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Module 1 > Meteorology > Flashcards

Meteorology Flashcards

1
Q

Most visible weather phenomenon occurs in the _____

A

Troposphere

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2
Q

The troposphere goes from ___ up to ~___ also known as the _____

A

MSL (mean sea level)
~11km (36,090ft)
Tropopause

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3
Q

Temparature decreases at a rate of ___ per 1,000ft (__ per 100m) up to a hight of ___. This is known as the _____ _____

A

1.98°C
0.65°C
Lapse rate

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4
Q

___ of water vapour is in the troposphere

A

90%

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5
Q

___ of total mass of air is in the troposphere

A

75%

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6
Q

ISA Sea level pressure

A

1013.25Hpa
29.92InHg
760mmHg

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7
Q

ISA Sea level temp

A

+15°C

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8
Q

ISA Density

A

1.225Kg/m³

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9
Q

ISA temp 11-20km (36,090 - 65,000ft)

A

-56.5°C

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10
Q

The composition of air:

A

78% Nitrogen
21% Oxygen
1% Other Gases

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11
Q

The closer to the poles you are, the _____ the tropopause, at an altitude of aprox. __ -__km

A

Lower

8 - 10km

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12
Q

The closer to the equator you are, the _____ the tropopause, at an altitude of aprox. __ - __km

A

Higher

16 - 18km

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13
Q

The closer to the poles you are, the _____ temperature is at the tropopause, aprox. __ to __°C

A

Higher

-40 to -50°C

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14
Q

The closer to the equator you are, the _____ temperature is at the tropopause, aprox. __°C

A

Lower

-75°C

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15
Q

Summer tropopause height at Latitude 30°

A

16km (52,000ft)

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16
Q

Winter tropopause height at Latitude 30°

A

16km (52,000ft)

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17
Q

Summer tropopause height at Latitude 50°

A

12km (38,000ft)

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18
Q

Winter tropopause height at Latitude 50°

A

9km (29.00ft)

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19
Q

Summer tropopause height at Latitude 70°

A

9km (29,000ft)

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20
Q

Winter tropopause height at Latitude 70°

A

8km (26,000ft)

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21
Q

Folds in the tropopause are due to

A

large air masses

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22
Q

ISA = __ - ((Alt/__) x _)

A

ISA = 15 - ((Alt/1000) x 2

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23
Q

If the actual temperature is warmer than ISA, the deviation is _____

A

Positive

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24
Q

If the actual temperature is colder than ISA, the deviation is _____

A

Negative

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25
Q

The Stratosphere extends from the _____ , up to

about ___

A

Tropopause

50km (164,040ft)

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26
Q

The Stratosphere holds __ of the atmospheres gases

A

19%

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27
Q

The Stratosphere contains the_____ ______, at __ - __km

A

Ozone layer

15 - 35km (49,200 - 114,829ft)

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28
Q

The ozone layer _____ UV radiation and emits _____ _____ _____

A

Absorbs

Long wave radiation

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29
Q

Between 20km and the stratopause, temperature _____ to __

A

Rises

0°C

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30
Q

The _____ is between the stratopause and __ - __km

A

Mesosphere

80 - 90km (262,470 - 295,280ft)

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31
Q

You can find ____ but not _____ in the lower stratosphere

A

Clouds

Turbulence

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32
Q

The _____ between the stratopause and the mesopause falls from __ to __

A

Temperature

0°C to -90°C

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33
Q

Above the mesopause, you will find the _____ which reaches a height of aprox. ___

A

Thermosphere

700km

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34
Q

Temperature in the thermosphere _____

A

Increases

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35
Q

In the thermosphere, you will find the _____ between aprox. ___ - ___

A

Ionosphere

85 - 600km

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36
Q

Potential difference (v) between the Earths surface and Ionosphere is ___ - ___

A

250 - 500kv

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37
Q

°C to °F

A

(°C x 1.8) + 32

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38
Q

°F to °C

A

(°F - 32) / 1.8

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39
Q

°C to K

A

+273

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40
Q

°F boiling point

A

212°F

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41
Q

°F freezing point

A

32°F

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42
Q

K boiling point

A

373k

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43
Q

A _____ records temperature over time and plots it on a graph

A

thermograph

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44
Q

A _____ _____ records surface temperature and humidity, must be placed __ - __ _________

A

Stevenson Screen

1 - 2m above the ground.

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45
Q

A radiosonde records 3 things:

every __

A

Air temperature
Humidity
Pressure
1.3 seconds

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46
Q

A radiosonde can reach a hight of ___

A

35km

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47
Q

Insolation

A

Amount of solar radiation absorbed per unit area over time

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48
Q

The Earth is tilted on an axis of

A

23.5°

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49
Q

In January, the Earth is _____ from the sun

A

91 million miles

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50
Q

In July , the Earth is _____ from the sun

A

95 million miles

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51
Q

The earth spins

A

anti-clockwise

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52
Q

Summer solstice

A

21st June, Northern hemisphere closest to the sun at 23.5°N - the tropic of cancer

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53
Q

Winter solstice

A

21st December, Southern hemisphere closest to the sun at 23.5°S - the tropic of Capricorn

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54
Q

Spring & Autumn Equinox

A

23rd March & 23rd September, Sun at same angle as equator.

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55
Q

Conduction

A

The transfer of heat by physical contact

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56
Q

Convection

A

The transfer of heat through the vertical

movement of air

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57
Q

Advection

A

The transfer of heat through the horizontal movement of air

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58
Q

Sublimation

A

Direct change of a vapour to solid, or solid to vapour

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59
Q

In the day, thick cloud = _____. No cloud = _____

A

Cooler

Warmer

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60
Q

At night, thick cloud = _____. No cloud = _____

A

Warmer

Cooler

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61
Q

Inversion

A

Temperature increasing with height

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62
Q

In the day, wind = _____. No wind = _____.

A

Cooler

Warmer

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63
Q

At night, wind = _____. No wind = _____.

A

Warmer

Cooler

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64
Q

_____ reduces non-linearly with height, due to the _____ distribution of the mass of air

A

Pressure

Non-linear

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65
Q

Colder then ISA, the _____ dense the air

A

More

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66
Q

Warmer the ISA, the _____ dense the air

A

Less

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67
Q

Natural inversions

A

form over night

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68
Q

Fog is caused by the temperature _____ enough to condense the _____ _____ into _____ _____

A

Cooling
Water vapour
Water droplets

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69
Q

At the bottom of a valley, visibility can be _____ and aircraft performance is _____ due to _____ air.

A

Poor
Better
Denser

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70
Q

When air is subsiding and diverging it is a _________

A

High pressure system

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71
Q

The greater the _____ of overlying air, the _____ the atmospheric pressure

A

Mass

Greater

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72
Q

Pressure reduces by ___ per ___ up to ____

A

1hPa
27ft (8m)
20,000ft

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73
Q

Low pressure areas are known as

A

Depressions (lows)

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74
Q

High pressure areas are known as

A

Anticyclones (highs)

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75
Q

Whenever a pressure variation exists, the _____ created driving the air from high to low _____ is called the ________

A

Force
Pressure
Pressure gradient force (PGF)

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76
Q

The PGF is the _____ _____ driving the flow of air and _____ the wind speed

A

Primary force

Determines

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77
Q

Trough lines

A

Areas of disturbances

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78
Q

Barometric pressure can be measured by 2 devices:

A

A mercury Barometer

A Aneroid Barometer

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79
Q

What is the QFE?

A

The isobaric surface pressure at the airfield reference point

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80
Q

What is the QNH?

A

The barometric pressure measured at the reporting stating which has be mathematically adjusted to MSL using the airfields elevation.

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81
Q

QNH = ___ +- (Elevation/___)

A

QNH = QFE +- (Elevation/27ft or 8m)

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82
Q

There is a __ height difference for every __ of ISA deviation

A

4%

10°C

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83
Q

Height

A

The indication above ground level, normally the height above an aerodrome QFE reference point.

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84
Q

Altitude

A

The indication above MSL

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85
Q

Flight levels use the pressure setting of

A

Mean Sea Level (1013pHa)

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86
Q

When the altimeter is indicating a reading lower than the true altitude it is

A

Over reading

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87
Q

When the altimeter is indicating a reading heigher than the true altitude it is

A

Under-reading

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88
Q

Cold air: _____ altitude < _____ altitude

A

True

Indicated

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89
Q

Warm air: _____ altitude < _____ altitude

A

Indicated

True

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90
Q

The barometric lapse rate

A

27ft per 1hpa

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91
Q

To determine the IA change use the equation

A

IA change (ft) = Difference in hPa x 27ft

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92
Q

Most dangerous - “____ to ____, look out below”

A

High

Low

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93
Q

Most dangerous - “____ to ____, don’t be bold”

A

Hot

Cold

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94
Q

Equation to calculate Temperature Error Correction

A

((ISA Devation/10) x 0.04) x altitude

OR

(4 x (Altitude/1000)) x ISA devation

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95
Q

Equation to calculate ISA Deviation

A

15 - ((alt/1000) x 2)

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96
Q

If an aerodrome elevation is given in the question

A

It must be taken into account

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97
Q

Due to the _____ effect, _____ occurs over the crest of high terrain, causing air speed to _____, and _____ and _____ to decrease.

A 
Venturi 
Convergence 
Increase
Pressure
Temperature
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98
Q

In controlled airspace, controllers assign levels to ___ flights to provide _____ _____.

