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ATPL Met > Exam revision > Flashcards

Exam revision Flashcards

1
Q

What is the atmosphere broken into?

A

78% Nitrogen
21% Oxygen
1% Other Gases (argon etc)

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2
Q

What layers is the atmosphere?

A 
Troposphere
Tropopause
Stratosphere
Stratopause
Mesosphere
Mesopause
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3
Q

What percentage of the air is water in the troposphere?

A

0 to 5%

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4
Q

What is the lowest portion of the atmosphere?

A

Troposphere

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5
Q

What happens with temperature in troposphere?

A

Decreases with increase in height

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6
Q

Where is the majority of water vapour, clouds and weather found?

A

Troposphere

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7
Q

What is the boundary where temperature no longer decreases with height?

A

Tropopause

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8
Q

What altitude is tropopause at pole and equator?

A

Approx 26500km at temp of -40 over poles

Approx 59500km at temp of -70 at equator

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9
Q

In the lower portions of the stratosphere, what is the temperature? Increasing, decreasing or constant?

A

Constant (aka isothermal layer)

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10
Q

What is the temperature in the upper stratosphere like? Increasing, decreasing or constant?

A

Increases with height due to ozone

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11
Q

What is an inversion?

A

Temperature increases with height

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12
Q

When can an inversion occur in the troposphere?

A

When the lapse rate is negative

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13
Q

What is the ISA ELR?

A

Decrease of temp of 2 degrees (1.98) per 1000 feet

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14
Q

What height is the ISA ELR for?

A

0 to 36090ft AMSL

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15
Q

What is the ISA Mean sea level temp?

A

15 degrees

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16
Q

What is the ISA tropopause temp?

A

-56 degrees

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17
Q

What are the three ways heat can be transferred

A

Radiation
Conduction
Convection

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18
Q

What are isotherms?

A

Lines on weather map joining places having same temperature at particular time

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19
Q

Normally the diural range of temperature is greatest where?

A

An inland location

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20
Q

What is the primary cause of weather?

A

Temperature differential

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21
Q

Radiant energy arriving from the sun is termed?

A

Insolation

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22
Q

What is an isobar?

A

Joins places having same surface pressure at a particular time

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23
Q

What happens to atmospheric pressure with increase in altitude?

A

Decreases

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24
Q

At low level, what does pressure reduce at?

A

1Hpa per 30 ft

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25
Q

What does air density depend on?

A

Pressure
Temperature
Humidity

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26
Q

What does a decrease in pressure do to density?

A

Decreases density

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27
Q

What does an increase in temperature do to density?

A

Decreases density

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28
Q

What does increase in humidity do to density?

A

Decreases density

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29
Q

What is semidiurnal variation?

A

Rhythmic variation in pressure over 12 hours

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30
Q

What causes semidiurnal variation?

A

Expansion and contraction of atmosphere as it heats and cools

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31
Q

When is the semidiurnal variation greatest?

A

In the tropics

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32
Q

What is local QNH?

A

Set sea level pressure for location

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33
Q

What will setting airfield elevation on main scale do with regards to local QNH

A

Provide approximate QNH

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34
Q

What is area QNH?

A

Predicted average sea level pressure for 3 hour period

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35
Q

When would you use area QNH?

A

Within 100nm when cruising at or below 10000ft

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36
Q

What separates aircraft on standard pressure and on QNH?

A

Transition layer

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37
Q

What is QFE?

A

Station level pressure

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38
Q

With QFE on the subscale of altimeter, what will the mainscale indicate?

A

Height above/below the reference pressure point

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39
Q

How can you obtain the QFE for a point?

A

Set zero ft on mainscale

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40
Q

What is QFF?

A

Meterological mean sea level

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41
Q

What are isobars?

A

Lines on synoptic chart joining places of equal pressure

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42
Q

An altimeter in an aircraft flying towards a low pressure without adjusting the QNH, what will the altimeter do?

A

Over read

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43
Q

What is a col?

A

Neutral area between two highs and two lows

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44
Q

What is a trough?

A

Elongated area of low pressure

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45
Q

What is a ridge?

A

Elongated area of high pressure

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46
Q

What is pressure gradient?

A

Change in pressure with horizontal distance

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47
Q

How is pressure gradient measured?

A

High to low at right angles to the isobars

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48
Q

What does close isobar spacing indicate?

A

Strong gradient and strong winds

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49
Q

What does wide isobar spacing indicate?

A

Weak or shallow gradient and light winds

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50
Q

Pressure may be defined as:

A

Force per unit area

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51
Q

What effect does density have on aircraft performance?

