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Ground School - C Middleton > 9 Aviation Weather > Flashcards

9 Aviation Weather Flashcards

1
Q

What are the 4 main layers of the atmosphere (increasing altitude)?

A

Troposphere > Stratosphere > Mesosphere > Thermosphere

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2
Q

Describe the Troposhere

A

Region between surface and Tropopause at approx 36,000ft
Temp reduces with Altitude (-1.98C/1000ft)
Approx. +15C at surface to -56C at Tropopause

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3
Q

Describe the Stratosphere

A

Region between Tropopause and Stratopause (36,000 - 160,000 ft)
Temperature inversion occurs due to presence of Ozone (O3)
Approx. -56C at Tropopause to 0C at Stratopause

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4
Q

Describe the Mesosphere

A

Region between Stratopause and Mesopause (160,000 - 280,000 ft)
Temperature reduces with height due to CO2 radiative cooling
Approx 0C at Stratopause to -90C at Mesopause

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5
Q

Describe the Thermosphere

A

The region above 280,000 ft and extends to ‘space’

Temperature increases with altitude

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6
Q

Does the height of the Tropopause vary between the equator and the poles?

A

Yes.

Poles approx. 25,000 ft
Equator approx. 55,000 ft

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7
Q

Describe the 5 points of significance of the Tropopause

A
  • Lid of the weather (rarely get clouds above this point)
  • Jetsream and high winds (max wind speed around here)
  • Clear Air Turbulence (CAT)
  • Condensation trails (con-trails) most common around here
  • Jet engines are most efficient
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8
Q

Name the 4 different pressure settings

A

QFE - Field Elevation (Airfield)
QNH - At airfield corrected for mean sea level
RPS - Regional pressure setting
SPS(SAS) - Standard Pressure Setting

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9
Q

Describe QFE pressure setting

A

Pressure setting that would read 0 ft at runway height

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10
Q

Describe QNH pressure setting

A

Pressure setting that would read airfield elevation AMSL at runway

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11
Q

Describe RPS pressure setting

A

Pressure setting provided per hour for different regions

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12
Q

Describe SPS pressure setting

A

When flying at higher altitudes this is 1013.2 hPa so all aircraft are flying off the same datum pressure

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13
Q

What are the 4 properties we are concerned with in the Air?

A

Pressure
Temperature
Humidity
Density

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14
Q

How much does pressure vary with altitude (high + low level)?

A

Near surface 1hPa per 30 ft

> 20,000 ft. 1 hPa per 50 ft

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15
Q

Name the 7 Int’l Std Atm (ISA) properties (titles only)

A 
Pressure at surface
Temp at surface
Temp lapse rate
Pressure lapse rate
Height of Tropopause
Temp at Tropopause
Air Density
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16
Q

What are the 7 Int’l Std Atm (ISA) properties (titles + values)

A 
Pressure at surface = 1013.2 hPa
Temp at surface = 15C
Temp lapse rate = -1.98C/1000 ft
Pressure lapse rate = 1 hPa/30 ft 
Height of Tropopause = 36,090 ft
Temp at Tropopause = -56.5C
Air Density = 1.225 kg/m^3
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17
Q

1 hPa is equivalent to what older unit?

A

1 mbar

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18
Q

What is the Earth’s main source of heating?

A

The Sun

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19
Q

What is the heat coming from the Sun known as?

A

INcoming SOlar radiaTION

INSOLATION

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20
Q

When the Sun’s energy reaches the Earth what happens to it? (percentages and where/what)

A

50% - absorbed by the Earth’s surface
20% - absorbed by the atmosphere
30% - reflected/lost back to space

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21
Q

Name the 3 methods of heat transfer

A

Convection, Conduction, Radiation

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22
Q

Warm air …. , cold air …. (think direction)

A

rises

sinks

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23
Q

What 5 factors will impact how much energy gets to the Earth’s surface?

A 
Atmospheric Conditions
Time of Day
Season/Tilt of the Earth
Latitude
Distance to the Sun
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24
Q

The largest variation between day/night temperatures is seen over LAND or SEA?

A

LAND

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25
Q

The sea is warmest when?

A

Autumn/Early Winter

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26
Q

The sea is coolest when?

A

Spring/Early Summer

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27
Q

Going from Solid > Liquid is known as…

A

Melting

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28
Q

Going from Liquid > Gas is known as…

A

Evaporating

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29
Q

Going from Gas > Liquid is known as…

A

Condensing

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30
Q

Going from Liquid > Solid is known as…

A

Freezing (Solidifying)

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31
Q

Going from Solid > Gas is known as…

A

Sublimation

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32
Q

Going from Gas > Solid is known as…

A

Deposition

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33
Q

What is ABSOLUTE humidity?

A

The measure how actually how much water vapour is present in the air

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34
Q

What is RELATIVE humidity?

A

The ratio between how much water vapour is actually in the air over the capacity of the water vapour that can be in the air at that temperature. Expressed as a %

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35
Q

Relative humidity is expressed as a what?

A

%

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36
Q

Absolute humidity is expressed as what?

A

kg/m^3

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37
Q

When the air cannot hold anymore water vapour, it is said to be?

