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MET-BNC-MODULE1
1.
How does the height of the tropopause normally vary with latitude in the northern hemisphere ?
a) It increases from south to north.
b) It remains constant throughout the year.
c) It remains constant from north to south.
d) It decreases from south to north.
2.
What, approximately, is the average height of the tropopause over the equator ?
a) 11 km
b) 40 km
c) 16 km
d) 8 km
3.
In which layer is most of the atmospheric humidity concentrated ?
a) Stratosphere.
b) Tropopause.
c) Stratopause.
d) Troposphere.
4.
At FL 180, the air temperature is -35°C.The air density at this level is:
a) Greater than the density of the ISA at FL 180.
b) Less than the density of the ISA at FL 180.
c) Unable to be determined without knowing the QNH.
d) Equal to the density of the ISA at FL 180.
5.
Between mean sea level and a height of 20 km, the lowest temperature in the ICAO Standard Atmosphere (ISA) is:
a) -56.5°C
b) -100°C
c) -44.7°C
d) -273°C
6.
Under what condition does pressure altitude have the same value as density altitude ?
a) At sea level when the temperature is 0°C.
b) At standard temperature.
c) When the altimeter setting is 1013.2 hPa.
d) When the altimeter has no position error.
7.
In the troposphere the decrease of pressure per 100 m increase in height
a) remains constant at all levels.
b) is smaller at higher levels than at lower levels.
c) is greater at higher levels than at lower levels.
d) is in the order of 27 hPa near MSL.
8.
Which FL corresponds with the 200 hPa pressure level ?
a) FL 390.
b) FL 100.
c) FL 50.
d) FL 300.
9.
What is the approximate vertical interval which is equal to a pressure change of 1 hPa at an altitude of 5500 m ?
a) 32 m (105 FT).
b) 15 m (50 FT).
c) 64 m (210 FT).
d) 8 m (27 FT).
10.
In order to calculate QFE from QNH, which of the following must be known ?
a) Elevation of the airfield.
b) Temperature at the airfield.
c) Elevation and the temperature at the airfield.
d) Elevation of the airfield and the temperature at MSL.
11.
What is the dry adiabatic lapse rate ?
a) 1.5°C/1000 FT
b) 3.5°C/1000 FT
c) 2.0°C/1000 FT
d) 3.0°C/1000 FT
12.
A layer is conditionally unstable if the air
a) becomes stable by lifting it.
b) is unstable for saturated air as well as for dry air.
c) is stable for saturated air and unstable for dry air.
d) is unstable for saturated air and stable for dry air.
13.
A parcel of unsaturated air is lifted to just below the condensation level and then returned to its original level. What is the final temperature of the parcel of air?
a) Higher than the starting temperature.
b) It depends upon the QFE.
c) Lower than the starting temperature.
d) The same as the starting temperature.
14.
What is the effect of a strong low level inversion ?
a) It prevents vertical wind shear.
b) It promotes extensive vertical movement of air.
c) It promotes vertical wind shear.
d) It results in good visual conditions near the surface.
15.
The temperature at FL 140 is -12°C. What will the temperature be at FL 110 if the ICAO standard lapse rate is applied ?
a) -9°C.
b) -15°C.
c) -18°C.
d) -6°C.
16.
Which of the following is a common cause of ground or surface temperature inversion ?
a) Heating of the air by subsidence
b) Terrestrial radiation on a clear night with no or very light winds.
c) The movement of colder air under warm air, or the movement of warm air over cold air.
d) Warm air being lifted rapidly aloft, in the vicinity of mountainous terrain.
17.
What positions are connected by isobars on the surface weather chart?
a) Positions with the same air pressure at a given level
b) Positions with the same temperature at a given level
c) Positions with the same relative pressure heights
d) Positions with the same wind velocity at a given level
18.