A

Good performance when density is high

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52
Q

If altimeter subscale is set at 1013 what will the altimeter read?

A

Pressure height

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53
Q

While in level flight with correct area QNH set, what will the altimeter read?

A

Approx height AMSL

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54
Q

What is QFE?

A

Aeredrome level pressure

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55
Q

What is latent heat?

A

Heat which must be added to change substance to higher state

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56
Q

What is humidity?

A

Amount of water vapour contained in air sample

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57
Q

What is relative humidity?

A

Ratio of amount of water present in air sample compared to max amount that could be contained at that temp and pressure

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58
Q

What is saturated air?

A

When air sample cannot hold any extra water vapour without condensation occuring

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59
Q

When a sample of air is saturated , what is the relative humidity?

A

100%

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60
Q

What happens to humidity with increase in temperature?

A

Humidity is decreased

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61
Q

What happens to the volume, pressure and temp of a parcel of air as it rises?

A

Pressure reduces
Volume of parcel increases
Temperature decreases

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62
Q

How will air cool as it rises?

A

By expansion

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63
Q

What is adiabatic?

A

Change in temperature due to change in pressure without change in total heat energy of air sample

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64
Q

What is ALR?

A

Rate at which air sample cools as it rises

Depends on whether it is dry or saturated

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65
Q

What is DALR?

A

Air cools at 3 degrees per 1000 feet

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66
Q

What is SALR?

A

Air cools at 1.5 degrees per 1000 feet

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67
Q

What is dew point lapse rate?

A

0.6 degrees per 1000ft

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68
Q

What is a stable atmosphere?

A

Air parcel returns to original level after being forced vertically.

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69
Q

What is an unstable atmosphere?

A

Air parcel continues to rise on its own forced vertically

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70
Q

If the temperature of the air parcel being forced vertically remains greater than the environment, what is the atmosphere said to be?

A

Unstable

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71
Q

If the temperature of the air parcel being forced vertically becomes less than the environment, what is the atmosphere said to be?

A

Stable

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72
Q

What happens when ELR is less than SALR?

A

Stable conditions

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73
Q

What happens when ELR is greater than DALR?

A

Unstable conditions

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74
Q

What is a surface inversion?

A

Air close to the surface is cooled at night by conduction.

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75
Q

When is surface inversion the greatest?

A

Just before dawn when surface temp is the lowest

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76
Q

What is turbulence inversion?

A

Moderate winds at low levels cause adibatic expansion and cooling in lower layers due to mixing. If lower layer becomes cooler, inversion forms

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77
Q

What is a frontal inversion?

A

Boundary of two masses of different temperatures as warm air slides up over cooler air

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78
Q

What is a subsidence inversion?

A

Column of air subsides the top of the column undergoes greater compression and heating than the bottom. The top becomes warmer forming an inversion

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79
Q

What conditions, stable or unstable, are associated with inversions?

A

Stable

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80
Q

What are conditions like beneath the inversion?

A

Poor visibility and turbulent

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81
Q

What are conditions like above the inversion?

A

Good visibility and clear

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82
Q

What is a fohn wind?

A

Hot dry breeze blowing down the lee side of the moutain

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83
Q

With regards to the fohn wind, where is the cloud higher?

A

Higher on the windward slope due to precipitation and change in dew point

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84
Q

When a parcel of air becomes saturated and condensation occurs, what happens to latent heat?

A

Latent heat is released

85
Q

What is relative humidity?

A

Percentage degree of saturation

86
Q

How do we get dew point temperature?

A

Moist air cooled at constant pressure for it to become saturated

87
Q

What happens to latent heat when water droplets in liquid state freeze?

A

Latent heat released

88
Q

How is relative humidity measured?

A

Psychrometer

89
Q

What height is wind measured and at what average?

A

Height of 10m over open terrain as average over 10 mins

90
Q

What is a gust?

A

Sudden increase in wind lasting short time and dying suddenly

91
Q

What is a squall?

A

Sudden increase in wind by 16 knots or more lasting at least 1 min and reaching top speed of 22 knots

92
Q

What is veer?

A

Wind change clockwise?

93
Q

What is back?

A

Wind change anticlockwise

94
Q

How does wind flow in pressure areas?

A

From high to low pressure, across isobars

95
Q

Where is the strength of the gradient force measured?

A

Perpendicular to isobars

96
Q

Due to the earths rotation, which direction is the air deflected and what is this known as?

A

To the left in the southern hemisphere

Coriolis effect

97
Q

The stronger the winds, what happens to the coriolis effect?