A

SATURATED

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38
Q

Dry air has a relative humidity (RH) of ???

A

<100%

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39
Q

What is the Dew Point?

A

The temperature when air is saturated at that given absolute humidity when cooled at constant pressure.

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40
Q

What does 05/05 mean in a METAR?

A

Temp 5C, Dew Point 5C, Humidity 100%

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41
Q

Name the 6 types of precipitation

A 
Rain
Hail
Freezing Rain
Snow
Sleet
Drizzle
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42
Q

What is the minimum diameter for hail to be defined as such?

A

5mm

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43
Q

What are the designations for the 6 precipitation types?

A 
Rain - RN
Hail - GR/GS
Freezing Rain - FZRA
Snow - SN
Sleet - RASN
Drizzle - DZ
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44
Q

Water existing below 0C is known as ….

A

supercooled water

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45
Q

Supercooled water can exist down to what temperature?

A

-40C

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46
Q

What terms are used in the water cycle?

A 
Evaporation
Condensation
Precipitation
Accumulation
Surface Run-off
Infiltration
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47
Q

What device is used to collect met data in the atmosphere?

A

Radiosonde

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48
Q

What does a radiosonde measure in the atmosphere?

A 
Temperature
Pressure
Humidity
GPS (Lat/Lon) -> Wind Dir/Speed
Altitude
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49
Q

What does ELR stand for?

A

Environmental Lapse Rate

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50
Q

What is the ELR?

A

Environmental Lapse Rate. The actual lapse rate in the atmosphere

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51
Q

A region in the atmosphere where the temp remains constant with height is called an ….

A

Isothermal layer

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52
Q

A region where temperature increases with height is called an …..

A

Inversion

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53
Q

Another line of interest rising through the atmosphere is the …..

A

Dew Point Line

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54
Q

When the TEMPERATURE and DEW POINT are at or close to the same temperature, what might we expect to see?

A

Cloud formation

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55
Q

What is an adiabatic process?

A

No energy transferred in or out of a system

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56
Q

Describe the DRY ADIABATIC lapse rate (acronym + rate)

A

DALR

-3C/1000ft

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57
Q

Describe the SATURATED ADIABATIC lapse rate (acronym + rate)

A

SALR

-1.5C/1000ft

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58
Q

ELR <1.5C/1000ft. The system is therefore ……

A

STABLE

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59
Q

ELR >1.5C/1000ft and <3C/1000ft. The system is therefore ……

A

CONDITIONALLY UNSTABLE

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60
Q

ELR >3C/1000ft. The system is therefore ……

A

UNSTABLE

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61
Q

What are the 3 kinds of stability

A

Absolute Stability
Absolute Instability
Conditional Instability

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62
Q

Describe Absolute Stability

A

ELR < SALR and DALR

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63
Q

Describe Absolute Instability

A

ELR > SALR and DALR

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64
Q

Describe Conditional Instability

A

ELR between SALR and DALR

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65
Q

Stable atmospheric conditions occur when an air packet _____ to its original level.

A

RETURNS

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66
Q

Unstable atmospheric conditions occur when an air packet ________________ its original level.

A

CONTINUES TO MOVE AWAY FROM

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67
Q

What is the average SALR?

A

1.5C/1000ft

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68
Q

What is the average DALR?

A

3C/1000ft

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69
Q

T or F? Temp inversions usually make the atmosphere more unstable.

A

FALSE

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70
Q

Warming the air from BELOW would make the air UNSTABLE or STABLE?

A

UNSTABLE

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71
Q

What is an isothermal layer?

A

A layer where the temperature remains constant with height.

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72
Q

If the ELR is 3.5C/1000ft what would the stability be?

A

UNSTABLE

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73
Q

TRUE or FALSE? The temperature at the tropopause is colder in a warm airmass compared to a cold air mass

A

TRUE

Warm air masses reach higher altitudes and therefore are cooler at the tropopause.

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74
Q

In descending order, list the layers of the atmosphere.

A

Thermosphere
Mesosphere
Stratosphere
Troposphere

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75
Q

Around the UK, at what time of year are sea temperatures likely to be lowest?

A

SPRING

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76
Q

TRUE or FALSE? When water droplets evaporate, latent heat is released?

A

FALSE

Heat is absorbed

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77
Q

If cool air is heated from below, what happens to it’s stability?

A

It becomes more unstable

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78
Q

What is an isothermal layer?

A

A layer where temperature is constant with height

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79
Q

What is the lowest temperature that water can exist as a liquid in the Earth’s atmoshere?

A

-40C

Supercooled water

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80
Q

What are the two main things we want to known about the wind?

A

Speed (Mean and Gusts)

Direction

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81
Q

Ground windspeed can be measured up to __ meter(s) off the ground

A

10 meters

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82
Q

What piece of equipment is used to measure Wind Speed?

A

Anemometer

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83
Q

Wind speed is measured in what unit?

A

Knots

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84
Q

If the gust speed is >__ kts more than the MEAN wind speed. Then the Met should inform you.

A

> 10 kts

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85
Q

The MET office typically provide wind direction in DEGREES ____

A

TRUE

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86
Q

ATC typically provide wind direction in DEGREES ____

A

MAGNETIC

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87
Q

You name the wind direction after where the wind IS GOING/COMING FROM? (Choose one)

A

COMING FROM

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88
Q

What does 28015KT tell us?

