
35.
Considering the North Atlantic at latitude 50°N during winter, the mean height of the tropopause is approximately
a) 31 000 FT
b) 43 000 FT
c) 54 000 FT
d) 23 000 FT
36.
Which is true of the temperature at the tropopause?
a) It is higher in polar regions than in equatorial regions
b) It is higher in equatorial regions than in polar regions
c) It is highest in mid-latitudes
d) There is no significant difference with change of latitude
37.
The value of the saturated adiabatic lapse rate is closest to that of the dry adiabatic lapse rate in
a) cumulus
b) stratus
c) freezing fog
d) cirrus
38.
Absolute instability is said to exist whenever the environmental lapse rate
a) is between the dry and saturated adiabatic lapse rate
b) is less than the saturated adiabatic lapse rate
c) exceeds the dry adiabatic lapse rate
d) is less than the dry adiabatic lapse rate
39.
Absolute instability in the atmosphere will occur when the environmental lapse rate is
a) greater than both saturated adiabatic lapse rate and dry adiabatic lapse rate
b) less than saturated adiabatic lapse rate
c) greater than saturated adiabatic lapse rate but less than dry adiabatic lapse rate
d) less than both saturated adiabatic lapse rate and dry adiabatic lapse rate
40.
For both saturated and unsaturated air instability will occur when the
a) environmental lapse rate is greater than saturated adiabatic lapse rate but less than dry adiabatic lapse rate
b) dry adiabatic lapse rate is less than saturated adiabatic lapse rate but greater than environmental lapse rate
c) environmental lapse rate is less than both dry adiabatic lapse rate and saturated adiabatic lapse rate
d) environmental lapse rate is greater than both dry adiabatic lapse rate and saturated adiabatic lapse rate
41.
In the lower levels of the atmosphere when the environmental lapse rate is greater than saturated adiabatic lapse rate but less than dry adiabatic lapse rate - the air mass is described as being
a) unstable
b) absolutely unstable
c) stable
d) conditionally unstable
42.
Surface-based temperature inversions are common during
a) cloudy days in summer when the ground is wet
b) cloud-free days in summer when the ground is dry
c) cloud-free nights in winter when the ground is dry
d) cloudy days in winter when the ground is wet
43.
For a similar pressure gradient, the geostrophic wind speed will be
a) greater at 60°N than at 30°N
b) greater at 30°N than at 60°N
c) the same at all latitudes north or south of 15°
d) equivalent to gradient wind ± thermal component
44.
For the same pressure gradient at 60°N, 50°N and 40°N the speed of the geostrophic wind will be
a) the same at all latitudes
b) greatest at 60°N
c) least at 50°N
d) greatest at 40°N
45.
Under anticyclone conditions in the northern hemisphere, with curved isobars the speed of the gradient wind is
a) less than the geostrophic wind
b) proportional only to the Coriolis force
c) the same as the thermal component
d) greater than the geostrophic wind
46.
In which of the following areas do surface high pressure systems usually predominate over the North Atlantic region between 30°N and 65°N and the adjoining land areas during the northern summer?
a) Iceland, SW USA, Azores
b) Greenland, SW Europe, NE Canada
c) Azores, SE USA, SW Europe
d) Greenland, Azores, NE Canada
47.
In the northern hemisphere the gradient wind of a cyclonic pressure distribution is 350/24, over the sea the surface wind would approximate
a) 340/20
b) 030/28
c) 340/28
d) 030/20
48.
In the northern hemisphere with an anticyclonic pressure system the geostrophic wind at 2000 FT over the sea is 060/15. At the same position the surface wind is most likely to be
a) 075/12
b) 060/18
c) 045/12
d) 060/12
49.
In relation to the polar front jet stream, the greatest rate of wind shear is most likely to occur
a) close to the core on the polar side
b) on the tropical side of the core
c) well below the core
d) 5000 FT or more above the core
50.
The conditions most favourable to the formation of mountain waves are
a) wind direction parallel to the mountain range - wind speed increasing with height - extensive isothermal layer between mountain crests and the tropopause
b) wind speed less than 15 kt and wind direction at right angles to mountains - intense radiation cooling at night particularly at the higher levels
c) wind direction approximately at right angles to the mountain range - wind speed 30 kt and steadily increasing with height - an inversion just above the crest level with less stable air above and below
d) wind direction parallel to the general alignment of the mountain range - wind speed increasing with height - intense surface heating
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