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Meteorology Flashcards

1
Q

The out-flowing in a mature thunderstorm

A

Usually is greater in the direction of the thunderstorm

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2
Q

Why is the temperature colder in polar region

A

The solar radiation is lesser per unit area as compared to the tropics

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3
Q

What is a visual sign of a mature thunderstorm

A

Cumulus growing over layered clouds like stratocumulus or altocumulus

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4
Q

There is a sea Breeze in the late morning of a summer. Which of these will explain what happens to the surface conditions above the land when the wind moves across?

A

Temperature will drop, dew point will increase

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5
Q

How is an airmass created?

A

When air remains stagnant over land or sea and develops similar properties

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6
Q

Which is true of polar front jet streams

A

They are located in the warm sector and are ahead of the frontal area at latitudes of 40-50deg

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7
Q

Questions asks about how is hail generated

A

Option chosen was the one that says strong updraughts in CB, with most of the cloud above freezing level and with supercooled water droplets.

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8
Q

How is SWD formed

A

… due to lack of freezing nuclei, the water remains in unstable state below 0degC as SWD

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9
Q

Image shown of flight from HK to SG. They ask what is the average wind speed at 5N

A

070/40, -53degC

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10
Q

Which of the following will most likely lead to the formation of Low level stratus clouds

A

Moist air moving over a relatively cooler sea, with wind speeds in excess of 15kts

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11
Q

How do you distinguish cumulus clouds

A

Segregated segment of clouds….

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12
Q

Rime ice

A

Instantaneous icing with small SWD

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13
Q

Which of this is the correct code used in METAR?

A

GR: Hail or big snow, precipitate with diameter more than 5mm

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14
Q

Wind shear at a friction layer is most pronounced when

A

Density of friction layer is maximum just before dawn

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15
Q

What is conduction

A

“… in direct contact with each other and at different temperatures so there is some heat transfer…”

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16
Q

After passage of warm front, 1 hour later you are in the warm sector. What would you expect to see in the warm sector?

A

More or less constant QNH, light and intermittent rain, Low and extensive clouds, Low vis

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17
Q

In the SH, where do trade winds originate from

A

From sub tropical high belt, and move from SE

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18
Q

What’s the expected weather like in South Asia under the SW monsoon?

A

Option with most severe conditions.

Heavy turbulence, thunderstorms, etc

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19
Q

What’s the length of jet stream

A

2000nm

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20
Q

Definition of subsidence inversion

A

When air sinks, it heats up adiabatically…

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21
Q

Anti-cyclonic at the surface, cold surface, how to pressure levels appear

A

Bulges down, and decrease in strength as altitude increases

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22
Q

Bergeron theory of rain formation

A

Some supercooled water droplets will turn to ice and grow by sublimation and fall as snow or rain, depending on temperature

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23
Q

Weather conditions for blocking high systems

A

Good weather for Long time

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24
Q

What type of wind shear may be reported in a METAR

A

All reported wind shear

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25
Q

What is a mistral

A

A valley wind

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26
Q

RVR measured in

A

Metres

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27
Q

Tornadoes are formed by

A

Strong up currents within CB

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28
Q

Which of the following best describes the formation of tornadoes

A

Strong updraft within CB

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29
Q

There is Low pressure near the surface and there is some pressure aloft. Does it bulge up or down

A

Bulge down rises and reduces in size

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30
Q

When is diurnal variation the greatest?

A

Mid-afternoon

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31
Q

Diurnal variation of relative humidity

A

RH decreases by day, increases by night

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32
Q

FL180 which charts do you use

A

500hPa

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33
Q

What is true altitude?

A

Actual altitude above AMSL

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34
Q

Given FL330, calculate true altitude if ISA deviation is +7degC

A

33924ft (closest is 34000ft)

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35
Q

Which is the severe most quadrant for the Cyclones in the SH?