A

Wind from 280

Mean speed 15 kts

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89
Q

What does 16005KT tell us?

A

Wind from 160

Mean speed 05 kts

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90
Q

What does 08020G30KT tell us?

A

Wind from 080
Mean speed 20 kts
Gusts 30 kts

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91
Q

What does 18010KT tell us?

A

Wind from 180

Mean speed 10 kts

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92
Q

If the wind is changing in an anti-clockwise direction, it is said to be _____

A

“BACKING”

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93
Q

If the wind is changing in an clockwise direction, it is said to be _____

A

“VEERING”

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94
Q

The drive of air from High to Low Pressure is known as the ______ _____ _____(___)

A

PRESSURE GRADIENT FORCE (PGF)

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95
Q

The CORIOLIS EFFECT appears to act at ___ deg to the ____ of direction of travel in the N. Hemisphere

A

90 deg to the RIGHT of direction of travel

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96
Q

______ Wind moves parallel to isobars

A

GEOSTRAPHIC

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97
Q

Describe the “Buys Ballot” Law

A

N. Hemisphere

Back to the wind. Low pressure to the LEFT.

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98
Q

Friction on the earth surface will cause the surface wind to ____ due to the reduced Coriolis Effect due to reduced wind speed component.

A

“BACK”

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99
Q

List some types of turbulence

A
  • Clear Air Turbulence
  • Frictional Turbulence
  • Thermal Turbulence
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100
Q

What scale relates wind speed and observed sea conditions?

A

BEAUFORT SCALE

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101
Q

List some types of winds

A
  • Sea Breeze
  • Land Breeze
  • Thermal Wind
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102
Q

Describe ANABATIC winds

A

Warm air blowing up a steep slope or mountainous.

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103
Q

Describe KATABATIC winds

A

Cooler more dense air draining down a slope.

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104
Q

The ___ ____ says it is warmer and drier on the “LEE” of high ground.

A

FOHN EFFECT

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105
Q

Coriolis acts to the ____ of direction of travel in the N. Hemisphere

A

RIGHT

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106
Q

What does 24018G30KT represent in METAR?

A

Wind from 240

18kt, gusting up to 30kt

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107
Q

What happens to the wind from the late afternoon to overnight?

A

Wind speed decreases and ‘backs’

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108
Q

What can be said about the cloud base on the ‘lee’ of high ground due to the Fohn Effect?

A

Higher cloud base

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109
Q

In the UK, with LP to the East and HP to the West, what will the ‘general’ wind direction be?

A

NORTHERLY

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110
Q

Clouds are a visible collection of water _____ and/or ___ crystals

A

Water DROPLETS and/or ICE crystals

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111
Q

Clouds typically form when _____ air rises and ______.

A

MOIST air rises and CONDENSES

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112
Q

Clouds form when there is

A
  • Adequate water vapour
  • Cloud Condensation Nuclei
  • A method for air to be cooled
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113
Q

List ‘trigger actions’ that will lift and cool air

A
  • Convection
  • Orographic Uplift
  • Convergence
  • Mass Ascent
  • Turbulence
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114
Q

Clouds will disperse due to

A
  • Heating
  • Mixing with drier air
  • Reduction in Relative Humidity (RH)
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115
Q

What is the Latin meaning of “Cirrus”?

A

Lock or tuft of hair, ringlets or fibrous

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116
Q

What is the Latin meaning of “Cumulus”?

A

Heaped or Piled

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117
Q

What is the Latin meaning of “Stratus”?

A

Flattened or spread out, formed in layers

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118
Q

What is the Latin meaning of “Alto”?

A

High or height

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119
Q

What is the Latin meaning of “Nimbus”?

A

Rain bearing

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120
Q

What is the Latin meaning of “Castellanus”?

A

Castle-like, common base with vertical development

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121
Q

What is the Latin meaning of “Lenticular”?

A

Lens shaped

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122
Q

What is the Latin meaning of “Fracto”?

A

Ragged or broken

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123
Q

What is the Latin meaning of “Mammatus”?

A

Clouds with udder or pouch like patterns

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124
Q

Layered cloud will have the prefixes of

A

Cirro
Alto
Strato

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125
Q

Layered cloud will have the suffixes of

A

Stratus

Cumulus

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126
Q

Precipitation from convective clouds is known as

A

SHOWERS

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127
Q

List the 3 HIGH level LAYERED cloud types

A

Cirrostratus
Cirrocumulus
Cirrus

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128
Q

List the 2 MEDIUM level LAYERED cloud types

A

Altostratus

Altocumulus

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129
Q

List the 3 LOW level LAYERED cloud types

A

Stratus
Stratocumulus
Nimbostratus

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130
Q

List the 3 CONVECTIVE cloud types

A

Cumulus
Towering Cumulus
Cumulonimbus

131
Q

What is the designator of CIRRUS clouds

A

CI

132
Q

What is the designator of CIRROSTRATUS clouds

A

CS

133
Q

What is the designator of CIRROCUMULUS clouds

A

CC

134
Q

What is the designator of ALTOCUMULUS clouds

A

AC

135
Q

What is the designator of ALTOSTRATUS clouds

A

AS

136
Q

What is the designator of STRATUS clouds

A

ST

137
Q

What is the designator of NIMBOSTRATUS clouds

A

NS

138
Q

What is the designator of STRATOCUMULUS clouds

A

SC

139
Q

What is the designator of CUMULUS clouds

A

CU

140
Q

What is the designator of TOWERING CUMULUS clouds

A

TCU

141
Q

What is the designator of CUMULONIMBUS clouds

A

CB

142
Q

List the 3 major cloud sub-types

A

Altocumulus Castellanus
Altocumulus Lenticularis
Mammatus

143
Q

What type of cloud is of particular danger to aircraft?

