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MET-BNC-MODULE10
1.
Precipitation in the form of showers occurs from
a) stratified clouds
b) cirro-type clouds
c) convective clouds
d) clouds containing only ice crystals
2.
A super-cooled droplet is
a) a water droplet that has been frozen during its descent
b) a small particle of water at a temperature below -50°C
c) a droplet still in liquid state at a temperature below 0°C
d) a water droplet that is mainly frozen
3.
Steady precipitation, in contrast to showery precipitation falls from
a) stratiform clouds with severe turbulence
b) stratiform clouds with little or no turbulence
c) convective clouds with little or no turbulence
d) convective clouds with moderate turbulence
4.
The maximum amount of water vapour that the air can contain depends on the
a) stability of the air
b) dewpoint
c) air temperature
d) relative humidity
5.
Convective clouds are formed
a) in stable atmosphere
b) in unstable atmosphere
c) in mid-latitudes only
d) in summer during the day only
6.
Altostratus clouds are classified as
a) convective clouds
b) high level clouds
c) low level clouds
d) medium level clouds
7.
The most effective way to dissipate cloud is by
a) convection
b) a decrease in temperature
c) a decrease in pressure
d) subsidence
8.
A cumulonimbus cloud at mid-latitudes in summer contains
a) only water droplets
b) ice crystals, water droplets and supercooled water droplets
c) ice crystals and water droplets but never supercooled water droplets
d) only ice crystals
9.
Strongly developed cumulus clouds are an indication of
a) the presence of a low level inversion
b) instability in the atmosphere
c) poor surface visibility
d) the presence of warm air aloft
10.
Areas of sinking air are generally cloudless because as air sinks it
a) reaches warmer layers
b) is heated by expansion
c) is heated by compression
d) loses water vapour
11.
The main factor which contributes to the formation of very low clouds ahead of a warm front is the
a) saturation of the warm air by rain falling into it and evaporating
b) warm air moving over a cold surface
c) reduction of outgoing radiation due to clouds
d) saturation of the cold air by rain falling into it and evaporating
12.
Clouds, classified as being low level are considered to have bases from
a) 500 to 1000 FT
b) 100 to 200 FT
c) 1000 to 2000 FT
d) the surface to 6500 FT
13.
Which of the following are medium level clouds ?
a) Altostratus and altocumulus
b) All convective clouds
c) Cirrocumulus and cirrostratus
d) Cumulonimbus
14.
In an unstable layer there are cumuliform clouds. The vertical extent of these clouds depends on the
a) air pressure at the surface
b) pressure at different levels
c) wind direction
d) thickness of the unstable layer
15.
Which of the following phenomena are formed when a moist, stable layer of air is forced to rise against a mountain range ?
a) Showers and thunderstorms
b) Stratified clouds
c) Areas of severe turbulence
d) Inversions
16.
The height of the lifting condensation level is determined by
a) temperature at surface and air pressure
b) wet adiabatic lapse rate and dewpoint at the surface
c) temperature and dewpoint at the surface
d) wind and dewpoint at the surface
17.
Cumulus clouds are an indication for
a) stability
b) the approach of a warm front
c) the approach of a cold front
d) up and downdrafts
18.
What type of cloud is being described ? A generally grey cloud layer with fairly uniform base and uniform appearance, which may give drizzle or snow grains. When the sun is visible through the cloud, the outline is clearly discernible. Sometimes it appears in the form of ragged patches.
a) Nimbostratus
b) Altostratus
c) Cirrostratus
d) Stratus
19.
The presence of altocumulus castellanus indicates
a) strong convection at low height
b) subsidence in a large part of the troposphere
c) instability in the middle troposphere
d) stability in the higher troposphere
20.
The presence of altocumulus lenticularis is an indication of the
a) presence of mountain waves
b) presence of valley winds
c) development of thermal lows
d) risk of orographic thunderstorms
21.
When otherwise calm and clear conditions exist a station on the shore of a large body of water will experience wind
a) from the water in daytime and from the land at night
b) continually from land to water
c) continually from water to the land
d) from the land in daytime and from the water at night
22.
The greater the pressure gradient the
a) further the isobars will be apart and the weaker the wind
b) further the isobars will be apart and the higher the temperature
c) closer the isobars and the lower the temperatures
d) closer the isobars and the stronger the wind
23.
When isobars, for an area in the mid-latitudes on a weather map, are close together, the wind is most likely to be
a) blowing perpendicular to the isobars
b) changing direction rapidly
c) light
d) strong
24.
In the northern hemisphere a pilot flying at 1000 FT/AGL directly towards the centre of a low pressure area, will find the wind blowing from
a) right and behind
b) about 45 degrees to the right of directly ahead
c) left and behind
d) directly ahead
25.
In the northern hemisphere the wind at the surface blows
a) from a low pressure area to a high pressure area
b) counter-clockwise around, and toward the centre of, a low pressure area
c) counter-clockwise around, and away from the centre of, a high pressure area.
d) clockwise around, and away from the centre of, a low pressure area
26.
Wind is caused by
a) friction between the air and the ground
b) the movements of fronts
c) the rotation of the earth
d) horizontal pressure differences
27.
During a descent from 2000 FT above the surface to the surface (no frontal passage, northern hemisphere), the wind normally
a) backs and increases
b) veers and decreases
c) backs and decreases
d) veers and increases
28.