A

IFR

Terrain Clearance

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99
Q

Controllers have no responsibility for the _____ _____ for ____ aircraft.

A

Terrain Clearance

VFR

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100
Q

In temperatures warmer than ___, FL separation _____

A

ISA

Increases

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101
Q

In temperatures colder than ISA, FL separation _____

A

Decreases

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102
Q

What is the definition of Density ? And what is ISA density at sea level

A

Measure of a mass of air within a given volume.

1.225 Kg/ m3

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103
Q

Under ISA, 1/2 and 1/4 of MSL density occurs at what altitude?

A

22000 FT and 40000 FT

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104
Q

Density in the atmosphere is affected by

A

Pressure
Temperature
Humidity

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105
Q

The density decreases with altitude, but at a ______-______ rate. It reduces more quickly at ________ altitudes. Mimicking the pressure lapse rate with height.

A

Non-linear

Lower

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106
Q

What are the 4 main steps of the hydrological cycle

A

Evaporation, Condensation, Precipitation, Run-off

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107
Q

On average there’s approx. ___% of water vapour in the atmosphere. But it can vary from 0 to ___% . 90% of the water vapour is found in the __________

A

1, 5, troposphere

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108
Q

Humidity mixing ration tells you how much water vapour is actually in the air, it is measured in ____ of water vapour per ____ of dry air

A

Grams, Kilograms

g/Kg

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109
Q

Humidity mixing ratio won’t change unless……

A

You add/ remove water vapour

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110
Q

Saturation mixing ratio is the ______ amount of water vapour that can be in the air for a given temperature

A

Maximum

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111
Q

Warmer air can potentially ‘______’ more water vapour than colder air

A

Hold

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112
Q

Saturation mixing ratio ______ with increasing altitude and decreasing temperature. Whereas humidity mixing ratio ______ ______ constant as altitude increase and pressure and temperature decrease

A

Decrease

Stays constant

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113
Q

The ratio between the amount of water vapour that the air is holding and the maximum amount of water vapour that air can hold is called?

A

Relative humidity

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114
Q

At constant pressure, relative humidity is affected by……

A

Amount of water vapour

Temperature

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115
Q

Assuming pressure is constant throughout a clear day, what is the RH like to be _______ 30 mins after sunrise and ______ 2-3 hours after noon.

A

Greatest

Least

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116
Q

The close the ambient air temperature is to the ______ ______ temperature, the higher the humidity

A

Dew point

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117
Q

Formulas for relative humidity, using temperature and dew point

A

RH % = 100 - (5x (T - Td))

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118
Q

% difference between the dry bulb temperature and wet bulb temperature is equal to?

A

Relative Humidity

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119
Q

What is the DALR?

How does it change with height?

A

Dry adiabatic lapse rate

3 degrees per 1000 FT/ 1 degree per 100 m

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120
Q

What is SALR?

And how does the temperature vary with height?

A

Saturated adiabatic lapse rate

1.8 degrees per 1000 FT / 0.6 degrees per 100 m

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121
Q

A parcel of saturated or dry air is said to ________ ________ if it is cooler than the environment. it will sink back down to its original level even when forced to rise

A

Absolutely stable

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122
Q

ISA ELR is?

A

2 degrees per 1000 FT / 0.65 degrees per 100 m

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123
Q

When an air parcel is rising and subsiding along the saturated adiabatic lapse rate, the RH must ______ ______, until ______ ______ is removed from the parcel.

A

Remain constant (at 100%).

Water vapour

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124
Q

The ______ the saturated air, the ______ it cools, because warmer saturated air holds ______ moisture than cold saturated air,
therefore ______ condensation will take place when it is cooled, but more ______ ______ will also be released.

A

Warmer, slower, more, more, latent heat

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125
Q

The SALR increases ______ with height

A

Exponentially

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126
Q

Low pressure systems are known as

A

Cyclones or depressions

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127
Q

Low pressure are always accompanied by _____ and _____

A

Cloud

Precipitation

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128
Q

Low pressure systems have isobars that are _____ _____ than other systems.

A

Closer together

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129
Q

In Low pressure systems, air flows _____ in the Northern Hemisphere and _____ in the Southern Hemisphere

A

Anti-clockwise

Clockwise

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130
Q

As air rises, it _____, causing water vapour to _____ and _____ _____ with possible _____

A

Cools
Condense
Form clouds
Precipitation

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131
Q

With your back to the wind in the Northern Hemisphere, the low pressure system is to your _____

A

Left

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132
Q

Small scale low pressure systems can be ___ to ___NM across and usually occur over _____

A

1 to 20NM

Land

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133
Q

Large scale low pressure systems can be ___ to ___NM across

A

300 to 1000+NM

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134
Q

Small scale warm, lows can _____ during the day over land masses in _____.

A

Develop

Summer

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135
Q

Warm lows are low pressure systems in which the _____ is _____ than the surrounding environment

A

Core

Warmer

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136
Q

Warm lows can produce 3 things:

A

Heavy rain
Thunder Storms
Flash Floods

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137
Q

Large thermal lows usually form over land in summer where the _____ is present

A

Inter-tropical Convergence Zone (ITCZ)

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138
Q

In July the ITCZ is in the _____ hemisphere and ranges from latitudes ___ to ___

A

Northern

15-20°N

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139
Q

In January the ITCZ is in the _____ hemisphere and ranges from latitudes ___ to ___

A

Southern

0-20°S

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140
Q

When the ITCZ moves it affects local _____ _____ and has a large effect on the _____

A

Tropical winds

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141
Q

Inland Water warm depressions can form over _____ in winter, when colder air over _____, moves over warmer _____ or _____.

A

Water
Continents
Seas
Lakes

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142
Q

Small but intense maritime meso-scale cyclones that form in in winter, by cold polar or arctic air advected over relatively warmer water.

A

Polar lows

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143
Q

Low pressure systems in which the entire core is colder than the surrounding environment

A

Cold lows

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144
Q

Cold lows can produce 5 things:

A 
Snowfall
Thunderstorms 
Heavy rain 
Floods 
Windshear
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145
Q

Cold depressions are typically _____ _____ and move with medium airflow at _____ to _____ft.

A

Frontal depressions

2,000 to 3,000ft

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146
Q

A low-pressure area which forms in the lee of mountains

A

Orographic Depression

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147
Q

With a strong wind blowing at approx. ___ towards a mountain range at, the wind will tend to blow _____ ___ _____ of the mountain rather than _____ ___ _____

A

90°
Around the side
Over the top

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148
Q

Isobaric troughs indicate

A

An area of low pressure going into another system

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149
Q

Trough lines indicate

A

Areas of stronger surface convergence

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150
Q

High pressure systems are also known as

A

Anticyclones

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151
Q

An anticyclone is

A

an area of relatively high surface pressure.

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152
Q

Air is _____ in a high pressure system

A

Subsiding

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153
Q

As the air _____ it warms due to _____ and so cloud formation is _____, causing the weather to usually be settled with only _____ amounts of cloud cover

A

Subsides
Compression
Inhibited
Small

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154
Q

High pressure systems can be up to ____NM and are _____ _____ _____

A

1500NM

Slow moving systems (quasi-stationary)

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155
Q

Warm highs

A

High pressure systems in which the entire core is warmer than the surrounding environment

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156
Q

Pressure levels are pushed _____ in the core due to excess air in the upper troposphere as the warm air _____

A

Higher

Rises

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157
Q

Warm High pressure systems can produce 4 things:

A

Heatwaves
Drought
Poor air quality
High pollen count

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158
Q

High pressure areas are associated with _____ _____

A

Light winds

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159
Q

High pressure systems usually occur around

A

30°N/S

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160
Q

Cold highs

A

High pressure systems in which the entire core is colder than the surrounding environment

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161
Q

In high pressure systems air flows _____ in the Northern Hemisphere and _____ in the Southern Hemisphere

A

Clockwise

Anticlockwise

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162
Q

Due to the colder, _____ air, the pressure levels bulge _____ at higher altitudes

A

Heavier

Downwards

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163
Q

Cold High pressure systems can produce 6 things:

A 
Droughts
Frosts
Snowfall 
Mist/Fog
Low level cloud
Poor air quality
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164
Q

Cold anticyclones are permanently found over the _____ know as _____ _____.