A

Cumulonimbus (CB)

Associated with Heavy precipitation, Lightning, Thunderstorms and STRONG turbulence.

144
Q

Do TAFs and METARs report the cloud base in AGL or AMSL?

A

AGL

Due to it being of interest to the specific

145
Q

Cloud bases are reported in what increments of feet?

A

100s

146
Q

The ‘amount’ of cloud is measured in _____

A

OKTAS

147
Q

List the BANDS of OKTAS (inc no. of, name and designation) and the 2 other cloud descriptors.

A 
1-2 OKTAS, Few (FEW)
3-4 OKTAS, Scattered (SCT)
5-7 OKTAS, Broken (BKN)
8 OKTAS, Overcast (OVC)
Sky clear (SKC)
Sky obscured (VV//)
148
Q

If cloud cover is denoted as FEW, what does this mean?

A

1-2 OKTAS, Few

149
Q

If cloud cover is denoted as SCT, what does this mean?

A

3-4 OKTAS, Scattered

150
Q

If cloud cover is denoted as BKN what does this mean?

A

5-7 OKTAS, Broken

151
Q

If cloud cover is denoted as OVC, what does this mean?

A

8 OKTAS, Overcast

152
Q

If cloud cover is denoted as SKC, what does this mean?

A

Sky clear

153
Q

If cloud cover is denoted as VV//, what does this mean?

A

Sky obscured

154
Q

In the UK, with LP to the East and HP to the West, what will the ‘general’ wind direction be?

A

Northerly

155
Q

TRUE or FALSE? Temperature inversions usually make the atmosphere more unstable.

A

FALSE

Temp inversions make the atmosphere more stable.

156
Q

The CORIOLIS EFFECT appears to act at ___ deg to the ____ of direction of travel in the N. Hemisphere

A

90 deg to the RIGHT of direction of travel in the N. Hemisphere

157
Q

The CORIOLIS EFFECT appears to act at ___ deg to the ____ of direction of travel in the S. Hemisphere

A

90 deg to the LEFT of direction of travel in the S. Hemisphere

158
Q

List these clouds in descending order. AC, CC, ST, SC

A

CC, AC, SC, ST

159
Q

What does BKN070 stand for in a METAR or TAF?

A

Broken cloud/ 5-7 OKTAS

at 7000 ft

160
Q

List the 6 air masses specific to the UK

A 
Tm - Tropical Maritime
Tc - Tropic Continental
Pc - Polar Continental
Pm - Polar Maritime
Am - Arctic Maritime
rPm - Returning Polar Maritime
161
Q

An area of HIGH pressure is also known as an _________

A

ANTI-CYCLONE

162
Q

An area of LOW pressure is also known as a ______

A

DEPRESSION or CYCLONE

163
Q

Isobars represent lines of _____ ________

A

EQUAL PRESSURE

164
Q

Describe the LP feature known as a TROUGH (Met)

A

Isobars extended outwards from an area of low pressure.

Has a sharper ‘V’ shaped appearance in the isobars.

165
Q

Describe a COL (Met)

A

Region of almost uniform pressure between two highs and two lows.

166
Q

Describe the HP feature known as a RIDGE (Met)

A

Isobars extended outwards from an area of high pressure.

Always a rounded shape in the isobars. NEVER a ‘V’ shape.

167
Q

Name the 3 different types of LOW pressure weather

A
  • THERMAL
  • POLAR
  • OROGRAPHIC
168
Q

Describe BUYS BALLOT’s LAW

A

N. Hemisphere

Back to the wind. Low pressure to the LEFT.

169
Q

Describe typical conditions with a Tm (Tropical Maritime) air mass in EXPOSED AREAS in the UK.

(Temp, Hum, Stab, Weather, Vis)

A 
Temp - Near sea temp
Hum - Very moist
Stab - Stable
Weather - Low cloud, drizzle, fog
Vis - Often poor with costal fog
170
Q

Describe typical conditions with a Tm (Tropical Maritime) air mass in SHELTERED AREAS in the UK.

(Temp, Hum, Stab, Weather, Vis)

A 
Temp - Warm
Hum - Moist
Stab - Stable aloft
Weather - Broken cloud, dry
Vis - Moderate
171
Q

Describe typical conditions with a Tc (Tropical Continental) air mass in SUMMER in the UK.