The Foehn wind is a
a) warm anabatic wind
b) cold anabatic wind
c) cold katabatic wind
d) warm katabatic wind
29.
The sea breeze is a wind from the sea
a) occurring only in mid-latitudes and in daytime
b) that reaches up to the tropopause in daytime
c) blowing at night in mid-latitudes
d) occurring only in the lower layers of the atmosphere in daytime
30.
Low level vertical wind shear can be expected during the night
a) in association with radiation inversions
b) and early morning only in summer
c) in unstable atmospheres
d) and early morning only in winter
31.
In an area of converging air
a) clouds can be formed
b) stratified clouds can be dissolved
c) convective clouds can be dissolved
d) clouds can not be formed
32.
You are flying from east to west in the northern hemisphere at the 500 hPa pressure surface. Which of the following statements is correct?
a) If you have a head wind you are gaining altitude
b) If the wind is from the north you are gaining altitude
c) If you have a tail wind you are losing altitude
d) If the wind is from the south you are gaining altitude
33.
Geostrophic wind is the wind when isobars are
a) curved lines and friction is involved.
b) curved lines and no friction is involved
c) straight lines and friction is involved.
d) straight lines and no friction is involved.
34.
Fair weather cumulus often is an indication of
a) smooth flying conditions below the cloud level
b) turbulence at and below the cloud level
c) poor visibility at surface
d) a high risk of thunderstorms
35.
What relationship exists between the wind at 3000 feet and the surface wind?
a) They are practically the same, except when eddies exist, caused by obstacles
b) The surface wind is veered compared to the wind at 3000 feet and is usually weaker.
c) They have the same direction, but the surface wind is weaker, caused by friction
d) The wind at 3000 feet is parallel to the isohypses and the surface wind direction is across the isobars toward the low pressure and the surface wind is weaker.
36.
The wind tends to follow the contour lines (isohypses) above the friction layer because
a) the friction of the air with the earth's surface gives the airflow a diversion perpendicular to the gradient force.
b) contour lines are lines that connect points with the same wind speed in the upper air
c) the coriolis force tends to balance with the horizontal pressure gradient force
d) the coriolis force acts perpendicular on a line that connects high and low pressure system
37.
The wind speed in a system with curved isobars compared to a system with straight isobars is (other conditions being the same)
a) always lower
b) higher if curvature is anticyclonic
c) always higher
d) higher if curvature is cyclonic
38.
Divergence in the upper air results, near the surface, in
a) falling pressure and likely formation of clouds
b) rising pressure and likely formation of clouds
c) rising pressure and likely dissipation of clouds
d) falling pressure and likely dissipation of clouds
39.
The geostrophic wind depends on
a) density, earth's rotation, geographic latitude
b) earth's rotation, geographic latitude, centripetal force
c) geographic latitude, centripetal force, height
d) centripetal force, height, pressure gradient
40.
In a mountain-valley wind circulation, the mountain wind blows
a) at night down from the mountains
b) during the day down from the mountains
c) during the day up from the valley
d) at night up from the valley
41.
Ahead of a warm front (northern hemisphere) the wind direction changes from the surface up to the tropopause. The effect of this change is that the wind
a) veers in the friction layer and veers above the friction layer
b) backs in the friction layer and backs above the friction layer
c) backs in the friction layer and veers above the friction layer
d) veers in the friction layer and backs above the friction layer
42.
The difference between geostrophic wind and gradient wind is caused by
a) slope of pressure surfaces
b) friction
c) horizontal temperature gradients
d) curvature of isobars
43.
The vertical extent of the friction layer depends primarily on
a) stability, wind speed, roughness of surface
b) roughness of surface, temperature, local time
c) temperature, local time, environmental lapse rate
d) wind speed, roughness of surface, temperature
44.
During periods of prolonged clear skies associated with anticyclonic conditions, the
a) surface wind speed tends to be highest during the early afternoon
b) angle between isobars and surface wind direction tends to be greatest in the early afternoon
c) surface wind speed tends to be highest at night
d) wind tends to back from early morning until early afternoon
45.
The Chinook is a
a) downslope wind that occurs particularly at night as air cools along mountain slopes
b) very cold wind with blowing snow
c) warm anabatic wind up the slopes of snowfields or glaciers
d) warm and dry wind that forms as air descends on the leeward side of the Rocky Mountains
46.
The geostrophic wind speed is directly proportional to the
a) density of the air
b) sine of latitude
c) horizontal pressure gradient
d) curvature of isobars
47.
A strong, dry and warm downslope wind, produced by prior enforced ascent of air over hills or mountains is known as a
a) Scirocco
b) Foehn
c) Bora
d) Mistral
48.
A dry, sand- and dust-laden North Easterly wind that blows in winter over large parts of North West Africa is known as a
a) Scirocco
b) Harmattan
c) Khamsin
d) Pampero
49.
Geostrophic wind
a) is perpendicular to the horizontal pressure gradient force
b) always increases with increasing height
c) is directly proportional to the density of the air
d) veers with height if cold air is advected in the northern hemisphere
50.
In a low pressure system the convergence at the surface is caused by
a) centripetal forces
b) the curvature of the isobars
c) frictional forces
d) the inbalance of the horizontal gradient force and the Coriolis force
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