A

Poles

Polar Highs

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165
Q

Blocking high

A

Highs that can become stronger in summer, pushing lows around them

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166
Q

Blocking highs are _____ and between __ and __

A

Quasi-stationary

50° and 70°

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167
Q

Ridges are indicated by _____ extending out from the area of _____ pressure

A

Isobars

High

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168
Q

Cols

A

An area of relatively high pressure shown on a synoptic chart, situated between two areas of higher pressure and low pressure

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169
Q

Flat-Pressure Patterns

A

An area clear of isobars

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170
Q

The 3 cells from the poles to the equator

A

Polar cell
Ferrell cell
Hadley cell

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171
Q

The polar cell ranges from the latitudes ___ and ___

A

90°

60°

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172
Q

The Ferrell cell ranges from the latitudes ___ and ___

A

60°

30°

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173
Q

The Hadley cell ranges from the latitudes ___ and ___

A

30°

0°

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174
Q

At 90° you can find _____ pressure

A

High

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175
Q

At 60° you can find _____ pressure

A

Low

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176
Q

At 30° you can find _____ pressure

A

High

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177
Q

At 0° you can find _____ pressure

A

Low

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178
Q

Warm high pressure regions:

A

Azores high, 1020hPa, (all year)

Pacific high, 1020hPa (all year)

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179
Q

Cold high pressure regions:

A

Siberian high, 1035hPa (Jan)

Canadian high 1020hPa (Jan)

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180
Q

Warm Low pressure regions:

A

North Australian low, 1005hPa (Jan)
Asian low, 1000Hpa (July)
North American low, 1010hPa (July)

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181
Q

Cold Low pressure regions:

A

Icelandic low, 1000hPa (Jan)
Aleutian low, 1000hPa (Jan)
Icelandic low split, 1010hpa (July)

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182
Q

Density

A

Measure of a mass of air within a given volume (kg/m3 or gm/m3)

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183
Q

As altitude increases, density _____ at a _____ rate

A

Decreases

Non-linear

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184
Q

In ISA conditions atmospheric density is at 3/4 of MSL at _____, 1/2of MSL at _____ and 1/4 of MSL at _____

A

10,000ft
22,000ft
40,000ft

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185
Q

If pressure decreases, the mass of air within the same given volume _____

A

Decreases

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186
Q

More humid air is _____ _____ than than dry air

A

Less dense

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187
Q

In cold air density decreases ______ with height than warm air.

A

quicker

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188
Q

Equation for pressure difference:

A

PA diff = 120ft x ISA temp devation

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189
Q

If colder, it will be a ______ pressure difference. If warmer, it will be a _____ pressure difference.

A

Negative

Positive

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190
Q

There is __% of water vapour in the atmosphere

A

1%

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191
Q

Warm, air can hold _____ water vapour than cold air.

A

More

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192
Q

The HMR (Humidity mixing ratio) tells you:

A

How much water vapour is actually in the air measured in g/kg (or kg/kg)

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193
Q

The HMR’s value won’t change unless you _____ or _____ water vapour from the air:

A

Add

Remove

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194
Q

The MR is constant as altitude _____ and pressure and temperature _____

A

Increases

Increase

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195
Q

The SMR (Saturation mixing ratio) is:

A

the maximum amount of water vapour that can be in the air at a certain temperature, measured in g/kg (or kg/kg)

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196
Q

The SMR _____ with increasing altitude and decreasing temperature

A

Decreases

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197
Q

Relative humidity equation:

A

RH% = (HMR/SMR) x 100

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198
Q

At a constant pressure the RH is affected by the:

A

Amount of water vapour

Temprature

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199
Q

The RH is

A

The ratio (%) between the amount of water vapour that the air is holding, and the maximum amount of water vapour that the air can hold.

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200
Q

The RH is greatest ____________ and weakest ____________

A

30 mins after sunrise

2-3hrs after midday.

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201
Q

The closer the ambient air temperature to the dew point temperature, the _____ the humidity and the further away the ambient air temperature to the dew point temperature, the _____ the humidity

A

Higher

Lower

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202
Q

The dew point

A

The temperature, to which the air must be cooled for it to become saturated and start to condense

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203
Q

Equation to calculate RH with the dew point:

A

RH% = 100 - (5x (T - TD)

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204
Q

A Psychrometer is used to determine 3 things:

A

Temprature
RH%
Dew point

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205
Q

Adiabatic

A

A process that occurs without the transfer of heat or matter with the surroundings

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206
Q

DALR

A

-3°C per 1,000ft (-1°C per 100m )

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207
Q

SALR

A

-1.8°C per 1,000ft (-0.6°C per 100m)

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208
Q

In the tropics SALR can be _____ and in Polar regions it can be _____

A
  1. 4°C per 100m

0. 9°C per 100m

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209
Q

Absolute stability is when

A

ELR < Both DALR & SALR (they subside)

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210
Q

Absolute instability is when

A

ELR > Both DALR & SALR (they rise)

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211
Q

Conditional stability is when

A

DALR (Subsides) > ELR > SALR (rises)

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212
Q

Neutral Stability is when

A

ELR = DALR or ELR = SALR

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213
Q

If cooled from below, the air is _____, if warmed from below, the air is _____.

A

Stable

Unstable

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214
Q

Clouds form when the invisible water vapour in the air, _____ onto microscopic nuclei, becoming ___________ or __________

A

Condenses
Visible water droplets
Ice crystals

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215
Q

Cumulus clouds from through _____ when the atmosphere is _____

A

Convection

Unstable

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216
Q

A front is where ____________, here _____ air rises over _____ air.

A

2 air masses meet
Warmer
Colder

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217
Q

On a warm front you can find:

A

Stratus and Cirro clouds

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218
Q

On a cold front you can find:

A

Cumulus clouds

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219
Q

A cold front is _____ lifting and moves _____.

A

Steeper

Faster

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220
Q

The quicker a front is moving, the ______ _____ the uplift.

A

More instense

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221
Q

Unstable orographic uplift is when air is forces to rise by _____ and _____. The air then continues _____.

A

Mountains
Convects
Upwards

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222
Q

Stable orographic uplift is when the _____ effect takes place. _____ takes place decreasing the _____ _____. Air then _____ on the lee side.

A

Foehn
Precipitation
Dew point
Descends

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223
Q

Convergence is when

A

Two air masses coming from different directions meet and are forced to rise.

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224
Q

Turbulent layers are formed by

A

Air blowing over solid objects such are buildings, trees and hills.

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225
Q

Turbulent layers tend to form up to a depth of about

A

2,000-3,000ft

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226
Q

If the _____ _____ is reached within the turbulent layer, _____ will form at the top of the layer

A

Dew point

Cloud

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227
Q

Inversions cause an increase in _____ and _____ the upward growth of cloud by preventing further _____

A

Stability
Limit
Convection

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228
Q 
Oktas leves: 
Few - 
Scattered (SCT) - 
Broken (BKN) - 
Overcast (OVC) -
A

1 - 2
3 - 4
5 - 7
8

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229
Q

Cloud base

A

The height of the base of the cloud is measured above ground level in ft. measured by a Ceilometer

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230
Q

Cloud base equation:

A

Cloud Base Height ft = Temp. − Dew Point X 400

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231
Q

The height above the ground or water of the base of the _____ layer of cloud below _____ covering more than _____ the sky

A

Lowest
20,000ft (6,000m)
Half

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232
Q

Vertical visibility is used

A

When the sky is obscured by precipitation, and cloud details cannot be assessed but information on vertical visibility is available.

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233
Q

High level clouds: name group

A

Cirro

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234
Q

High level clouds: Polar altitudes

A

3-8km (10,000 - 25,000ft)

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235
Q

High level clouds: Temperate altitudes

A

5-13km (6,500 - 23,000ft)

236
Q

High level clouds: Tropical altitudes

A

6-18km (20,000 - 60,000ft)

237
Q

Mid level clouds: name group

A

Alto/Nimbo

238
Q

Mid level clouds: Polar altitudes

A

2-4km (6,500 - 13,000ft)

239
Q

Mid level clouds: Temperate altitudes

A

2-7km (6,500 - 23,000ft)

240
Q

Mid level clouds: Tropical altitudes

A

2-8km (6,500 - 25,000ft)

241
Q

Low level clouds: name group

A

Status/cumulo

242
Q

Low level clouds: Polar altitudes

A

0-2km (0-6,500ft)

243
Q

Low level clouds: Temperate altitudes

A

0-2km (0-6,500ft)

244
Q

Low level clouds: Tropical altitudes

A

0-2km (0-6,500ft)

245
Q

Cumulonimbus clouds can range from _____ to very _____ levels

A

Low

High

246
Q

Cirrus clouds tend to look

A

Curly/feathery/wispy

247
Q

Stratus clouds tend to look

A

Flat, wide and layered

248
Q

Nimbus clouds tend to be

A

Rain bearing

249
Q

Cumulus (Cu)

A

Base height: 1,200-6,000ft - low level
Detached, generally dense with sharp outlines
Sunlit white, base dark.
Mainly water droplets, little precipitation

250
Q

Stratocumulus (Sc)

A

Base height: 1,200-7,000ft - low level
Grey/white
Little precipitation
Composed of water droplets

251
Q

Stratus (St)

A

Base height: 0 - 1,500ft - low level
Grey cloud layer
Drizzly precipitation
low temperatures

252
Q

Cumulonimbus (CB)

A 
Base height: 1,000-5,000ft - low level 
Heavy dense cloud
Reaches extreme heights
Base dark,
water droplets + Ice crystals
Large raindrops, snow &amp; hail
253
Q

Altostratus (As)

A 
Base height: 8,000 - 17,000ft - mid level
Greyish cloud sheet
Great horizontal extent 
thin 
water droplets + ice crystals
254
Q

Nimbostratus (Ns)

A 
Base height: 1,500-10,000ft - low/mid level
Grey cloud layer 
Thick, blocks out sun
covers wide area
Great vertical extent 
Water droplets 
Produces precipitation
255
Q

Altocumulus (Ac)

A

Base height: 7,000-17,000ft - mid level
White,
small, detached but frequent
water droplets

256
Q

Cirrus (Ci)

A

Base height: 17,000-35,000ft - high level
White detached clouds
Small Ice crystals
Silky

257
Q

Cirrostatus (Cs)

A 
Base height: 17,000-35,000ft - high level
Transparent, whitish cloud
smooth appearance 
Very wide
Small Ice crystals
258
Q

Cirrocumulus (Cc)

A

Base height: 17,000-35,000ft - high level
white patch layer
grains and ripples
Ice crystals

259
Q

Species - Humilis (hum)

A

flattened, never produce precipitation

Coulds - Cu

260
Q

Species - Medicoris (med)

A

moderate vertical extent, no precipitation

Clouds - Cu

261
Q

Species - Congestus (con)

A

Strongly sprouting, great vertical extent, bulging upper part, may produce perciptation.
Clouds - Cu

262
Q

Species - Fractus (fra)

A

small, ragged edges, rapid changes

Clouds - Cu, St

263
Q

Species - Lenticaularis (len)

A

Shape of lense/almond, elongated, well defined outlines.