A

Left front quadrant

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36
Q

Pressure gradients are measured for practicality purposes

A

From high to Low pressure

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37
Q

Pressure gradient is measured

A

Perpendicular to isobars

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38
Q

What is the weather at a Col

A

Not much weather

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39
Q

What is the weather around a Col in winter

A

Low vis and fog

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40
Q

What weather can you expect in Col winter

A

Light winds, fog…

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41
Q

What is set on AC altimeter if it shows 0ft on the ground

A

QFE

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42
Q

What affects the type of icing

A

Type of droplets, water vapour content and air temperature

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43
Q

What are the conditions to clear ice formation

A

When droplets are large

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44
Q

When an air mass goes to a warmer area what happens

A

Becomes unstable, convection occurs, Cu Cb form in day with good vis

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45
Q

Why is SALR lower than DALR

A

Due to heating caused by condensation and release of latent heat

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46
Q

Why are poles colder than equator

A

Due to sun more directly overhead equator than poles

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47
Q

Solar radiation is reflected back to space due to

A

Clouds

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48
Q

What are the weather phenomena indicating an area of jetstreams

A

Cirrus streaks, change in wind speeds and CAT

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49
Q

What are the met signs that you are approaching a jet stream while flying

A

Change in temperature, winds and drifts, CAT

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50
Q

Which area of jet stream would you experience the worst CAT

A

Core to the Low pressure side

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51
Q

Severe turbulence is

A

Large and abrupt movement of AC in the 3 axes, pilot losing control of AC definitely, but briefly, and loose articles gets tossed

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52
Q

What is an AIRMET

A

MET info along air route

Info for met conditions

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53
Q

Geostrophic wind is the balance of what

A

Coriolis and pressure gradient force

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54
Q

What is an orographic depression

A

Flow of air meets mountain range at large angle , causing air to flow around, instead of over the TOP

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55
Q

During months of June to September, where is the wind coming from Singapore

A

S and SW monsoon

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56
Q

What are tradewinds characteristics

A

Steady, 10kts

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57
Q

An air mass at its origin is

A

Stable

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58
Q

What happens to the winds and pressure when a warm front passes you

A

It veers

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59
Q

Size of drizzle

A

0.2mm to 0.5mm

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60
Q

In what units is wind reported in TAF and METAR

A

True/kts

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61
Q

What is the weather in a quasi-stationary front

A

Little/no weather

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62
Q

Where will the TU be at 100Z

A
  1. 440 to 118.00

224. 40 to 11.800

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63
Q

During the summer of SH where do you expect the ITCZ to be in the South Pacific

A

Mainly below equator but slightly above in central South Pacific

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64
Q

Why is the main cause for general circulation

A

Transfer of heat from equator to polar region

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65
Q

What is the average altitude and temp of tropopause for tropical regions

A

55000’ to 60000’ , -70degC

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66
Q

The tropopause over the equator is at FL_____, while it is at FL_____at the poles. Compared to the poles, the tropopause at the equator is

A

520, 280, colder

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67
Q

The tropopause height is higher

A

Over the equator and the temperature is colder

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68
Q 
260/55
250/75
Variation 9degE
TAS 457kts
Find the true heading
A

220deg / 410kt

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69
Q

Where does the Harmattan blow to

A

Hot, dusty winds blowing across Sahara desert

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70
Q

Where does the cirrus cloud form at a jet stream

A

Below towards warm side

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71
Q

What weather is expected when tropical maritime air blow towards U.K. or Europe during winter

A

Fog/Stratiform

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72
Q

What weather can you expect when passing through a cold front in NH

A

Steady or slight veer to NW, Cu Cb

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73
Q

You left your aircraft for 3 hours coming back after to find your altimeter reading has increased. What is the likely reason?

A

QNH decreased

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74
Q

Where is a RVR reading taken from

A

Specific location and down one direction

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75
Q

The met measurement of RVR is described as

A

Distance measured by an electronic device where intensity of light a known distance away is measured by a photoelectric cell

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76
Q

Which would be a correct instrumented RVR reading

A

R20R/300U

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77
Q

RVR 400 450 500. Where are they measured?

A

Touchdown, midpoint, end-point

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78
Q

Cyclone formation in the South Pacific between the meridian

A

140E 160W

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79
Q

Tropical cyclones in the SW Pacific usually occurs

A

Between 5degS and 20degS

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80
Q

Where are the tropical storms found in the Pacific in the Southern Hemisphere

A

5-25 degrees South, 140W to 160E

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81
Q

A thermal wind is

A

Affected by Buys Ballot Law and blows to the right when moving from an area of Low pressure to High pressure in the SH

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82
Q

The ozone layer

A

Absorbs UV radiation and warms the atmosphere

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83
Q

Which of the following corresponds to Koppen’s climate classification

A 
A: Tropical 
B: Arid/Dry
C: Temperature (warm)
D: Continental (snow)
E: Polar
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84
Q

Where will wake turbulence be encountered

A

Below and just behind the flight path of a clean, heavy aircraft flying at Low speed

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85
Q

What is the ISA condition at sea level

A

15degC, 1013hPa

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86
Q

A high level chart with height specific isobaric levels is known as

A

A constant pressure chart

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87
Q

What is the rate of accretion of icing over mountains like?