(Temp, Hum, Stab, Weather, Vis)

A 
Temp - Very warm or Hot
Hum - Relatively Dry
Stab - Stable becoming unstable in time
Weather - Nil, possible thundery showers in time
Vis - Moderate or poor
172
Q

Describe typical conditions with a Tc (Tropical Continental) air mass in WINTER in the UK.

(Temp, Hum, Stab, Weather, Vis)

A 
Temp - Average
Hum - Rather moist
Stab - Stable
Weather - Usually cloudy
Vis - Moderate or poor
173
Q

Describe typical conditions with a Pc (Polar Continental) air mass in WINTER over LONG SEA TRACKS in the UK.

(Temp, Hum, Stab, Weather, Vis)

A 
Temp - Cold
Hum - Moist in lowest layers
Stab - Unstable
Weather - Rain or snow showers
Vis - Good, poor in showers
174
Q

Describe typical conditions with a Pc (Polar Continental) air mass in WINTER over SHORT SEA TRACKS in the UK.

(Temp, Hum, Stab, Weather, Vis)

A 
Temp - Very cold
Hum - Very dry
Stab - Stable
Weather - Very dry
Vis - Moderate to poor
175
Q

Describe typical conditions with a Pc (Polar Continental) air mass in SUMMER over LONG SEA TRACKS in the UK.

(Temp, Hum, Stab, Weather, Vis)

A

Temp - Cool, windward coasts. Warm inland
Hum - Moist near windward coasts. Dry inland
Stab - Stable
Weather - Low cloud, drizzle, mist near windward coasts. Nil inland.
Vis - Poor near windward coasts. Moderate or good inland.

176
Q

Describe typical conditions with a Pc (Polar Continental) air mass in SUMMER over SHORT SEA TRACKS in the UK.

(Temp, Hum, Stab, Weather, Vis)

A 
Temp - Warm
Hum - Dry
Stab - Stable
Weather - Dry
Vis - Moderate or good
177
Q

Describe typical conditions with an Am (Arctic Maritime) air mass in SUMMER in the UK.

(Temp, Hum, Stab, Weather, Vis)

A 
Temp - Cool
Hum - Fairly moist
Stab - Unstable
Weather - Heavy showers or thunderstorms
Vis - Very good, poor in showers
178
Q

Describe typical conditions with an Am (Arctic Maritime) air mass in WINTER in the UK.

(Temp, Hum, Stab, Weather, Vis)

A 
Temp - Cold (colder then Pm)
Hum - Moist (not as moist as Pm)
Stab - Unstable
Weather - Heavy showers, sometimes snow, hail and thunder in N. Scot and exposed coasts
Vis - Very good, poor in showers
179
Q

Describe typical conditions with an Pm (Polar Maritime) air mass in SUMMER in the UK.

(Temp, Hum, Stab, Weather, Vis)

A 
Temp - Cool
Hum - Moist
Stab - Unstable
Weather - Scattered showers
Vis - Good, poor in showers
180
Q

Describe typical conditions with an Pm (Polar Maritime) air mass in WINTER in the UK.

(Temp, Hum, Stab, Weather, Vis)

A 
Temp - Rather cold
Hum - Moist
Stab - Unstable
Weather - Heavy showers, sometimes with hail and thunder mainly in exposed W and hilly areas.
Vis - Good, poor in showers
181
Q

Describe typical conditions with an rPm (Returning Polar Maritime) air mass in the UK ALL YEAR ROUND.

(Temp, Hum, Stab, Weather, Vis)

A

Temp - Cool (warmer than Pm)
Hum - Moist (Moister than Pm)
Stab - Stable at low levels, unstable aloft
Weather - Variable cloud, possible showers
Vis - Variable

182
Q

A Tm airmass is affecting the UK. What typical weather conditions would you expect in SW England?

A

Low cloud, mist, drizzle, fog.

183
Q

What conditions would you expect in NW Scotland in a Pm airmass in Winter?

A

Unstable. SCT/BKN CU TCU CB, SHRA, TSRA

184
Q

What hazard is usually associated with a high pressure?

A

Poor visibility (haze, mist, fog)

185
Q

What is a front? (Met)

A

Boundary between 2 air masses of differing temperatures.

186
Q

List the 4 main types of fronts

A
  • Cold
  • Warm
  • Occluded
  • Stationary
187
Q

How is a COLD front depicted?

A

Blue arrows/triangles

188
Q

How is a WARM front depicted?

A

Red semi-circles

189
Q

How is an OCCLUDED front depicted?

A

Alternating Blue arrows/triangles and Red semi-circles. Same side of front line

190
Q

How is a STATIONARY front depicted?

A

Alternating Blue arrows/triangles and Red semi-circles. Alternating sides of front line

191
Q

When the shapes representing a front are hollow this indicates a _____ front.

A

UPPER front

192
Q

A weakening front is represented by ……

A

‘X’s between the respective shapes

193
Q

A strengthening front is represented by …..

A

’ . ‘s between the respective shapes

194
Q

Frontolysis is the ______ of a front

A

WEAKENING

195
Q

Frontogenesis is the ______ of a front

A

STRENGTHENING

196
Q

What front moves faster? WARM or COLD

A

COLD

Due to the front being ‘steeper’ there is less surface friction.

197
Q

How far in front of a warm front might we expect to see some precipitation?