Clouds - Sc, Ac, Cc

264
Q

Species - Castellanus (cas)

A

turrets rising vertically, horizontal base, evident when seen from side.
Clouds - Sc, Ac, Ci

265
Q

Species - Virga

A

Trails of precipitation which does not reach earths surface, attached to under surface of cloud
Clouds - Sc, Cb, As, Ns, Ac, Cc

266
Q

Species - Calvus (cal)

A

Sprouting of upper parts are flattened, whitish mass without sharp outlines.
Clouds - CB

267
Q

Species - Capillatus (cap)

A

Upper portion is fibours/striated stucture, shape of anvil or plume. accompanied by shower/thunderstorm.
Clouds -CB

268
Q

Low base cloud types:

A

Stratus (St)
Stratocumulas (Sc)
Cumulus (Cu)
Cumulonimbus (CB)

269
Q

Middle base cloud types:

A

Altocumulus (Ac)
Altostratus (As)
Nimbostratus (Ns)

270
Q

High base cloud types:

A

Cirrrus (Ci)
Cirrocumulus (Cc)
Cirrostratus (Cs)

271
Q

When water vapour first condenses onto a _____, the water droplet has an average diameter of approx. _____

A

Nuclei

0.02mm

272
Q

The Bergeron-Finderson theory:

A
  • If parcels of air are uplifted to a sufficient height in the troposphere, the dew-point temperature will be very low, and minute ice crystals will start to form.
  • The supercooled water droplets will also freeze on contact with these ice nuclei.
  • The ice crystals subsequently combine to form larger flakes which attract more supercooled droplets.
    – This process continues until the flakes fall back towards the ground.
    – As they fall through the warmer layers of air, the ice particles melt to form raindrops
    – However, some ice pellets or snowflakes might be carried down to ground level by cold downdraughts.
273
Q

The Coalescence theory:

A
  • Applies to warm clouds
  • They contain water droplets of many differing sizes, which are swept upwards at different velocities so that they collide and combine with other droplets
    – When the droplets have a radius of approx. 3mm, their movement causes them to disintegrate, forming a fresh supply of water droplets
    – This theory allows droplets of varying sizes to be produced
274
Q

Drizzle (DZ)

A

Fine drops of water very close to one another that falls from a cloud.
Diameter 0.2-0.5mm
terminal velocity = 4m/s

275
Q

Rain (RA)

A

Precipitation of drops of water that falls from a cloud.
Diameter 0.5-0.6mm
Terminal velocity = 9m/s

276
Q

Freezing Precipitation (FZRA/FZDZ)

A

Forms ahead of warm fronts,

Starts frozen, melts, falls through air <0°C, freezes upon contact with a surface.

277
Q

Snow (SN)

A

Solid precipitation of ice crystals, singly or stuck together, that fall from a cloud.
Falls upto 2°C, heaviest when -2°-0°C
Largest flakes can be >25mm (adv. >4mm)

278
Q

Sleet

A

Melting snow or mix of rain and snow,

above 2°C

279
Q

Snow grains (SG)

A

Precipitation of very small opaque white particles of ice that falls from a cloud.
diameter <1mm
between -10°-0°C
Do not bounce

280
Q

Diamond Dust

A

Precipitation that falls from a clear sky in very small ice crystals, often so tiny that they appear to be suspended in the air.
Diameter 100μm (micrometer)

281
Q

Snow pellets

A

Precipitation of white and opaque ice particles that falls from a cloud.
Diameter <5mm
Brittle, easily crushed
Bounce when hit ground

282
Q

Small Hail (GS)

A

Diameter <5mm

283
Q

Hail (GR)

A 
Hailstones form when a nucleus, collects cloud droplets or drops of rain as it repeatedly rises and falls, through a cloud
From CB clouds
Can be found up to 45,000ft
as large as 100mm at 10,000ft
Diameter 5-50mm
284
Q

Ice Pellets (PL)

A

Precipitation of transparent ice particles that falls from a cloud.
They fall into a sub-cloud layer of warm air where the snowflakes melt or partially melt, and then fall into a cold layer of air, where they freeze and reach the ground as frozen precipitation
Diameter <5mm
Bounce when hity the ground

285
Q

Light: DZ, RA and SN

A

N/A,
<2mm/hr,
<0.5cm/hr

286
Q

Moderate: DZ, RA and SN

A

Some run-off,
2-10mm/hr
0.5-4cm/hr

287
Q

Heavy: DZ, RA and SN

A

> 1mm/hr
10mm/hr
4cm/hr

288
Q

Continuous -

A

Lasts over 1 hour

289
Q

Intermittent -

A

Continuous with breaks

290
Q

Showers -

A

Short lived

291
Q

The 3 fundamental requirements for thunderstorms

A

Instability at least 10,000ft above the freezing level
An adequate supply of moisture
A trigger to start uplift

292
Q

Air movement that can cause thunderstorms:

A

Convective
Frontal
Orographic
Convergence

293
Q

Features of a Convective TS:

A

Uplift trigger is usually thermal uplift cause by surface warming.
Most common in summer
Maximum in the early afternoon
Most server TS

294
Q

Features of a frontal TS:

A 
Occur where a cold air mass undercuts a warm air
mass and forces it upwards
Ahead of the cold front 
More common in winter 
Fastest moving TS
295
Q

Orographic TS formation:

A

Orographic convection forms large CB clouds due to unstable air accelerating the convection process

296
Q

Single cell TS are made up of a single _____ cloud, that develops into a _____ and then into a _____ before dying away.

A

CU
CB
Thunderstorm

297
Q

Features of single cell TS:

A

Small
Brief
Weak
Grow and start to die within an hour

298
Q

The initial stage of single cells has updraughts of around _____, it is fed with _____ _____ _____ and can reach the tropopause. This stage lasts _____

A

30m/s, 60kts, 5000-6000ft/min
Warm moist air
15 - 20 mins

299
Q

The mature stage of single cell TS, updraft are now at _____ and downdrafts are caused by _____ and reach approx. _____. This stage can last _____

A

50m/s, 100kts, 10,000ft/min
Precipitation
2,000ft/min
15-30mins

300
Q

The 9 hazards of a TS:

A 
Rain
Hail
Ice
Turbulence
Windshear
Lightning
Static electricity
Pressure
Visibility
301
Q

When rain strikes the aircraft is has a _____ and _____ momentum. It can also cause a _____ moment if it impacts unevenly.

A

Downward
Rearward
Pitching

302
Q

Rain increases the airframe’s _____ and produce _____

A

Mass

Drag

303
Q

Turbine engines have a limit on the amount of ______ they can ingest.

A

Water

304
Q

+RA can cause pressure sensing ____________

A

Instrument errors

305
Q

It should always be assumed that where there’s a thunderstorm, there is _____.

A

Hail

306
Q

The higher the ______ _____, and the ______ the moisture content of the air mass, the stronger the convective activity and the damaging hail.

A

Lapse rate

Greater

307
Q

Airframe ice is likely in cloud or rain at a temperatures below _____

A

0°C

308
Q

You can get ______ turbulence inside CB & TS

A

MOD - SEV

309
Q

Clear Air Turbulence (CAT), occurs __________.

Severe turbulence can also be encountered several thousand feet _____ active thunderstorm clouds

A

Outside the cloud

Above

310
Q

Windshear conditions occur with thunderstorms where there are _____ _____. As the cold downdrafts reach the ground, the air is forced to spread out, up to _____ ahead of the TS and up to _____. Can reach speeds of _____ changing at _____.

A 
Gust fronts 
25-30km
6000ft
80kts
90°
311
Q

Windshear can be indicated by _____ clouds or _____ clouds.

A

Shelf

Roll

312
Q

Downbursts

A

Highly concentrated and powerful downdraughts

of air caused by precipitation at the top of the cloud, drawing cold, dense down with it as it falls.

313
Q

Microbursts:

A

3,000-4,000ft/min
Less than 5 mins
Less than 5km across

314
Q

Macrobursts:

A

More than 5 mins
More than 5km across
As high as 11,800ft

315
Q

Wet Microburst / Macrobursts:

A

Downdraft from a Micro/Macroburst is started by
precipitation and is often marked by a column of
+RA

316
Q

Dry Microburst / Macrobursts:

A

If the air below the cloud base is dryer, the rain can
evaporate. Evaporation will cool the descending air,
making it denser and even more powerful

317
Q

Lightning is a sudden _____ _____ on a large scale. Caused by _____ and _____ water droplets producing a build up of _____ _____.