A

Heavy because atmosphere is disturbed due orohraphic effect

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88
Q

Why icing risk is higher in orographic lifting

A

Air being forced up contains more supercooled water droplets

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89
Q

When will you expect a wet monsoon to occur over Singapore?

A

Oct - Mar (or Jan-Mar)

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90
Q

What happens when a given parcel of air is cooled?

A

Relative humidity increases, dew point & absolute humidity remains the same

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91
Q

What are the required conditions for the formation of TRS

A

Water 27degC, <1000hPa, convection

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92
Q

Surface chart with a high to the left of Ireland and Low over north west France. Determine direction of surface wind

A

030T

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93
Q

In summer over British isles, what sort of weather will you expect with a tropical continental air mass

A

Warm or very warm weather with dusty conditions

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94
Q

A jet stream is formed from a

A

Horizontal temperature difference

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95
Q

What causes nocturnal thunderstorms in the tropics

A

The sea is being warmed and air cooling at night

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96
Q

What triggers precipitation in the air masses

A

Orographic lifting and convective currents

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97
Q

With respect to jetstreams, what are the relative height of a tropopause

A

The tropopause is higher on the tropical side than the polar side

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98
Q

For which altitude would you use a 500hPa chart

A

FL180

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99
Q

Refer to figure above, what is the flight level you can expect CAT along the flight path from Sydney, in red?

A

FL250 - 530

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100
Q

Refer to figure above, what is the approx speed of the jet stream you can expect when flying at FL390 along the flight path from Sydney, in red?

A

160kts

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101
Q

Refer to figure above, what is the tropopause height along the flight path from Sydney, in red, towards Hong Kong?

A

FL420 - 500

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102
Q

With high level of divergence, air at the surface would,

A

Converge and ascend

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103
Q

With high level divergence, air at the surface would

A

Diverge and descend

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104
Q

Refer to the figure above, what is shown

A curve with semi circles on TOP

A

Warm front

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105
Q

Which of the following represents a squall line

A

—— .. ——- .. ——-

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106
Q

In a blocking high in the South Pacific, the vertical profile would be

A

Weak divergence at lower levels and strong convergence at high levels

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107
Q

What happens in a blocking anticyclone

A

Subsidence, intense in upper troposphere, weak in lower troposphere

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108
Q

Where can info about volcanic ashes in the atmosphere be found

A

In SIGMET and in ACCA notices

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109
Q

Volcanic ash advisory is reported to who / goes to who

A

Pilots

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110
Q

What does the above symbol represents on a weather chart

Looks like a bell, with 3converging sticks on TOP

A

Volcanic eruption

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111
Q

Which conditions best promotes the development of radiation fog

A

Night time or dawn with clear skies, light wind and high relative humidity

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112
Q

What does advection fog form

A

Over cold land or sea with warm moist air

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113
Q

When temp is said tone ISA +2degC, it means

A

At the pressure altitude, temp is 2degC warmer than ISA temp typical of the altitude

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114
Q

Diff between FL and altitude

A

FL is constant pressure level and altitude is constant distance from MSL

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115
Q

On which surface will ice accretion occur first

A

Leading edge of tailplanes and aerials

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116
Q

First aircraft icing most likely to be

A

On wings upper and lower surface

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117
Q

How does surface and speed affect the rate of ice accretion

A

Sharp surfaces at high speed increase accretion rate

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118
Q

Which of the following is correct

About two letter code

A

GR: Hail, iceballs of diameter greater than 5mm

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119
Q

Which of the following does not favour the formation of standing mountain Lee waves

A

Winds varying direction as altitude changes

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120
Q

What factors are required for standing waves

A

Low level 15kts and increasing with altitude and a stable layer above the ridge blowing nearly or perpendicular to the ridge

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121
Q

The following is a forecast at an aerodrome

Tons of numberssss

Local magnetic variation is 20degW. If you are flying inbound on a holding pattern at 5000’ at 100degM, what will be the headwind component

A

-10

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122
Q

Geostrophic wind is caused by

A

PGE, coriolis force

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123
Q

Coalescence theory is

A

Assumption presence of the range of droplets sizes larger falling faster to meet smaller droplets and fall as rain

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124
Q

Bergeron theory is unable to explain the formation of precipitation uncertain cases because

A

Not all water droplets are supercooled

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125
Q

In an occluded front

A

Cold air behind the cold front undercuts the warm air and cold air ahead of the warm front , and it is called a cold occlusion

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126
Q

What is the weather at a cold occlusion

A

Embedded Cb. Most of the precipitation is behind the surface position of the occlusion