At which pressure and temperature conditions may you safely assume that the minimum usable flight level at least lies at the same height, as the minimum safe altitude?
a) In a very cold area with a QNH of 1015 hPa
b) At a temperature greater than or equal to that of the ISA and where the QNH is greater than or equal to 1013.25 hPa
c) At a temperature less than or equal to that of the ISA and where the QNH is less than 1013.25 hPa
d) In a cold low pressure region
19.
What is the main cause for the formation of a polar front jet stream?
a) The pressure difference, close to the ground, between a high over the Azores and a low over Iceland
b) The varied elevations of the tropopause in the polar front region
c) The north-south horizontal temperature gradient at the polar front
d) Strong winds in the upper atmosphere
20.
Which jet stream is connected with a surface front system?
a) The polar front jet stream
b) The equatorial jet stream
c) The subtropical jet stream
d) The easterly jet stream
21.
At approximately what flight level is the subtropical jet stream found?
a) FL 400
b) FL 500
c) FL 200
d) FL 300
22.
A parcel of moist but not saturated air rises due to adiabatic effects. Which of the following changes ?
a) Relative humidity
b) Specific humidity
c) Mixing ratio
d) Absolute humidity
23.
In which of the following changes of state is latent heat released ?
a) Solid to liquid
b) Liquid to gas
c) Solid to gas
d) Gas to liquid
24.
How are high level condensation trails formed that are to be found occasionally behind jet aircraft ?
a) Only through unburnt fuel in the exhaust gases
b) In conditions of low humidity, through the particles of soot contained in the exhaust gases
c) Through a decrease in pressure, and the associated adiabatic drop in temperature at the wing tips while flying through relatively warm but humid air
d) Through water vapour released during fuel combustion
25.
What is the boundary layer between troposphere and stratosphere called?
a) Ionosphere.
b) Tropopause.
c) Atmosphere.
d) Stratosphere.
26.
Which constant pressure altitude chart is standard for FL50?
a) 500 hPa.
b) 700 hPa.
c) 850 hPa.
d) 300 hPa.
27.
Convective activity over land in mid-latitudes is greatest in
a) winter during the night and early morning.
b) summer in the afternoon.
c) summer during the night and early morning.
d) winter in the afternoon.
28.
Which of the following is a possible consequence of subsidence?
a) An inversion over a large area with haze, mist.
b) Clear air turbulence at higher altitudes .
c) Wide spread NS and AS clouds and intense precipitation.
d) CB-clouds and thunderstorms over a large area.
29.
The polar front is the boundary between:
a) polar air and tropical air.
b) arctic air and tropical air.
c) arctic air and polar air.
d) maritime polar air and continental polar air.
30.
What does dewpoint mean?
a) The temperature at which the relative humidity and saturation vapour pressure are the same.
b) The temperature at which ice melts.
c) The freezing level (danger of icing).
d) The temperature to which a mass of air must be cooled in order to reach saturation.
31.
Which of the following is the definition of relative humidity ?
a) Ratio between water vapour pressure and atmospheric pressure X 100
b) Ratio between the actual mixing ratio and the saturation mixing ratio X 100
c) Ratio between water vapour (g) and air (kg) X 100
d) Ratio between air temperature and dewpoint temperature X 100
32.
The relative humidity of a sample air mass is 50%. How is the relative humidity of this air mass influenced by changes of the amount of water vapour in it?
a) It decreases with increasing water vapour.
b) It is not influenced by changing water vapour.
c) It increases with increasing water vapour.
d) It is only influenced by temperature.
33.
Relative humidity
a) does not change when water vapour is added provided the temperature of the air remains constant.
b) changes when water vapour is added, even though the temperature remains constant.
c) is not affected by temperature changes of the air.
d) is not affected when air is ascending or descending.
34.
How, if at all, is the relative humidity of an unsaturated air mass influenced by temperature changes?
a) It decreases with increasing temperature.
b) It is only influenced by the amount of water vapour.
c) It is not influenced by temperature changes.
d) It increases with increasing temperature.