A

Electrical discharge
Rising
Falling
Static electricity

318
Q

Lighting discharges at a heat of _____ and travels up to _____ with a current around _____

A

5000K
140,000mph
30,000Amps

319
Q

Lighting can cause:

A

Holes in the airframe
Temporary blindness
Noise Induced Hearing Loss
Errors with instruments

320
Q

_____ _____ is another form of electrical discharge and it appears as a _____ glow around the windscreens and external parts of the aircraft. A high voltage differential of min _____ required

A

St Elmo’s fire
Blue/violet
100kv

321
Q

St Elmo’s fire can cause:

A

Very occasionally cracked windscreens
Errors with navigational aids such as ADF
Noise on high and medium frequency radio bands

322
Q

Dissipating is where:

A

Down draughts becoming stronger than the updrafts.

The cloud base rises due to adiabatic warming of sinking air, causing evaporation and the cloud can spread into Sc/St

323
Q

Multi-cell thunderstorms are more_____ than single cell. New updrafts form along the _____ _____ of rain cooled air. Individual cells usually last ______ , while the whole system can last _____.

A

Common
Leading edge
30-60 mins
Hours

324
Q

The weather Multi-cell’s produce is _____ _____ than a single-cell

A

More severe

325
Q

Squall lines can be _____ _____ long but only _____ wide. The gust fronts can be felt _____ ahead.

A

Hundreds of miles
16-32km
50-60km

326
Q

Mid-latitude squall lines:

A

Usually form in the warm air mass, ahead of & parallel to the cold front
Tend to move from west to east with the westerly situations
Tend to pass quickly with the cold front
Most common over large continental areas,

327
Q

Tropical squall lines:

A

Structurally very similar to mid-latitude squall lines, but because the tropopause is higher in the tropics, they are generally taller
Tend to move from east to west with the Trade Winds
Most last 1-2 days
GR rarely occurs due to the warmer tropical air masses

328
Q

Mesoscale Convective System (MCS):

A

Collection of thunderstorms that act as a system and they can last more than 12 hours (normally 1-2 days)

329
Q

They can be round or linear in shape, and include systems such as:

A

Tropical storms
Squall lines
Polar lows
Mesoscale convective complexes

330
Q

Supercells are the _____ common type of TS, but have the _____ severe weather. They can last for _____

A

Least
Most
Hours

331
Q

Supercells have a contains a deep and persistent rotating updraft (approx. 8000-10,000fpm), called a _____

A

Mesocyclone

332
Q

Single cells need:

A

Moderate to strong speed and directional wind shear between the surface up to about 20,000ft

333
Q

‘A tornado is a _____, violently _____ column of air that extends from the base of a _____ to the ground’

A

Narrow
Rotating
Thunderstorm

334
Q

They are the _____ _____ of all atmospheric storms

A

Most violent

335
Q

Tornadoes are most likely in __________ and occur between the times _____

A

Late Spring/early Summer

16:00 - 21:00

336
Q

Once a TS has formed, if the winds increase strongly with height, the TS updraught may begin to _____. Downdraughts within the supercell storm help to concentrate the rotation and to bring it down
to ______ ______.

A

Rotate

Lower levels

337
Q

Speed of a tornado’s horizontal movement:

A

20-40kts

338
Q

Wind speeds in funnel:

A

200kts

339
Q

Life span:

A

up to 30mins

340
Q

Average diameter:

A

100-150m

341
Q

Water spouts are:

A

Tornadoes over water

342
Q

Tornadoes are measured on the _____ scale which is based on the funnel wind speed and damage it incurs.

A

Fujita

343
Q

A Funnel Cloud:

A

This is a rotating column of air, often a violent whirlwind, indicated by the presence of an inverted cone-shaped cloud, extending downwards from the base of a Cb, but not necessarily reaching the surface.

344
Q

You can anticipate each type of thunderstorm through what 4 things:

A

Pre-flight weather briefs
Observation in flight
Meteorological information (charts, reports, etc.)
Information given by ground and airborne weather radar

345
Q

If using weather radar avoid the thunderstorm by:

A

Below 20,000ft - 10NM

Above 20,000ft - 20NM

346
Q

In VFR or no radar available, avoid TS by at least

A

10 miles

347
Q

Dust devils:

A

Small, rotating columns of air that occur when one piece of ground heats up faster than the ground surrounding it on a hot, calm, dry day

348
Q

Dust devils have an average height of _____ and width of about _____

A

650ft

10-100ft

349
Q

Tropical revolving storms must have oceans with a temp. of ______ and are at least _____ deep.

A

26.5°C

50m

350
Q

TRS cannot form within ___ of the equator and usually form between the latitudes of _____

A

5°

10 - 20°

351
Q

The 4 stages of TRS development:

A

Tropical disturbance
Tropical depression
Tropical storm
Tropical Revolving storm

352
Q

Tropical disturbance:

A

A discrete tropical weather system of apparently organized convection - generally 200-600km (100-300NM) in diameter

353
Q

Tropical depression

A

The maximum sustained wind speed is up to 33kts

Depressions have a closed circulation.

354
Q

Tropical storm

A

The maximum sustained surface wind
speed ranges from 34kts to 63kts
Convection is more concentrated near the center

355
Q

Tropical Revolving storm:

A 
Windspeeds >64kts
eye is 20-50km in diameter
Fastest winds are at the "eye wall" - up to 175kts
Vertical winds up to 43kts
averiging 500km in diameter
356
Q

The wind speeds are the top speeds sustained for at least _____ at _____ above the surface and are compares to the _____ Scale

A

1min
10m
Beaufort

357
Q

TRS travel:

A

<15kts

East to West and then curve Northwards, away from the Equator, before turning East again

358
Q

Hurricanes:

A

North America

May - Nov

359
Q

Cyclones:

A

Central Asia + Oceania
N. Hemisphere: Apr - Dec
S. Hemisphere: Oct - May

360
Q

Typhoons:

A

East Asia

April - Jan

361
Q

Easterly Waves

A 
Generated by an instability in the African Easterly Jetstream, causing troughs to extend out and away from the ITCZ, towards the sub-tropical high pressure belt to the North
Move east to west 
April - October 
between 5-15°
Wavelength 2000 - 25000km
last 3-4 days
travel at 18-36km/h
362
Q

Approximately __ easterly waves per week travel from Africa to _____ _____ during hurricane season

A

2

North America

363
Q

Only __ out of ___ easterly waves survive to develop into gale-force tropical storms, or full-fledged hurricanes.

A

9

100

364
Q

___ of the Atlantic tropical storms and minor hurricanes originate from easterly waves.

A

60%

365
Q

Nearly ___ of the intense (or major) hurricanes have their origins as easterly waves. _____ easterly waves become a TRS

A

85%

1 in 5

366
Q

Ice can:

A 
Add drag
Reduce thrust
Increase stall speed
Reduce lift
Add weight to the aircraft
Block pitot tubes and static vents
367
Q

Airframe icing is caused by an aircraft with airframe temperatures ___, striking a _____ _____ _____

A

<0°C

Supercooled water droplet (SCWD)

368
Q

SCWDs can exist in clouds from __ to __. For every __ below 0°C, only ___ of a droplet will freeze
instantly on impact

A

0° to -40°C
1°C
1/80

369
Q

Large SCWD’s need:

A

Great vertical depth of cloud

370
Q

Small SCWD’s need:

A

Shallow vertical depth of cloud

371
Q

Rime Ice

A

Formed when small SCWDs freeze on contact with a surface which is <0°C
Freeze almost instantly creating a mixture of tiny ice particles and trapped air.
Rough, crystalline and opaque / milky in colour
Brittle
Accumulates slowly (>20mins)

372
Q

Clear Ice

A

Formed when large SCWDs start to freeze on contact with a surface which
is <0°C
Do not freeze instantly on contact with the aircraft surface but freeze gradually as they flow back across the surface, leaving a smooth, hard, glossy, and transparent covering of ice
Heavy and difficult to see and to remove with de-icing methods,
Accumulates quickly (<20mins)

373
Q

How to avoid freezing precipitation:

A

TOGA and climb
Descend
Turn back

374
Q

Mixed ice is the blending of _____ _____ and _____ _____

A

Rime ice

Clear ice

375
Q

_____ _____ is the most common form of icing

A

Rime Ice

376
Q

Hoar frost

A

When a surface <0°C comes into contact with moist air, the water vapour turns directly into ice by sublimation

377
Q

Hoar frost occurs when:

A

When an aircraft has been parked overnight in temperatures <0°C.
When an aircraft flies from temperatures <0°C, into warm moist air, such as in descent, or climbing through a temperature inversion layer, or flying through a front

378
Q

Hoar frost can reduce lift by _____

A

10-15%

379
Q

Packed snow can be mixed with _____ _____ and can contribute to the accumulation of
_____ _____ _____.

A

Liquid water

Hazardous frozen deposits

380
Q

At faster speeds _____ SCWDs collide with the airframe,

A

More

381
Q

Kinetic heating

A

Airflow causes a rise in the temperature of the airframe due to compression and friction (Rise = (TAS / 100)2)

382
Q

Total Air Temperature (TAT) indication includes the temperature rise due to _____ _____ and is therefore used to indicate the possibility of _____.

A

Kinetic heating

Icing

383
Q

The bigger the stagnation point -

A

The less moisture hits the wing, less ice.

384
Q

Carburettor icing is caused by

A

sudden temperature drop due to fuel

vaporisation and the reduction in pressure at the carburettor Venturi

385
Q

Carburettor icing can occur in _____ _____ and at tempratures up to ___.

A

Clear air

25°C

386
Q

When information on the dew point is not available…

A

You should always assume a high relative humidity.

387
Q

Visibility definitions:

A

“The greatest distance at which a black object of suitable dimensions, situated near the ground, can be seen and recognized when observed against a bright background”

or

“The greatest distance at which lights in the vicinity of 1000 candelas can be seen and identified against an unlit background.”