A

Up to 400km

198
Q

In the N. Hemisphere winds ALWAYS ____ when a front passes overhead

A

VEER

199
Q

When a WARM front passes over. What will happen to the temperature?

A

Temperature will increase

200
Q

Describe what happens to the PRESSURE as a WARM front passes over

A

In advance - Falling pressure
At the passage - Falling pressure
Following passage - Steady

201
Q

Describe what happens to the PRECIPITATION as a WARM front passes over

A

In advance - Continuous rain (or snow)
At the passage - Minimal or nil
Following passage - Dry or minimal

202
Q

Describe what happens to the VISIBILITY as a WARM front passes over

A

In advance - Good except in rain (or snow)
At the passage - Poor (often mist or fog)
Following passage - Usually moderate or poor. Mist/fog near windward coasts.

203
Q

Describe what happens to the WIND as a WARM front passes over

A

In advance - Backing and increasing
At the passage - Sudden veer
Following passage - Fairly steady

204
Q

Describe what happens to the PRESSURE as a COLD front passes over

A

In advance - Steady then falling
At the passage - Rises
Following passage - Gradual rise

205
Q

Describe what happens to the PRECIPITATION as a COLD front passes over

A

In advance - Some rain, perhaps thunder
At the passage - Heavy rain (or snow) perhaps thunder or hail.
Following passage - Heavy rain (or snow) for short period, then fine, followed by showers.

206
Q

Describe what happens to the VISIBILITY as a COLD front passes over

A

In advance - Moderate poor
At the passage - Temporary deterioration followed by rapid improvement
Following passage - Very good but poor in showers

207
Q

Describe what happens to the WIND as a COLD front passes over

A

In advance - Backing and increasing
At the passage - Sudden veer
Following passage - Backing a little, then fairly steady, then fine followed by showers.

208
Q

In an OCCLUDED front, the ___ front has caught up with the ____ front.

A

COLD front caught up with the WARM front

209
Q

What are the 2 different types of OCCLUDED fronts?

A

WARM occlusion - When air ahead of the warm front is COLDER than that of the cold front approaching from behind.

COLD occlusion - When air ahead of the warm front is WARMER than that of the cold front approaching from behind.

210
Q

A _____ occlusion occurs when air ahead of the warm front is COLDER than that of the cold front approaching from behind.

A

WARM occlusion

211
Q

A _____ occlusion occurs when air ahead of the warm front is WARMER than that of the cold front approaching from behind.

A

COLD occlusion

212
Q

What air masses are associated with a COLD occlusion?

A

Pm\Tm/rPm

213
Q

What air masses are associated with a WARM occlusion?

A

Pm\Tm/Pc

214
Q

What kind of front can be found between two air masses, neither of which is strong enough to replace the other?

A

STATIONARY front

215
Q

Name and describe the 4 level of ice severity

A

Trace - Ice is perceptible
Light - 0.5cm in 15-60min
Moderate - 0.5cm in 5-15min
Severe - 0.5cm in <5min

216
Q

Name the 4 different types of icing we can expect to see on an aircraft

A
  • Rime
  • Clear/Glaze
  • Runback
  • Hoar Frost
217
Q

When will RIME icing occur?

A

Small supercooled water droplets freeze on contact below 0degC.

White or opaque due to air trapped in ice.

218
Q

When will CLEAR/GLAZE icing occur?

A

Large water drops at temp not far below 0degC and spread while freezing.

Transparent or glass-like surface. Can form horns in opposite direction of flight.

219
Q

When will RUNBACK icing occur?

A

When the thermal anti-icing system fails to evaporate 100% of water resulting in melt water progressing backwards over surface.

Freezing occurs at or near trailing edge of surfaces.

220
Q

When will HOAR FROSTing occur?

A

Clear air when the temp of the surface is below the frost-point of the air in contact with it.

221
Q

Icing is most likely to occur between __C and ___C

A

0C and -20C

222
Q

Vapour, snow or ice in a cloud WILL/WILL NOT generally cause icing on aircraft. (Choose one)

A

Vapour, snow or ice in a cloud WILL NOT generally cause icing on aircraft.

223
Q

Clouds must contain _____ ____ for ice to form

A

LIQUID WATER

224
Q

The MOST DANGEROUS type of precipitation for an aircraft is ______ ____

A

FREZZING RAIN!!!

AVOID AT ALL COSTS.
NO aircraft is certified to fly in moderate to heavy freezing rain.

225
Q

The _____ you fly the greater the amount of icing you can expect to encounter.

A

FASTER = more icing

226
Q

List some hazards to look out for associated with icing and aircraft

A

Impact icing - Build up on intakes and filters to engine.
Fuel icing - Water in fuel precipitates out and can cause blockage.
Carburettor icing - Rapid temp drop due to fuel vaporisation and adiabatic cooling.
Turbine or Jet Engine icing - Result in power loss or flame out.
Airframe/Aerofoil icing
Helicopter icing - small amounts have bigger impact

227
Q

What conditions would you expect on the East coast in winter with a Pc airmass? (long sea track)

A

Cold with snow showers

228
Q

What is usually associated with a thermal low?