A

It is also stronger

98
Q

Which direction does wind flow in low pressure?

A

Clockwise

99
Q

Which direction does wind flow in high pressure?

A

Anti clockwise

100
Q

What is the pressure like in the equatorial trough?

A

Long belt of low pressure

101
Q

As air cools in the ITCZ, what happens?

A

Descends in sub tropical regions and creates sub tropical ridge of high pressure

102
Q

What is the pressure like at the poles and why?

A

Cold and dense air creates polar high pressure

103
Q

What is the sub polar low?

A

Air moving out of polar high at surface converges with air flowing out of sub tropical ridge and is forced up forming low pressure belt

104
Q

During summer in the souther hemisphere, what happens to equatorial trough?

A

Moves south to lie across norther Australia

105
Q

What does equatorial trough moving south in summer in southern hemisphere do to weather?

A

Draws warm, moist air and therefore rain (northwest monsoon)

106
Q

What is the difference between the movement of the equatorial trough in the southern and norther hemisphere in summer?

A

Moves further north from the equator in summer due to greater area of land in northern hemisphere

107
Q

What are the winds over norther australia like in winter?

A

South eastly due to south east trades

108
Q

What does winter weather like in northern australia? What about east coast

A

Dry except over east coast where trade winds contain abundant moisture

109
Q

What is the South east trade wind?

A

Wind from the sub tropical ridge towards the equatorial trough

110
Q

What is the roaring 40s?

A

40 degrees south.
Air flows from sub tropical ridge towards sub polar low.
In Southern hemisphere, north westerly

111
Q

When coriolis matches gradient force, which direction does gradient wind flow?

A

Gradient wind flows parallel to curved isobars

112
Q

What is the friction layer?

A

Lower 3000 ft of atmosphere

113
Q

What happens to wind in friction layer over land and sea?

A

Over land speed reduced by 2/3

Over sea speed reduced by 1/3

114
Q

What happens to wind and coriolis force in friction layer?

A

Reduced coriolis force

Wind reduces and veers

115
Q

What happens to wind above friction layer?

A

Wind flows parallel to isobars

116
Q

Surface wind around a low pressure in southern hemisphere blows what direction?

A

Clockwise and inward

117
Q

What are the high level clouds and what are the cloud bases above?

A

Cirrus
Cirrostratus
Cirrocumulus
Bases above 20000ft

118
Q

What are cirrus clouds like?

A

White Fibrous or Threadlike Appearance.
Little turbulence unless associated with a jet stream.
Nil Icing.

119
Q

What are cirrostratus clouds like?

A

White, Sheet or Layer. Halo Phenomena.
Turbulence may be felt on entering cloud, usually only light.
Usually too high for significant icing

120
Q

What are cirrocumulus clouds like?

A

Global form of cloud indicates presence of turbulence.

Too high for significant icing. Cloud usually dissipates rapidly.

121
Q

What are thin altostratus clouds like?

A

Medium level.
Bluish sheet or layer.
Virga may be encountered.
Little turbulence in cloud. Distinct bumps felt on entering or leaving cloud.
Some icing risk. Usually light rime ice, as cloud particles are small and temperature is
usually low

122
Q

What are thick altostratus clouds like?

A

Bluish sheet or layer. Sun appears as through glass at thinner portions.
Light to moderate rain or snow.
Generally light turbulence in cloud; may be moderate to severe at fronts, over highlands.
Bumps on entering or leaving.
Definite icing risk. Moderate rime. Clear ice possible in lower levels of clouds.

123
Q

What are altocumulus clouds like?

A

Middle level cloud. White to grey.
Usually light turbulence.
Nil Icing

124
Q

What are altocumulus lenticularis clouds like?

A

Lens or almond shaped.
Form of cloud indicates waves, which form in the atmosphere with consequent
turbulence, usually not severe.
May be light rime ice

125
Q

What are altocumulus castellanus clouds like?

A

Turret or castle shaped protuberances on common base.
Possible rain showers.
Moderate to severe Turbulence.
May be light rime ice.

126
Q

What are cumulus clouds like?

A

Low level, Cellular, Flat base, Small vertical extent, Cauliflower shaped.
Light to Moderate turbulence.
Little icing risk. Freezing level usually above cloud.

127
Q

What are large cumulus clouds like?

A

Low level, Cellular, Flat base, Large vertical extent, Cauliflower like.
Showers of rain
Moderate/severe turbulence in and below cloud. Violent on entering or leaving.
Definite icing risk. Clear ice just above freezing height.