388
Q

Ground visibility

A

‘The greatest known distance at which objects can be seen by an observer under conditions of normal daylight observation’

389
Q

Prevailing visibility

A

‘The greatest visibility value, observed in accordance with the definition of “visibility”, which is reached within at least 1⁄2 the horizon circle or within at least 1⁄2 of the surface of the aerodrome. These areas could comprise contiguous or non-contiguous sectors.’

390
Q

Prevailing visibility should be measured ___ above the runway and updated every __ seconds.

A

2.5m

60

391
Q

The averaging periods should be:

A

1 min for local routine reports

10 mins for METAR and SPECI

392
Q

Visibility should be reported in steps of:

A

50m when <800m
100m when 800m - 5km
1km when 5 - 10km
given as 10km or 9999 when >10km

393
Q

If visibility is observed from more than 1 location, the _____ _____ is reported first

A

Touchdown zone

394
Q

In METAR + SPECI, visibility should be reported as prevailing visibility when …..

A

Vis is not the same in different directions
lowest vis is diffrent from prevailing vis and
<1500m or
<50% of the prevailing vis and <5000m

395
Q

Runway visual range (RVR)

A

“The range over which the pilot of an aircraft on the centre line of a
runway can see the runway surface markings or the lights
delineating the runway or identifying its centre line”

396
Q

RVR is determined by…

A

Transmissiometer
Forward-scatter meter
Human observer, by counting no. of visible lights

397
Q

RVR is reported in reported in m when vis or RVR is _____

A

<1500m

398
Q

Assessed at a height of…

A

2.5m

5m if human observer

399
Q

Assessed _____ from runway center line

A

<120m

400
Q

Observations of touchdown zone should be…

A

300m along runway threshold

401
Q

Midpoint -

A

1000 - 1500m along runway threshold

402
Q

Visual range shall be reported in steps of:

A

25m when <400m
50m when 400 - 800m
100m when >800m

403
Q

R23/p1500 means

A

RWY 23

Greater than max. valus (1500m)

404
Q

R23/0400N means

A

RWY 23

Fluctuating over last 10 mins, avg 400m

405
Q

R23/1200U means

A

RWY 23

1200m with an upwards tendency

406
Q

R23/0750D means

A

RWY23

750m with a downwards tendency

407
Q

ILS

A

Instrument landing system

408
Q

MLS

A

Microwave landing system

409
Q

PAR

A

Precision approach radar

410
Q

GLS

A

Global Navigation landing system

411
Q

Aerodrome operating minima are expressed in

A

Terms of visibility and/or RVR and Decision Altitude/height (DA/DH).

412
Q

Slant visual Range (SVR)

A

‘The visual range of a specified object or light along a line of sight which differs significantly from the horizontal; for example, the visual range of ground objects or lights as seen from an aircraft on the approach (metre, m).’

413
Q

Flight visibility

A

The average forward horizontal distance, from the cockpit of an aircraft in flight, at which prominent unlighted objects may be seen and identified by day and prominent lighted objects may be
seen and identified by night.

414
Q

Mist (BR) and Fog (FG) are known as

A

Hydrometeors

415
Q

Mist limits of visibility and relative humidity

A

lower limit: 1000m
upper limit: 5000m
RH: >90%

416
Q

Fog limits of visibility and relative humidity

A

Lower limit: 0m
upper limit: 1000m
RH: 100%

417
Q

Radiation fog:

A

When ground surface cools through radiation, usually at night, cooling air above ground to the saturation temperature.
More common in Autumn/winter
Requites: clear skies, long nights, light winds

418
Q

Radiation fog is densest __________ due to __________ and goes up to heights of _____

A

1 hour after sunrise
increase in thermal turbulence
1500ft

419
Q

Radiation fog is dispersed by

A

drier air
Increase in wind speeds (>8kts)
Surface heating

420
Q

Valley fog is caused by

A

Cool air flowing down the hill (katabatic effect)

421
Q

Upslope fog is caused by

A

Air flowing upwards over rising terrain and

adiabatically cooled to its saturation temperature.

422
Q

Hill fog is

A

Low cloud covering high terrain

423
Q

Advection fog is caused by

A

Relatively warm, moist air moves (advects)
over a cooler surface, and the temperature of the air is cooled to saturation by contact with the cold surface. Requires wind of at least 15kts
can be up to 1000ft thick

424
Q

Evaporation fog is caused by

A

cold, stable air moving over a much warmer body of water.

Can be upto 500ft

425
Q

Frontal fog forms:

A

In frontal zones when rain falls from warm air into cold, stable air
Up to 200NM and be increase by orographic lifting

426
Q

Freezing fog FZFG

A

Occurs at temp <0ºC

Supercoold fog droplets freeze on impact with ground or other objects

427
Q

All fog below 0ºC is reported as

A

Freezing fog

428
Q

Ice fog forms when:

A

Water vapour, is introduced into the atmosphere and condenses, forming droplets that freeze rapidly into ice
particles.

429
Q

Ice fog is

A

Suspension of numerous minute ice particles in the air, reducing the visibility at the Earth’s surface
Observed at high latitudes, usually in clear, calm weather when the temperature is

430
Q

Shallow fog/mist is

A

MIFG/MIBR
2m high on land
10m high at sea

431
Q

Patches is:

A

BCFG
only with fog
Randomly covering aerodrome where horizontal vis is >1000m, but observer can see parts where there is less.

432
Q

Partial is:

A

PRFG

only part of aerodrome is covered by fog

433
Q

Precipitation can be considered a

A

Hydrometeor

434
Q

Low Drifing snow (DRSN)

A

Snow picked up by wind, <2m

435
Q

Blowing snow BLSN

A

Snow picked up by wind, >2m

436
Q

Lithometeors

A

A suspension in the air of extremely small (microscopic), dry particles invisible to the naked eye and sufficiently numerous to give the air an opalescent appearance

437
Q

Haze (HZ)

A

Blue light is scattered more than red light such that dark objects are seen as if viewed through a veil of pale blue.

438
Q

HZ and other lithometeors (VA, FU, SA, DU), are reported only when the visibility is _____ (except for low drifting _____ and ______ _____ which are
always reported for operational reasons)

A

<5000m
Sand
Volcanic ash

439
Q

Dust/Sand haze (DU/SA)

A

A suspension in the air of dust or small sand particles, raised from the ground prior to the time of observation by a dust storm or sandstorm.

440
Q

Low drifting dust/Sand (DRDU/DRSA)

A

Dust or sand raised by the wind to small heights (<2m), above the ground. The visibility is not sensibly diminished at eye level (eye level is defined as 1.80m above the ground).

441
Q

Blowing dust/Sand (BLDU/BLSA)

A

Dust or sand raised by the wind to moderate heights (>2m), above the ground. The horizontal visibility at eye level is sensibly reduced (eye level is defined as 1.80 m above the ground).

442
Q

Sandstorm (SS)

A

Need a minimum of 15-20kts to form
sand particles are mostly confined to the
lowest 2m, and rarely rise more than 15m above the ground.
Due to strong winds caused or enhanced by surface heating and tend to form during the day and die out at night.

443
Q

Dust storm (DS)

A

Need a minimum of 15-20kts to form
Particles of dust are energetically lifted by a strong and turbulent wind over an extensive area.
A duststorm usually arrives suddenly in the form of an advancing wall of dust which may be kilometres long and is commonly well over 3000m in height.

444
Q

Smoke (FU)

A

The suspension in the air of small particles produced by combustion
Reduces horizontal visibility to <5000m

445
Q

Volcanic Ash (VA)

A

Atmospheric dust or particles varying considerably in size, originating from active volcanoes.

446
Q

Smog

A

A mixture of smoke and fog.

Where significant industrial pollution is present

447
Q

Horizontal pressure gradient - the steeper the gradient….

A

The faster the wind is going to be

448
Q

_____ _____ _____ is what moves air from high to low pressure

A

pressure gradient force

449
Q

In the Northern hemisphere, the Coriolis deflects to the _____, and in the Southern hemisphere it deflects to the _____

A

Right

Left

450
Q

Coriolis equation:

A

CE = 2ΩρVsinθ

Ω = speed of earth
ρ = air density
V = wind speed
θ = latitude
451
Q

Buys ballot law

A

If an observer stands with his back to the wind, the low pressure system will be on his:
Left in the northern hemisphere
Right in the southern hemisphere.