A

Thunderstorms

229
Q

What is another term for a high pressure system?

A

Anti-cyclone

230
Q

How does the wind direction change on the passage of a front?

A

Always VEERS (N. Hemispshere)

231
Q

In ascending order, which cloud layers would we encounter on a warm front?

A

ST, SC, NS, AS, CS, CI

232
Q

What type of occlusion occurs when cool Pm air behind a cold front catches up with a warm front moving in to cold Pc air?

A

Warm occlusion

233
Q

Which of these clouds is most likely to give severe airframe icing?

NS, AS, CI, ST

A

NS

Nimbostratus

234
Q

Name the 3 associated LOW systems that might be encountered and describe what we might expect to experience with their presence.

A

Thermal Low - Can produce heavy Showers and Thunderstorms

Polar Low - Possibility of Thunderstorms in unstable conditions and can produce snow.

Orographic Low - Forms on ‘lee’ward side of mountains. Produces little weather but sometimes strong winds and turbulence.

235
Q

Which type of icing is transparent or translucent with a glassy surface?

A

CLEAR/GLAZE

236
Q

How is MET Visibility defined?

A

Greatest horizontal distance at which Prominent unlit objects by day and Prominent lit objects by night can be recognised.

237
Q

Name the 2 different types of visibility that can be reported

A

Prevailing - Max distance covering >0.5 of airfield

Minimum

238
Q

Define PREVAILING VISIBILITY

A

Maximum visibility covering at least 1/2 of the airfield in contiguous or non-contiguous sectors.

239
Q

When is MIN vis reported? (Mil/Civ)

A

Mil - If it changes the colour state of the airfield

Civ - If less than 1/2 prevailing and less than 10km

240
Q

How is visibility reported?

A

4 digit code representing distance in metres

241
Q

What does RVR stand for? (Met)

A

Runway Visual Range

242
Q

RVR (Runway Visual Range) is only reported when vis is less than ____m.

A

1500m

243
Q

For RVR (Runway Visual Range) what 3 letters are used to denote the tendency of the visibility?

A

D - Down or Decreasing
U - Up or Increasing
N - No or No change

244
Q

How is the RVR broken down if represented in a METAR?

A

R[Runway]/[Vis Distance][Tendency]

Eg - R01L/0400D

245
Q

What term is used when concerned with visibility at a given angle?

A

SLANT visibility

246
Q

List some things that will obscure visibility

A

Cloud and precipitation
Spray
Smoke, sand and dust
Haze, fog and mist

Sunlight and moonlight conditions

247
Q

Best visibility occurs when the SUN is ______ you.

A

BEHIND

248
Q

Best visibility occurs when the MOON is ______ you.

A

IN FRONT of

249
Q

What is the difference between BLOWING and DRIFTING particulates?

A

Blowing - Above eye level

Drifting - Below eye level

250
Q

The visibility in clouds and precipitation will depend on ……

A

Type of cloud
Type of precipitation
Amount of precipitation

251
Q

What is the major difference between Fog, Mist and Haze?

A

Fog and Mist are associated with moisture.

Haze is associated with dry suspended particulates.

252
Q

What are the approximate visibility limits of Fog(FG), Mist(BR) and Haze(HZ)?

A

Fog (FG) - <1000m
Mist (BZ) - 1000-10,000m
Haze (HZ) - <10,000m

253
Q

List the different types of Fog

A
  • Advection
  • Hill
  • Radiation
  • Arctic Sea Smoke
254
Q

What is the difference between Fog and Mist?

A

Fog - Rel Humidity >100%

Mist - Rel Humidity >95%

255
Q

What are the atmospheric conditions for Radiation Fog

A 
High rel humidity
Clear night
Light wind
Favourable topography
Moist air
256
Q

Radiation fog is dispersed when ……

A

Winds are high

Insolation (Heating from the sun)

257
Q

What are the necessary conditions for Advection Fog?

A

Warm moist air moving over cold surface

258
Q

Advection fog is dispersed when ……

A

Warming of the surface
Change of air mass
Winds increase and turbulence generated

259
Q

What are the necessary conditions for Hill Fog?

A

Moist stable air forced to rise over high ground then cools and condenses.

260
Q

Hill fog will disperse when ….

A

The air is dried or change in wind direction/reduction in strength

261
Q

What are the necessary conditions for Arctic Sea Smoke to form?

A

Cold, dry air moving over much warmer water. With an inversion to trap the fog.

(Can be created in a jar)

262
Q

Arctic sea smoke may disperse when …..

A

The inversion trapping the moisture collapses.

Difference between the air and the surface is reduced.

263
Q

A solid black line on a synoptic chart means?

A

A trough

264
Q

A cold front has passed over your station. What type of weather would you expect after the front has cleared?

A

Showers

265
Q

What conditions would you expect on the East coast in winter with a Polar Continental (Pc) airmass (long sea tracks)?

A

Cold with snow showers

266
Q

If the ELR was 4 C per 1000ft, what would the stability be?

A

Unstable

267
Q

Thunderstorms only occur with what type of cloud?

A

CB - CumuloNimbus

268
Q

List the conditions required for Thunderstorms

  • U_____ atmosphere
  • T_____ A____
  • H___ M______ C_____
A
  • Unstable atmosphere
  • Trigger Action
  • High Moisture Content
269
Q

Does WARM or COLD air hold more moisture?