35.
How does relative humidity and the dewpoint in an unsaturated air mass change with varying temperature?
a) When temperature increases, the relative humidity decreases, and the dewpoint remains constant.
b) When temperature decreases, the relative humidity decreases, and the dewpoint increases.
c) When temperature decreases, the relative humidity and the dewpoint remain constant.
d) When temperature increases, the relative humidity increases, and the dewpoint decreases.
36.
When a given mass of air descends, what effect will it have on relative humidity?
a) It increases up to 100%, then remains stable.
b) It remains constant.
c) It decreases.
d) It increases.
37.
During the late afternoon an air temperature of +12°C and a dew point of +5°C were measured. What temperature change must at least occur during the night in order to induce saturation?
a) It must decrease to +6°C.
b) It must decrease to +7°C.
c) It must decrease to +5°C.
d) It must decrease by 5°C.
38.
Which of the following changes of state is known as sublimation (in meteorology)?
a) Liquid direct to vapour
b) Solid direct to liquid
c) Solid direct to vapour
d) Liquid direct to solid
39.
Clouds, fog or dew will always be formed when:
a) water vapour is present.
b) temperature and dew point are nearly equal.
c) water vapour condenses.
d) relative humidity reaches 98%.
40.
Which of the following are favourable conditions for the formation of freezing rain?
a) Water droplets falling from cold air aloft with a temperature below 0°C into air with a temperature above 0°C.
b) Cold air aloft from which hail is falling into air that is warm.
c) An isothermal layer aloft with a temperature just above 0°C through which rain is falling.
d) Warm air aloft from which rain is falling into air with a temperature below 0°C.
41.
Which form of precipitation from clouds containing only water is most likely to fall in mid-latitudes?
a) Heavy rain with large drops.
b) Drizzle.
c) Moderate rain with large drops.
d) Hail.
42.
Which of the following zones is most likely to encounter little or no precipitation?
a) Frontal zones.
b) The north side of the alps with a prevailing Foehn from the south.
c) Occlusions.
d) The north side of the alps with a prevailing Foehn from the north.
43.
Which of the following is a cause of stratus forming over flat land?
a) The release of latent heat.
b) Unstable air.
c) Convection during the day.
d) Radiation during the night from the earth surface in moderate wind.
44.
Which of the following processes within a layer of air may lead to the building of CU and CB clouds?
a) Frontal lifting within stable layers.
b) Radiation.
c) Convection.
d) Subsidence.
45.
What are the characteristics of cumuliform clouds?
a) Large water droplets, stability, no turbulence, showers and mainly rime ice.
b) Small water droplets, stability, no turbulence and extensive areas of rain.
c) Large water droplets, instability, turbulence, showers and mainly clear ice.
d) Small water droplets, instability, turbulence, extensive areas of rain and rime ice.
46.
Which of the following types of clouds are evidence of unstable air conditions?
a) ST, CS.
b) CU, CB.
c) CI, SC.
d) SC, NS.
47.
Which of the following clouds are classified as medium level clouds in temperate regions ?
a) CI, CC.
b) SC, NS
c) CS, ST.
d) AS, AC.
48.
What is the main composition of clouds classified as "high level clouds"?
a) Ice crystals.
b) Water vapour.
c) Water droplets.
d) Supercooled water droplets.
49.
A plain in Western Europe with an average elevation of 500 m (1600 FT) above sea level is covered with a uniform AC layer of cloud during the summer months. At what height above the ground is the base of this cloud to be expected?
a) 15000 - 25000 FT above the terrain.
b) 7000 - 15000 FT above the terrain.
c) 1500 - 7000 FT above the terrain.
d) 100 - 1500 FT above the terrain.
50.
Which of the following clouds may extend into more than one layer?
a) Stratus.
b) Nimbostratus.
c) Altocumulus.
d) Cirrus.
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