128
Q

What are cumulonimbus clouds like?

A

Cellular, Very large vertical extent. Tops fibrous or striated, may be in shape of anvil.
Thunderstorms, lightening, showers of rain, snow or hail.
Severe turbulence both in and below cloud. Very violent on entering or leaving.
Definite icing risk. Dangerous clear ice possible.

129
Q

What are stratocumulus clouds like?

A

Mostly grey.
May be drizzle
Light to moderate turbulence beneath and in cloud, bumpiness passing through inversion
at cloud top, smooth above.
Occasional Rime ice if freezing level is low enough

130
Q

What are stratus clouds like?

A

Greyish, generally thin sheet or layer. May be ragged.
May be drizzle
Light turbulence. May be inversion as with Sc (Cloud limited due inversion)
Usually nil icing.

131
Q

What is fog?

A

Cloud on the ground
Visibility below 1000 metres. Obliterates view of ground.
Nil turbulence.
Nil Icing

132
Q

What is orographic uplift? And what happens in stable and unstable conditions with it?

A

Air forced up mountain
Air cools adiabatically
If stable, stratiform or nimbostratus clouds form, if unstable cumliform cloud

133
Q

What are mountain waves?

A 
Orographic uplift at right angles to the range with speed increasing to at least 25kts at top of range AND
Stable layer (inversion) above range
134
Q

What is a passage of a cold front marked by?

A

Barbs pointing direction cold front is moving

135
Q

What temp, wind and pressure happens in cold front?

A

Fall of temp
Back of wind
Rise in pressure

136
Q

What temp, wind and pressure happens in warm front?

A

Rise in temp
Back of wind
Fall in pressure

137
Q

A cold front usually lies along?

A

Trough of low pressure

138
Q

A cold air mass is characterised by?

A

Unstable conditions and cumuloform clouds

139
Q

Defined boundary between two air masses is called?

A

Front

140
Q

Warm air masses are characterised by?

A

Stable but hazy conditions

141
Q

What happens to warm and cold air at cold front?

A

Cold air is dissipating warm air at the surface

142
Q

What happens to warm and cold air at warm front?

A

Warm air slides over cold air at surface

143
Q

What weather scenario follows passage of warm front?

A

Nil significant weather

144
Q

Where do cyclones form?

A

Between 5 and 15 degrees north or south of equator

145
Q

Where does cyclone get its energy?

A

Heat stored in tropical waters. And from latent heat released during condensation and cloud formation

146
Q

What is the life cycle of a cyclone?

A

Formative
Immature
Mature
Decaying

147
Q

What happens in formative stage of cyclone?

A

Existing depression deepens
Winds reach gale force (greater than 34 knots)
Eye develops

148
Q

What happens in the immature stage of cyclone?

A

Pressure falls below 1000HPa
Winds reach hurricane force (greater than 64 knots)
Spiral bands form
Storm radius 30-50km

149
Q

What happens in the mature stage of cyclone?

A

Pressure steady
Area of storm expands
Hurricane force winds can expand up to 300 km away

150
Q

In the southern hemisphere, where is the most destructive part of cyclone?

A

Front left quadrant

151
Q

What happens in the decaying stage of cyclone?

A

Pressure begins to rise
Storm contracts
If land is encountered, cyclone turns into rain depression

152
Q

When is cyclone season in Australia?

A

November to April

153
Q

How does fog form?

A

Air cooled below dew point temperature

154
Q

What is fog?

A

Cloud at ground with visibility less than 1000m with relative humidity near 100%

155
Q

What is mist?

A

Visibility greater than 1000m

Relative humidity less than 100%

156
Q

How is fog formed by radiation? What conditions?

A

Air close to ground cooled

Clear night with moist air, inversion and light wind (6kts)

157
Q

When is radiation fog most intense?

A

Dawn when surface temperatures are the lowest

158
Q

How is fog formed by advection? What conditions?

A

Warm moist air cools as it flows over cool surface

159
Q

When does fog disipate?

A

Air temperature raises above dew point

Wind mixes dry air

160
Q

What conditions must exist for thunderstorm?

A 
Unstable conditions (steep ELR)
Abundant supply of water (high humidity)
Lifting mechanism to trigger (heat, front terrain, convergence)
161
Q

What happens in the cumulus (developing) stage of a thunderstorm?

A

Updraughts as cloud builds.

Cloud is warmer than the environment so vertical development continues

162
Q

What happens in the mature stage of a thunderstorm?

A

Cumulonimbus Cloud with anvil shaped top
Rain falls
Strong down and up draughts
Drop in temp ahead of storm

163
Q

What happens in the dissipating stage of a thunderstorm?