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127
Q

Low level wind shear associated with the Top of the friction layer will be at its

A

Maximum when layer density is greater before dawn

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128
Q

Main diff between microburst and downburst, is that microburst

A

Can only occur singly

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129
Q

Virga is

A

Rain that sublimates before reaching ground, absorbing latent heat and cooling surrounding air

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130
Q

In convective clouds

A

Saturated air is cooled, water vapour condenses, releasing latent heat, heating the cloud relative to surrounding air and intensifying the convective effect

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131
Q

Water vapour in air

A

Cannot be seen as it is a gas

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132
Q

At 40degN latitude, the prevailing wind is

A

Westerly

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133
Q

At 3000ft just above a Low level inversion, what kind of cloud do you expect

A

CB

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134
Q

Flying at 3000ft in cloud, you experience light turbulence and light icing, from which cloud is this the most common

A

SC

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135
Q

How is radiation fog lifted

A

Insolation

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136
Q

What are the conditions that favours radiation fog to dissipate

A

Insolation and strong wind blowing the surface

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137
Q

What causes year round thunderstorms in the tropics

A

ITCZ

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138
Q

The tropopause can be defined as

A

Where the decrease in temp with altitude ceases

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139
Q

When a particle is struck and part of the solar radiation is reflected back to space and part of it warms the atmosphere, this is known as

A

Reflection

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140
Q

How does the wind direction and strength change from surface to upper levels in the Southern Hemisphere

A

It is constant in the friction layer but suddenly increases speed and backs above the friction layer

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141
Q

At 18Z, where is TS PACHU expected to be at?

A

22.32N 116.00E

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142
Q

Low temp will

A

Increase density and pressure lapse rate

143
Q

What happens when increase in temp to density and pressure lapse rate

A

Both decrease

144
Q

What measures the cloud base

A

Ceilometer

145
Q

Occlusion in a synoptic chart will show triangles

A

And half circles both drawn on the side towards the advancement of the front

146
Q

What info would you expect to see in a VOLMET

A

Visibility

Wind shear

147
Q

What are the requirements for lenticular clouds to form

A

Stable moist air flowing over mountain with dryer air

148
Q

What causes lenticular clouds

A

Mountain waves in the Lee of the mountain range

149
Q

Why is CAT normally found in the vicinity of jetstreams

A

Because of the horizontal and vertical wind shear

150
Q

Why is there an inversion in the higher atmosphere

A

The reaction of the ultraviolet radiation and the ozone layer

151
Q

Why temp is constant with the increase in altitude at stratosphere

A

Due to absorption of UV light by ozone molecules

152
Q

QNH is

A

Set when aircraft below transition altitude

153
Q

What is area R

A

Col/Flat pressure area

154
Q

What do you call an area of pressure with 2 anticyclonic pressures and 2 Low pressures

A

Col

155
Q

A trough is a system of

A

Low pressure and the pressure is lower in trough than on both sides

156
Q

A trough is an _____ of an area of Low pressure with characteristics

A

Extension

Similar to its parent Low

157
Q

A ridge is an area of

A

High pressure with the pressure on both sides of the extended centre lines of the ridge lower than in the ridge

158
Q

The action of solar radiation being returned to upper atmosphere is

A

Reflection

159
Q

What is a sign of mid level stability

A

Altocumulus castellanus

160
Q

What happens during cumulus cloud formation

A

Condensation causes latent heat to be released, warming the surrounding air and causing an increase in rising effect

161
Q

What is displayed when the altimeter is set to 1013mb

A

Pressure altitude

162
Q

A gust is

A

Rapid increase in wind strength lasting less than 1 minute

163
Q

What causes rime icing

A

Small supercooled water droplets

164
Q

What order of clouds would you expect to see ahead of a warm front

A

Ci, Cs, As, Ns

165
Q

What type of cloud is layered and dark, producing extensive precipitation

A

Ns

166
Q

What cloud brings about heavy showers

A

Cu, Cb

167
Q

Subsidence inversion is

A

As the air descends, it will be heated adiabatically and will be warmer than the air at a lower level