452
Q

Gradient wind is the result of what 3 forces

A

PGF
Coriolis
Centrifugal

453
Q

Around a high pressure system centrifugal force acts in the _____ direction as the pressure gradient force

A

Same

454
Q

Around a low pressure system centrifugal force acts in the _____ direction as the pressure gradient force

A

Opposite

455
Q

Global winds from 90º to 0º

A

Polar Easterlies
Upper Westerlies / Prevailing Westerlies / Variable Westerlies
Tropical Easterlies / NE(or SE) Trades

456
Q

Surface winds occur below the _____ _____

A

Friction layer

457
Q

The friction between moving air and the Earth’s surface will reduce the _____ _____and _____ near the ground and therefore, the wind direction

A

Wind speed

Coriolis

458
Q

In the day, the friction lay can reach heights of _____ due to __________

A

3,000ft

Rising thermal currents

459
Q

At night, the friction layer drops to __________

A

1000 - 1500ft

460
Q

Factors affecting the vertical extent of the friction layer:

A

Terrain – the rougher the terrain, the deeper the layer
–Wind speed – the stronger the wind, the deeper the layer
Stability – the more unstable the atmosphere, the deeper the layer

461
Q

In low pressure systems, isobars are _____ _____

A

Closer together

462
Q

Over water, the wind speed in the friction layer is ___ that of 2,000ft, at ___

A

70%

10°

463
Q

Over land (day), the wind speed in the friction layer is ___ that of 2,000ft, at ___

A

50%

30°

464
Q

Over land (night), the wind speed in the friction layer is ___ that of 2,000ft, at ___

A

25%

45°

465
Q

Most reports report the wind direction in °, except HTIS or ATC which report it in °

A

°T

°M

466
Q

Wind speeds are measued at __ - __ above the ground by a

A

8 - 10m

anemometer

467
Q

The avg. observation period is ___ for local routine + ATC, and ___ for METAR + SPECI, which are reported in steps of __°

A

2 mins
10 mins
10°

468
Q

When wind speeds are

A

<0.5m/s (1kt)

469
Q

Gale force winds:

A

34-47kts

470
Q

Storm force winds:

A

48 - 63kts

471
Q

Squall

A

A sudden increase in wind speed often with a change in direction. Lasts for some minutes and can cover a much wider area.

472
Q

Lull

A

A sudden decrease in wind speed

473
Q

Sea/Land breezes only occur where…

A

there is little or no pressure gradient

474
Q

Sea breezes are caused by

A

A temperature difference between warm land and a cooler adjacent sea

475
Q

As the day goes on, sea breezes:

A

Increase in speed
Veer in NH, back in SH by approx 20- 30°
Goes further inland/out to see

476
Q

At mid latitudes, sea breezes are

A

around 20 -30 kph

10 - 15 miles either side of coastline

477
Q

Land breezes are caused by:

A

temperature difference between cooler land and a warmer adjacent sea

478
Q

Anabatic winds:

A

Light winds that blow up a mountain side due to insolation, during the day in calm weather

479
Q

Valley winds

A

Air flowing into and through a valley due to low pressure

480
Q

Katabatic winds

A

wind that carries high density air from a higher elevation down a slope under the force of gravity, occurring at night

481
Q

Mountain winds

A

Air flowing through/leaving the valley due to high pressure

482
Q

Valleys and mountain winds are prone to the _____ effect

A

Venturi

483
Q

Mistral

A 
South France
cold, often violent + dry
\+50kts
Blows through the valley of the Rhône River to the Mediterranean. effecting Sardinia, Italy 
Accompanied by clear, sunny weather
484
Q

Bora

A

The Balkans + Italy
In winter/Spring
70-100kts
Blowing on the north Adriatic coast and north Italian
plains
It forms when a high pressure lies over Central Europe and a low pressure area over the Mediterranean
Lasts many days, clouds + heavy rain

485
Q

Mountain Waves formation:

A

Occur when an air mass blows over a mountain range,
Must have:
Stable air at ridge, slightly less stable air above and below
An increasing wind velocity with altitude and wind velocity >15kts near mountaintop level
Wind direction staying roughly the same with height and within 30° of the perpendicular to the ridge line

486
Q

Mountain waves may extend _____ _____ with an average wave length of approx. _____

A

50 - 100NM downwind

5NM

487
Q

Mountain waves can extend
_____ in the Rockies
_____ in the Andes

A

300NM

500NM

488
Q

Detection of mountain waves:

A

Lenticular clouds
Rotor/roll clouds
Cap clouds

489
Q

To avoid mountain waves:

A

Cross at an angle of 30 - 45°

490
Q

Jet Steam

A

a strong narrow current, concentrated along a quasi-
horizontal axis in the upper troposphere or in the stratosphere, characterised by strong vertical and lateral wind shears and featuring one or more velocity maxima

491
Q

Speed of jet stream must be

A

> 60kts

492
Q

Jet steam ratios

A

Depth:width:length
1:100:1000

493
Q

All year jet streams:

A

Polar Front jet steam (polar - tropical air masses)

Sub-tropical jet stream (tropical - equatorial air masses)

494
Q

The arctic jet stream is

A

winter only

495
Q

Equatorial jet stream is caused by

A

Summer heating of India and coastal regions of Africa, flows from east to west

496
Q

The Polar and Sub-tropical jets are strongest in the _____ due to….

A

Winter

greater temperature differences between the respective air masses

497
Q

The ‘Jet Core’ always occurs at the point of _____ _____ _____, and it is always in the _____ air mass, just below tropopause

A

maximum pressure gradient

Warm

498
Q

Maximum windshear and CAT is also always in…

A

warm air, on cold air side of core, level with and slightly below the core

499
Q

Jet stream are _____ away from the cold front and _____ away from the warm front

A

50 - 200NM

300 - 500NM

500
Q

Climbing up through a warm front to jet stream – wind _____

Climbing up through a cold front to jet stream – wind _____

A

Veers

Backs

501
Q

Flying above the Jet Core:

A

You are in the Stratosphere
The air above the cold sector is slightly warmer than the air above the warm sector
On this track the OAT would steadily decrease
Max. CAT will be where the isotachs are closest

502
Q

Flying at the level of the Jet Core:

A

The temperature would only change slightly
Wind speed would increase as you flew into the jet stream and you would reach max. CAT
No turbulence in the jet core
The wind would decrease on the way out as you fly into the warm air

503
Q

Flying below the Jet Core:

A

The temperature would increase slightly in the cold air and would increase quickly as you cross into the warm air
The temperature would continue to increase through the warm air
Highest wind speeds would be just after crossing the frontal layer

504
Q

Isotach

A

Line connecting points of equal wind speed

505
Q

Isotherm

A

Line connecting points of equal temperature

506
Q

Jet stream clouds -

A

Cirrus

507
Q

Isohypes

A

Line of equal windshere

508
Q

Low level jet streams:

A

Due to great temp. difference between air masses or low level inversions
500 - 5000ft
70kts

509
Q

Windshear

A

change in headwind or tailwind sustained for more than a few seconds, that results in changes to the lift of the aircraft

510
Q

Gust

A

The extreme values of wind direction and speed between which the wind has varied during the last 10mins

511
Q

Turbulence is caused by

A

a rapid irregular motion of air

512
Q

Wind shear and turbulence can be found in areas of:

A 
Rough surfaces
Relief
Inversions
Cb and TS
Unstable atmospheric layers
513
Q

Wind shear and turbulence can cause

A

Airspeed + AoA fluctuations

Structural fatigue and possible damage

514
Q

The response of aircraft to wind shear depends on:

A

Type of aircraft
Phase of flight
Scale of the wind shear relative to aircraft size
Intensity and duration of the wind shear encountered.

515
Q

Information used to avoid turbulence/windshear:

A

Weather reports and forecast
Routine or Special Pilot’s reports
Visual observation
On-board predictive wind shear system

516
Q

Buildings near the runway can…

A

cause the wind flow to divert around them, resulting in the surface wind varying along the runway.

517
Q

If hills near a runway are low…

A

Range unable to divert the low-level wind flow and so the wind blows vertically downward towards the runway

518
Q

If hills near a runway are high…

A

Range able to divert the low-level wind flow and the surface wind may be funnelled along the range

519
Q

Windshear/turbulance can be caused by:

A 
katabatic flow
fohn wind 
rotors (mountain winds)
fronts
land/sea breeze
friction layer
inversions
thunderstorms
- downdrafts, gust fronts, micro/macrobusts
wingtip vortices
520
Q

Types of turbulence:

A 
Convective 
Orographic
Mechanical 
Frontal 
Clear air (CAT)
521
Q

MOD TURB:

A 
mod changes in aircraft attitude/altitude
small variations of airspeed
accelerometer readings of 0.5 - 1g
difficulty in walking in cabin
loose objects move about
522
Q

SEV TURB:

A

Abrupt changes in attiude/altitude
large variations of airspeed
accelerometer readings of >1g
Violent in cabin

523
Q

the 4 temperature groups

A

Arctic (A)
Polar (P)
Tropical (T)
Equatorial (E)

524
Q

the 2 humidity groups

A

Maritime (m)

Continental (c)

525
Q

Maritime journey:

A

A track predominantly over the sea, will increase the

moisture of the air mass, particularly in its lower layers

526
Q

Land journey:

A

A track predominantly over the land keeps the air mass dry

527
Q

Cool journey:

A

A warm air mass moving over a cooler surface is cooled from below and becomes stable in low layers

528
Q

Warm journey:

A

A cold air mass moving over a warmer surface is warmed from below and becomes unstable in low layers

529
Q

Weather fronts

A

When a warm air mass meets a cold air mass, they will mix with each other, but only in a relatively thin layer, due to temperature and density differences

530
Q

The thin mixing layer is known as the _____ _____ and is __ - __ wide at the surface

A

Transition zone

3 - 5km

531
Q

creation of fronts

A

Frontgenesis

532
Q

destruction of fronts

A

Frontolysis

533
Q

Arctic front:

A

Only tends to occur in winter
The arctic front separates the colder arctic air to the north, from the warmer polar air to the south
Greenland to Northern Norway (70N), but drops down over Iceland

534
Q

Polar front:

A

Effects the UK all year
In the UK, the polar front usually separates warm moist air from
the tropics and cold, relatively dryer air from polar regions
Winter: Between Florida and SW UK (30-50N)
Summer: Between Newfoundland / Nova Scotia and Scotland (60N)