A

Only down draughts
Rain decreases
Cloud breaks up

164
Q

How long does a storm last?

A

Approx 60 mins

165
Q

What is a frontal thunderstorm?

A

Formed by instability at boundary between two air masses.

Closely spaced and fast moving

166
Q

What is cold stream thunderstorm?

A

Cold air over warm surface

167
Q

What are the hazards of thunderstorm?

A

Severe turbulence
Heavy rain, hail
Lightning

168
Q

What are jet streams?

A

Fast moving narrow current of air

169
Q

Where are jet streams found?

A

Near the tropopause

170
Q

What characterised jet stream?

A

Strong horizontal wind shear

171
Q

Surface wind compared to gradient wind does what with regard to backing/veering and speed?

A

Surface wind veers to the right and is slower

172
Q

Over land, what does surface wind do?

A

Veers by 30 degrees and slowed by 2/3

173
Q

Anticyclonic wind flows about what?

A

High in southern hemisphere

174
Q

What does a Fohn wind do to humidity at mountains?

A

Lower humidity on lee side of mountain at low level

175
Q

What does surface friction do to coriolis effect?

A

Decreases it

176
Q

When is conditional stability said to occur?

A

SALR is unstable

DALR is stable

177
Q

What cloud produces virga?

A

Thin altostratus

178
Q

What is a low level jet?

A

Fast moving stream at low level

179
Q

How is a low level jet formed?

A

Air circulating around a high hit mountain range and accelerated into narrow stream along the range

180
Q

What must be present for a low level jet?

A

Surface inversion

181
Q

When are max speeds of low level jet ?

A

Early morning

182
Q

What conditions will result in considerable lee side turbulence?

A

Stable conditions

183
Q

What is a sign of turbulence near mountains?

A

Lenticular clouds with rotor cloud under

184
Q

What is the common temp for rime ice to form?

A

-10 to -20

185
Q

What cloud types can you get rime ice in?

A

Stratiform clouds

186
Q

How does rime ice form?

A

Small super cooled droplets freezing on impact with aircraft surface

187
Q

What is the common temp for clear ice?

A

0 to -15

188
Q

When can clear ice be encountered?

A

Cumuliform clouds above freezing level

189
Q

What icing is there in altostratus?

A

Light rime

Clear ice if very thick

190
Q

Meteorological visibility refers to what?

A

The greatest visibility prevailing over half or more of the horizon

191
Q

What does INTER on forecast mean?

A

Phenomena expected to last for less than 30 mins

192
Q

What does TEMPO mean on the forecast?

A

Phenomena expected to last for less than 60 mins but more than 30mins

193
Q

If conditions are colder than ISA what does the altimeter do?

A

Sense lower pressure and OVERREAD

pilot believe they are higher then they are

194
Q

If conditions are warmer than ISA what does the altimeter do?

A

Sense higher pressure and UNDERREAD

195
Q

What is the rule of thumb for operating at higher altitudes and ISA temp/pressure deviation

A

4% of indicated height per 10 degrees of variation from ISA

196
Q

Where are jet streams often found?

A

Breaks in the tropopause

197
Q

What are jet streams like?

A

Strong horizontal and vertical wind shears and speed in excess of 60knots

198
Q

What direction are jet streams?

A

Westerly

199
Q

Where is CAT considered most severe?

A

On the polar side of the jet stream below the level of the core.
Also in winter

200
Q

What is an isotach?

A

Join points of equal wind speed showing the max wind speed in the jet core

201
Q

Where are strong down draughts close to the ground, air mass or frontal thunderstorms?

A

Strong down draughts close to the ground are more likely beneath frontal

202
Q

What conditions are more favourable for formation of low level jet across souther QLD?

A

Early morning
Clear sky
HIGH centred to the west of GDR

203
Q

What conditions are required for dust storm of Adelaide?

A

Approaching cold front

High pressure area to the East

204
Q

What would there be with a fast moving cold front?

A

Broken cumliform clouds

Rain showers

205
Q

What conditions are required for a dust storm?

A

Land surface dry and dusty
Wind at least moderate
Unstable atmosphere

206
Q

What is the most likely cause of turbulence over land on a hot day?

A

Thermal convection

207
Q

What type of cloud is associated with unstable air over a mountain?

A

Cloud with extensive vertical development

208
Q

What happens to the wind, temp and pressure with the passage of a cold front?

A

Wind backs
Temp falls
Pressure rises

ATPL Met (1 decks)

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