168
Q

When there is more water vapour in the air, the dew point

A

Increases

169
Q

The Fohn wind is

A

Warm dry air blowing on the Lee side of a mountain

170
Q

Upcurrents in a thunderstorm

A

Predominates the growing stage

171
Q

Oktas are measured in terms of

A

Eights

172
Q

When temp falls, becoming colder

A

Density increases, pressure lapse rate increases

173
Q

Intermittent rain will be most common to which type of cloud

A

St, Sc

174
Q

What type of icing may occur during a rapid descent

A

Hoar frost

175
Q

With a wind speed of 34kts and The Eye developed - What stage of TRS

A

Mature

176
Q

Lines on a chart showing areas of equal temperature are known as

A

Isotherms

177
Q

In the mature stage of a thunderstorm

A

Both up and downdraughts with downdraughts restricted to the front part of thunderstorm

178
Q

A cold front is depicted on a contour chart

A

By a boundary on the surface between air masses

179
Q

What weather can be expected when polar maritime air flows over a colder region

A

Light precipitation

180
Q

Why is there no icing hazard when OAT is below -30degC

A

At those temp, there is less supercooled water droplets and most of the precipitate is dry ice crystals

181
Q

Tropical cyclone advisory service is

A

To monitor tropical cyclones and advise to met offices

182
Q

METAR wind is given in

A

True

183
Q

TAF VHHH 211700Z 2118/2300 ______ how Long is this TAF valid?

A

30 hours

184
Q

The temp is constant and you fly to a Low pressure area. What happens to the indicated altitude

A

Over reads

185
Q

Fly from area of high pressure to Low pressure, what will your altimeter indicate

A

It will over read

186
Q

What happens to the surface wind over the sea in the Northern Hemisphere

A

Speed decreases by 30%, and backs by 10deg

187
Q

CF and PGF act

A

Opposite to each other

188
Q

In a lenticular cloud, ice is formed

A

At a slow rate as lenticular clouds generally have fair weather

189
Q

Clear ice at temp of 0degC to -15degC are common due to

A

More large SWD

190
Q

Which is reported in PIREP/AIREP

A

Moderate icing

191
Q

Which observed conditions would require special aircraft observation to be made

A

Volcanic activity

192
Q

In the SH, where do the trade winds blow

A

From sub tropical high SE

193
Q

Flying over Singapore in July

A

Winds are easterly

194
Q

Once it first hits the ground, a downburst will typically last about

A

5-30 minutes

195
Q

Orographic Low

A

Occurs on the Lee side of the mountain, bad vis, cloudy skies

Leeward side, bad weather all blown to the other side

196
Q

Orographic thunderstorms

A

Usually stays over area of development

197
Q

Terrestrial radiation heat transfer

A

Due to earth absorbing and emitting sun’s radiant energy and sending it back to space

198
Q

Atmospheric inversion is

A

Temp increases with height

199
Q

Ozone at high levels

A

Absorbs sun radiation and warms atmosphere

200
Q

Thermal thunderstorms in the day in the tropics are due to

A

Convergence of ITCZ

201
Q

Thermal heating in the tropics causing rain due to

A

Convergence of ITCZ

202
Q

Mechanical Turbulence

A

Increasing with decreasing ELR

203
Q

Length of warm sector

A

150nm

204
Q

The transition between cold air and warm air in the warm sector is

A

25 - 120km

205
Q

Weather behind active cold front

A

Cu, poor vis and turbulent

Cu and Cb cloud, heavy showers, poor vis

206
Q

In front of a cold front

A

Calm with excessive ST

207
Q

Frontal thunderstorms greatest activity

A

Cold front is rapid and very cold

208
Q

In general, the intensity and activity of frontal thunderstorms are greatest with

A

Cold fronts which moves at a rapid rate

209
Q

Effect of smoke particles on condensation

A

Occurs more readily

210
Q

Fohn wind strong moist air blowing at almost right angles to mountain range

A

Light winds at Low altitude; strong winds higher up

211
Q

Characteristics of Fohn wind

A

Dry and warm katabatic wind flowing down LEE side of the mountain

212
Q

Thermal thunderstorms occur

A

Mid early to mid afternoon, sometimes lasting into evening

213
Q

State reason why water vapour is less dense than air at constant temp

A

Air is heavier than water

214
Q

Dry air and moist air at constant pressure and temp. Which is denser

A

Moist air is less dense than dry air

215
Q

Compare dry air with saturated air

A

Dry air heavier than saturated air

216
Q

Is air with more water vapour less dense

A

True. Water molecules have less mass than air molecules

217
Q

TRS occurring in SW occurs _____ times from the months ____ -_____

A

8

12-4

218
Q

As air temp increases during the day of ‘settled weather’, the base of the convective cloud

A

Rises

219
Q

What cloud type does convection give rise to

A

Cumulus

220
Q

During cycle of thunderstorm, the stage during which freezing air bulges down relative to level outside is