535
Q

Mediterranean Front:

A

Forms in winter
The low-pressure systems along the Mediterranean front can develop storms, even small Hurricanes known as ‘Medicanes’
With the sand from North Africa, the RA can fall in a red colour
The local Mediterranean winds converge towards these low-pressure systems

536
Q

Stationary Front (Quasi)

A

when a cold air mass and a warmer air mass first meet, or when a front stops moving (stalls), or moves very slowly over the surface (<4kts)
Neither air mass has enough force to move or replace the other, but the air
in each airmass can still move along the front

537
Q

Stationary Front cause (if air is dry)

A

Clear to partly cloudy, with no precipitation

538
Q

Stationary Front cause (if air is humid)

A

Clouds can form and precipitation can fall
Can cause flooding if the precipitation falls continuously over an
area for several days

539
Q

Formation stage 1 - Origin + Infancy:

A

The depression starts as a small wave or ‘buckling’ along the front.
The air to the south of the front is warm tropical air
The air to the north of the front is cold polar air

540
Q

Formation Stage 2 – Maturity

A

The pressure around it falls, leading to closer isobars
This causes stronger winds and, the wave / ‘buckle’ in the front to be much more pronounced
There will be distinct warm and cold fronts being formed as the warm air is pushed towards the north and the colder pushed towards the south

541
Q

Warm front:

A

Warm air is advancing and rising up over cold air. moves at 2/3 of the wind at 2,000ft (avg. 10 -20kts)

542
Q

Warm-frontal surface:

A

Shallow - 1:100 - 1:300

543
Q

Cold front:

A

Cold air is advancing and pushing underneath warmer air. Moves at speed of wind at 2,000ft

544
Q

Cold-frontal surface:

A

Steep - 1:50 - 1:100

545
Q

An occluded front (occlusion - stage 3), is formed when

A

a cold front catches up with a warm front because the cold front is moving faster than a warm front and convergence takes place at the fronts and the warm sector of a PFD

546
Q

In a occlusion:

A

The warm sector is lifted from the surface of the earth, becomes smaller and is reduced to a trough line known as the line of occlusion

547
Q

Warm occlusion

A

The air ahead of the occluded front is colder than the air behind
More common in winter
The cloud and precipitation will be ahead of the surface occlusion

548
Q

Cold occlusion

A

The air behind the occluded front, is colder than the air ahead
More common in summer
The cloud and precipitation will be a narrow band over the whole surface occlusion

549
Q

Stage 4 – Death

A

The frontal system dies as all the warm air has been pushed up from the surface and all that remains on the surface is cold air
The occlusion dies out as temperatures are similar on both sides of the
front known as Cyclolysis

550
Q

Each section of a front moves at _____ to itself

A

90 ̊

551
Q

A frontal system moves in the direction of the _____ _____ blowing _____ to the isobars inside the warm sector, at approx. _____ of the geostrophic wind speed (_____kts)

A

Geostrophic wind
parallel
80%
15-25kts

552
Q

The time between Polar waves is approx. _____ in Europe

A

1 - 2 days

553
Q

Each PFD generally takes _____ to pass over the UK

A

9 - 12 hours

554
Q

There is a sharp change in the direction of the isobars at the front approx. ____. The isobars always turn to orient themselves towards the area of _____
pressure

A

20°

Low

555
Q

Windshear characteristics on a cold front:

A

A vigorous cold front poses the greater risk but through a shorter period
The cold front surface can stop briefly and then jump several miles, bringing very sudden gusts and wind shear

556
Q

Windshear characteristics on a warm front:

A

The effect will be ahead of it and will be more

prolonged.

557
Q

Temporary Cold Anticyclones

A

Occur between polar front depressions and provide a respite from polar front weather.
They are of significantly higher pressure than lows either side of it.

558
Q

Secondary Lows

A

Can be found behind the cold front of the primary depression.
Can be more intense than the main depression as the flow to the west of the low center is from the pole towards the equator = highly unstable

559
Q

Secondary lows move around the main depression _____ in the northern hemisphere

A

Anticlockwise

560
Q

Freezing levels in January

A

Equator - 16,000ft
40°N/S - 10,000ft
60°N/S - 0ft

561
Q

Freezing levels in July

A 
Equator - 18,000ft
40°N - 16,000ft
40°S - 8,000ft
60°N - 8,000ft
60°S - 0ft
562
Q

Temperature difference is greater in the _____ hemisphere due to __________

A

Northern

Greater land mass

563
Q

Doldrums

A

Around the equator (5°N-5°S)
Intense surface heating causes the air to warm and rise
straight up rather than blow horizontally, resulting in little or no wind

564
Q

Horse latitudes

A

At the subtropical high pressure belts (30°N/S)
Near vertical downwards motion causes little or no wind at the surface
Clear skies but with possible poor visibility due to haze and inversions

565
Q

Roaring, Furious & Screaming

A

Due to temperature variations and a greatly reduced amount of friction over the southern oceans near Antarctica, wind speeds can reach very fast speeds
Roaring 40’s
Furious 50’s
Screaming 60’s

566
Q

Monsoons

A

Characterised by a dramatic seasonal change in the
direction of trade winds
Cause dry/wet seasons

567
Q

When crossing the ITCZ:
NE trade winds become ___ trades winds
SE trade winds become ___ trade winds

A

NW

SW

568
Q

January monsoons:

A 
Oct - Apr
NW. Africa, India &amp; Eastern Asia:
- large areas of high pressure 
- dry air to south of tropics - cool dry season
- NE monsoon

N. Australia:

  • large areas of low pressure
  • warm rainy season
  • NW monsoon
569
Q

July monsoons:

A 
Apr - Oct
NW. Africa, India &amp; Eastern Asia:
- Large areas of low pressure 
- warm rainy season 
- SW monsoon

N. Australia:
No monsoon in winter

570
Q

Polar outbreak

A

The movement of a cold air mass from its source region towards the equator bringing cold weather and strong winds.

571
Q

Pampero

A

Outbreak of cold, dry polar air blowing towards the N/NE across the pampa of Argentina and Uruguay
Sometimes RA/TS
Most common Oct - Jan

572
Q

Southerly Buster

A

Outbreak of cold, polar air behind a trough of low pressure crossing SE Australia, manifesting itself as a strong, dry southerly wind which causes rapid falls of temperatures (10°C)
Most common Oct- Feb

573
Q

Cut-off low

A

Closed upper-level cold low, which has become
completely displaced (cut-off) from the westerly situation
Can remain stationary for days
Occasionally moves westward, opposite to the prevailing flow
Unsettled weather (in summer TS)

574
Q

Cold-Air drop

A

Slow moving cold low pressure in the central
troposphere between 10,000ft and 30,000ft
Normally occur in august/winter, and their diameters are approx. 2000km
Their direction and speed of movement is difficult to forecast
Lifespan of several days

575
Q

El Nino (ENSO) - Neutral

A

Trade winds blow from east to west across the surface of the tropical Pacific Ocean
Brings warm moist air and warmer surface waters to the western Pacific and keeps the central Pacific cool
Warm sea temp. in W. Pacific cause CB, RA
Dry air then travels east before descending over the cooler eastern tropical Pacific

576
Q

El Nino

A

Every 3-4 years
Easterly trade winds weaken/reverse
Allows the Pacific to warm in central + eastern areas
N + S America suffers HVY RA, floods and extream temps.
Australia, NZ, Philippines + Indonesia have droughts

577
Q

La Nina

A 
every 2 - 7yrs 
Easterly trade winds strengthen 
Warm water pushes to far west tropical pacific
Australia, HVY RA, floods
S america experiences droughts.
578
Q

Koeppen 5 zones

A

A. Equatorial Zone / Tropical Rain Climate
B. Arid Sub-tropical Zone / Dry Climate
C. Temperate Zone / Mid-Latitude Climate
D. Snow Zone / Sub-arctic Climate / Disturbed
Temperate Climate / Boreal
E. Polar Zone / Snow Climate / Tundra Climate / Cold Desert

579
Q

A. Equatorial Zone - Tropical rain forest:

A 
0° - 10°
Lowest diurnal/annual temp. variation
Max. 30 - 35°C, Min 20 - 25°C
Highest annual rainfall on earth 
No dry season 
Always under influence of ITCZ
580
Q

A. Equatorial zone - Savannah:

A

10° - 20°
lowest diurnal/annual temp. variation
20° - 30°C
1 rainy season in summer

581
Q

B. Arid zone - Desert:

A

20° - 35°
Hot in summer, large daily/seasonal variation
Dry, no wind or cloud
High evaporation

582
Q

B Arid zone - Steppe:

A

30° - 35°
Hot in summer, large variation in temp.
Dry, no wind or cloud
Slightly higher rainfall (still very little)

583
Q

C. Temperate zone - Warm:

A

35° - 40°
18 - -3°C
Summer - Hot + Dry
Winter - Cool + Wet (Rain <700mm)

584
Q

C. Temperate zone - Cool:

A 
40° - 65°
18 -  -3°C
Little season variation 
Generally wet + windy 
Predominantly westerly winds
585
Q

D. Snow zone:

A

40° - 65°
avg. temp <0°C (can be up to 60°C in peak summer)
Cool + Dry
Mostly high pressure

586
Q

E. Polar Zone:

A

65° - 90°
<10°C
Cool + Dry
Mostly high pressure

Module 1 (5 decks)

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