A

Mature stage

221
Q

What conditions is most ideal for high altitudes contrails to prevail in atmosphere

A

Air that is saturated with water vapour, which speeds up sublimation

222
Q

Where are the light easterly waves found

A

10N - 20N

223
Q

What absorbs the sun radiation before before hitting the earth surface. Why is there a temp inversion in the stratosphere

A

Ozone absorbs ultraviolet, water vapour absorbs infrared

224
Q

Process where increase in temp due to addition of heat energy from external heat source

A

Non-adiabatic

225
Q

At what pressure can you find the artic or polar jet stream

A

300hPa

226
Q

Polar jetstream in terms of polar front

A

On top of surface front

227
Q

At which stage of thunderstorm will there be downdraughts

A

Mature

228
Q

Who is the function of world area forecast system for

A

For all aeronautical users

229
Q

What is the weather over Azores High

A

Tropical maritime

230
Q

Given observed temp over Singapore is -54degC. Given a map of FL390. What is the ISA deviation

A

+3degC

231
Q

Study the isobar patterns above. What is true for the image above in the Southern Hemisphere

A

If wind is easterly at C-D, the region C-D depicts a trough and A-B depicts a Ridge

232
Q

What forms drizzle

A

Stratus clouds with Low winds

Weak updraughts into shallow layered cloud

233
Q

Blocking anticyclone blocks _____ movement of system and it occur when zonal index is_____

A

Eastward, High

234
Q

Land Breeze

A

In a summer night, land is cooled a little bit

235
Q

Land Breeze. When and how it happens

A

Happens at night. When land cools and pressure is higher on land, resulting in air to blow from land to sea

236
Q

Which statement is true for CF and PGF

A

PGF goes high to Low while CF is always right angles to wind direction

237
Q

What does pulse radar Doppler detects

A

Particle speed

238
Q

Which type of clouds gives the most icing

A

Cumulonimbus

239
Q

Airplane below cloud of supercooled water droplets but above freezing level, when it levels off will there be icing? (Some diagram shown)
Freezing level is below cloud, the aircraft will cruise between cloud base and the freezing level

A

Yes there will be significant icing in freezing rain

240
Q

Volcanic ash is advised by

A

VAAC

241
Q

Winds above friction layer in Southern Hemisphere

A

Not much variation until out of friction layer, then increase and back

242
Q

Which air mass would result in dry and cold air

A

Continental polar

243
Q

What altitude for tropopause in tropical region

A

16km, 48000ft (should be around 55000ft)

244
Q

What precipitation does stratocumulus has

A

Light rain/drizzle

245
Q

Gradient wind vs Geosptrophic wind around area of Low pressure

A

Geostrophic wind more than gradient wind

246
Q

Sea Breeze: North facing coast with a slack pressure gradient over the area. Where do you expect the wind to be from, on a hot sunny day

A

360deg / 15kts

247
Q

What is the effect of carbon monoxide in the atmosphere

A

Absorb Long wave radiation

248
Q

How should a pilot adjust pressure setting

A

Use elevation of airfield if QNH not given

249
Q

In which conditions is the turbulent layer thickest

What causes mechanical turbulence

A

Strong winds, large buildings, rough surface, unstable air

250
Q

A warm front is

A

Warm air displacing cold air

251
Q

What weather would your expect with an approaching warm front

A

Precipitation increasing in intensity, then after the front passes, intermittent showers

252
Q

Passage of warm front

A

Wind veers.. pressure falls… dew point and temp increases

253
Q

A warm front just passed you, 1 hour later?

A

Steady QNH, various with Low clouds, intermittent drizzle

254
Q

What weather behind a warm front

A

More or less constant QNH

255
Q

What sort of clouds observed behind a warm front

A

Altocumulus, cumulus, clear skies

256
Q

What is conduction

A

Air molecules that have different temperature interact, and sensible heat is transferred

257
Q

Anticyclone has what

A

Low surface wind, subsidence at high troposphere

258
Q

____ forces air to rise and the surface friction prevents____

A

Divergence, Convergence

259
Q

An air mass that is warm, extremely Low relative humidity, lapse rate greater than DALR, what kind of air mass is that

A

Tropical continental

260
Q

During terrestrial radiation, what is the process

A

Conduction and convection

261
Q

What is the main mechanism of orographic fog

A

Air being forced up mountain

262
Q

Why is visibility dependent on illumination from sun or moon

A

Visibility due to transparency in air

263
Q

How does surface wind and humidity affect rate of evaporation of water

A

Warm, dry, high wind speed, Low atmospheric pressure increases the rate

264
Q

Orographic lifting: How does it occur

A

Only when wind blows more or less at right angles

265
Q

When will clear ice form on airframe

A

Clouds consisting of mainly of large supercooled water droplets at temperature 0degC to -20degC

266
Q

Polar front jetstreams occur at

A

45-65

267
Q

When is subtropical jetstream the strongest

A

During winter

268
Q

Which of these conditions are most favourable for formation of TRS

A

High relatively humidity, convergence at lower levels and divergence at the top

269
Q

Jetstreams usually have the following similar characteristics

A

A strong horizontal temp gradient, and located near a large difference in the tropopause height

270
Q

What is the visibility in fog

A

Less than 1000m

271
Q

Which of these is a correct RVR reading

A

R05 / 800D

272
Q

Initial stage of thunderstorm characterised by updraughts causing condensation

A

Releasing latent heat, making cloud warmer than surrounding areas, and making it grow stronger

273
Q

What is the main cause for Long line of weather along the ITCZ

A

Convergence of NE&SE tradewinds

274
Q

ITCZ convective clouds formed by what

A

Convergence of tradewinds

275
Q

In the Southern Hemisphere, tradewinds tend to blow from

A

SE

276
Q

Trade winds blow from

A

Sub tropical high pressure belt

277
Q

How are hails formed

A

Strong updraughts in CB

278
Q

The movement of quasi-stationary front is

A

No movement across warm and cold front

279
Q

The warm or cold front labelled on weather map takes reference from

A

Separation between air mass at the surface

280
Q

Where can mid-latitude climate zone be found

A

Western region of continent between 40-60 degrees

281
Q

What is the QFE definition based on ICAO

A

Airfield pressure

282
Q

The Sumatra Squall in Southeast Asia occurs during

A

SW monsoon, May-Aug

283
Q

Who is responsible for global weather and upper wind charts

A

WAFC

284
Q

What is zero kelvin equivalent to degree Celsius

A

-273

285
Q

Low level turbulent wind and its associated clouds are

A

Stratus

286
Q

Refer to figure above. With reference to the diurnal variation of temp over 24hours, what is the time at the point marked below

(Looks like a sound wave diagrams)

A

Early evening

287
Q

In tropics, frequent thunderstorms that occur in the afternoon, all year round, is known as

A

Heat (Thermal) thunderstorm

288
Q

An aircraft is set to SPS. Airfield is 1000ft AMSL with QNH at airfield of 1020hPa. Surface temp is 15degC. What will the altimeter read when the aircraft is on the ground at the airfield

A

890ft

289
Q

What is the minimum speed required for a moving air mass to be considered a jetstream

A

60kts

290
Q

How is the wet bulb temp at saturation related to the dew point

A

Equals to

291
Q

Refer to figure above. An airplane is taking off in the direction of a thunderstorm as shown below. The flight path is labelled by the red line. Describe the wind experienced by the airplane at stages 1, 2 and 3 of the path

(Sibei complicated drawing with clouds)

A

Headwind, Windshear and turbulence, tailwind

292
Q

Why do you reset altimeter

A

Reads pressure, therefore changes with sea level

293
Q

How do you get supercooled water droplets

A

Orographic lifting of an air mass past the 0deg isotherm causes water droplets to become supercooled

294
Q

SW monsoon in India will result in what weather

A

Cloudiness + Heavy precipitation

295
Q

What are the typical weather conditions in SW monsoon

A

Intense instability, severe weather

296
Q

Tradewinds absorb a lot of water over warm equatorial oceans and

A

Become “rain bearing” winds

297
Q

In mid latitudes, what are altocumulus made of

A

Both supercooled water droplets and ice crystals

298
Q

What is DALR

A

3deg/1000ft

299
Q

RVR measured by

A

Transmissometer

300
Q

Aircraft is departing an airfield in the SH and intends to fly through the friction level, what does he encounter

A

A speed up by 50% and backing by 30deg

301
Q

A parcel of air has water content of 4g/kg. The air can be saturated to 5g/kg. What is the relative humidity

A

80%

302
Q

A chart contains contour lines of equal height. The line is

A

Isohypse (same heights)

303
Q

There is a depression with a cold core, the pressure level

A

Pressure level bulges down, system weakens with altitude

304
Q

What does an observer on ground notice when a thunderstorm is inside a thick cloud/Cb in embedded clouds

A

Hail

305
Q

Clear ice is typically formed with what kind of cloud form

A

Cumuliform

306
Q

Updraughts in thunderstorm is usually

A

In growing stage

307
Q

Hot and humid morning in the tropics

A

Thunderstorm in the afternoon if moisture is spread out and ELR is favourable

308
Q

Polar jetstream is found at ___ of the tropopause high and ____ of the polar front

A

Equatorial ; Polar

309
Q

Direction of Tropical revolving thunderstorm in is lifetime?

Diagram that has 2 halves, bottom half looks like spider web

A

Away from equator, westwards

310
Q

As air temp rises, cloud base would

A

Rise

311
Q

____ due to pressure loft, surface friction decreases ___ . This lowers the mean sea pressure

A

Divergence ; convergence

312
Q

The fastest winds of a TRS (SH) are found

A

Around The Eye

313
Q

In a Low pressure system, ____ is aloft and friction will slow the rate of ____ of the air below

A

Divergence ; Convergence

314
Q

What cloud is icing the least likely

A

Cirrus

315
Q

When will thunderstorms occur

A

Thunderstorms will occur in the afternoon provided that moisture content and lapse rate are favourable

316
Q

What is an AIRMET

A

Weather message for Low level hazardous conditions

317
Q

Air which is warm, Low relative humidity and ELR higher than DALR

A

Tropical continental

318
Q

Warm front is likely to develop when

A

Warm air replaces cold air

319
Q

Define Saturated vapour pressure

A

Pressure of water vapour above a surface of water

320
Q

Definition of Monsoon wind

A

Rain bearing wind over Asian continent

321
Q

Pressure altitude is ____ true altitude

A

Imaginary Datum, MSL

322
Q

Which is the best description for a SW monsoon over South Asia in summer

A

Large scale sea Breeze bring heavy precipitation/shower

323
Q

When flying over near a TS where is the most severe icing

A

6-8000ft above freezing level

324
Q

Contour line on chart is based on

A

Pressure alt AMSL and sea level pressure, based on Atmospheric Temp

325
Q

Flying behind a cold front

A

Cumulus cloud, poor vis

326
Q

Polar jetstream is located on the ____ of the tropopause break and the ___ of the polar front

A

Equatorial side ; polar side

327
Q

The stage of the thunderstorm which contains only downdraft

A

Mature

328
Q

What is friction layer

A

The layer of air near earth surface which is due to the roughness of the surface

329
Q

4 stages of TRS

A

Convergence of wind along equatorial region -> smth -> TRS

330
Q

The tropopause is at its

A

Highest in equatorial region and its temp is the coldest

331
Q

Air mass in Antarctica is what kind

A

Artic continental

332
Q

Inversion layer

A

Vis better above, temp increases with height

333
Q

5 stages of TRS

A

Tropical disturbance, depression, storm, severe storm, TRS

334
Q

What is convection

A

Air warmed by forest fires

335
Q

Which is anticyclone

A

Cold cove

336
Q

Altocumulus at mid level

A

Ice + water droplet

337
Q

What’s the wind velocity at F310 165E? Data retrieved is 28052M47

A

280deg true, 52kts

338
Q

What’s the kind of precipitation in NS

A

Steady… continuous rain

339
Q

Air is descending adiabatically

A

Density decreases, temp increases

340
Q

What is the relative humidity in cloud

A

100%

341
Q

Can advection fog form over land

A

Yes - if lower atmosphere is stable

342
Q

On weather map, diff in height for diff pressure level is called

A

Isohypes

343
Q

A weather phenomenon that occurs predominantly around the coastline caused by unequal heating or cooling during day and night is called

A

Land Breeze which will occur during the day, because of rapid cooling of the land and the sea cool slower

344
Q

What is mistral

A

Strong valley winds

345
Q

Evaporation over a lake is greatest with

A

Strong & dry wind

346
Q

Where is polar jet found

A

300hPa and bending is common

347
Q

At the same alt, a parcel of air at 30degC compared to 10degC, which can hold ____ water vapour

A

More

348
Q

NS gives

A

Steady moderate to heavy rain

349
Q

RH is

A

Amount of water vapour the air can hold at its current temp

350
Q

Ice forms on

A

Leading edge of tailplanes/aerials

351
Q

Moist air less dense than dry air. True or false

A

True. Because water has a lower molecular weight than dry air. Therefore if you add water into dry air, it will reduce its mass and becomes less dense…

352
Q

A parcel of saturated air is rising adiabatically

A

It will cool at 1.5deg per 1000ft

353
Q

What is saturated vapour pressure

A

Partial pressure of water vapour

354
Q

What best illustrate convection

A

A bubble of warm air by large scale burning, rises forming cloud

Banks (5 decks)

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