A

WARM

270
Q

List the 4 trigger actions that can cause Thunderstorms?

A
  • Convergence
  • Convection
  • Mass Ascent
  • Orographic Uplift

All trigger actions apart from Turbulence.

271
Q

List the weather patterns which may present a risk of Thunderstorms

A
  • Thermal Low (Lots of air rising quickly)
  • Troughs
  • Active Cold Fronts (A strong front lots of activity)
  • Occlusions
272
Q

Describe a THERMAL LOW system

A

An area of low atmospheric pressure near the surface resulting from heating of the lower troposphere and the subsequent lifting of isobaric surfaces and divergence of air aloft.

273
Q

Describe a POLAR LOW system

A

A small but intense cyclone that forms in cold polar air advected over warmer water.

274
Q

Describe an OROGRAPHIC LOW system

A

-

275
Q

What are the 3 stages of Thunderstorms

A

Building
Mature
Dissipating

276
Q

Describe the BUILDING stage of a Thunderstorm

A
  • Small CU begin to grow
  • Strong vertical updraughts (up to 30m/s)
  • Inflow from base and sides of cell
  • Can take 15-20 mins
  • No precipitation
277
Q

Describe the MATURING stage of a Thunderstorm

A
  • Precipitation falling at base (rain or hail)
  • Cloud tops extend above 0degC level
  • Downdraughts drag cold air down
  • Drop in temp below cloud
  • Downdraught acceleration forms gust front spreading outwards.
  • Anvil clouds form due to large amount of ice crystals.
278
Q

Describe the DISSIPATING stage of a Thunderstorm

A
  • Storm has used up supply of local moisture.
  • Cloud top begins to spread laterally.
  • Downdraught abates.
  • Cloud may persist for 2 to 3 hours.
279
Q

List the 4 types of Thunderstorms

A
  • Single Cell
  • Multicell
  • Multicell -Squall Line
  • Supercell
280
Q

Describe a SINGLE CELL Thunderstorm

A
  • One time updraught and downdraught
  • Short lived
  • May produce hail and gusty wind
  • Potentially for multiple single cells in an area
281
Q

Describe a MULTICELL Thunderstorm

A
  • Each cell acts like a single cell
  • As each cell matures it is carried downwind
  • New cells tend to form in place of the preceding cell
282
Q

Describe a MULTICELL-SQUALL LINE Thunderstorm

A
  • Line of Thunderstorms
  • Can last for many hours
  • New cells form continuously at leading edge
  • May produce large hail and strong outflow winds which move rapidly ahead of system
  • Often has a shelf cloud along leading edge
283
Q

Describe a SUPERCELL Thunderstorm

A
  • Most common in N. America, rare in W. Europe.
  • Rotating updraughts
  • Type of single cell thunderstorms
  • Can persist for many hours
  • Highly organised storms
  • Can produce hail, strong winds and tornadoes
  • Entire cloud rotates
  • Exhibit wall clouds - isolated lower clouds below the rain-free base and below main storm tower.
284
Q

Name the 3 different groups of SUPERCELL Thunderstorm

A
  • Low Precipitation
  • Classic
  • High Precipitation
285
Q

What Mnemonic do we use for the Hazards of Thunderstorms?

A

WHISTLE

286
Q

What does the Mnemonic WHISTLE represent when it comes to Hazards of Thunderstorms?

A 
W - Weather (Heavy Precip)
H - Hail
I - Icing
S - Squall Line
T - Turbulence (Rapid pressure change, Downbursts, Strong Winds)
L - Lightning
E - Electricity (static)
287
Q

List some Indicators of Thunderstorms

A
  • Cloud (Rapidly building TCU, CB, AC Castellanus, Mammatus)
  • Precipitation (Hail, Rain or Snow)
  • Radar Image/ Radio Crackle
  • Lightning
  • Static Elec
  • St Elmo’s Fire
  • Visible discharge of static electricity
288
Q

What does METAR stand for?

A

METeorological Aerodrome Report

289
Q

What does TAF stand for?

A

Terminal Airfield Report

290
Q

What are the first 4 components of a METAR? (not including ‘METAR’ at the start)

A

ICAO Aerodrome code
Day/Time
Wind
Prevailing Vis

291
Q

What are the 3-6 components of a METAR? (not including ‘METAR’ at the start)

A

Wind
Prevailing Vis
Present Weather
Cloud

292
Q

What are the 5-8 components of a METAR? (not including ‘METAR’ at the start)

A

Present Weather
Cloud
Temp/Dewpoint
Pressure [QNH]

293
Q

List all the components of a METAR in order

A 
ICAO Aerodrome code
Day/Time
Wind
Prevailing Vis
Present Weather
Cloud
Temp/Dewpoint
Pressure [QNH]
294
Q

What type of occlusion occurs when cold Pm air behind a cold front catches up with a warm front with cold rPm air ahead?

A

COLD occlusion

295
Q

At what temperature is icing most likely to occur?

A

0 to -20C

296
Q

What does SCT200 stand for in a METAR or TAF?

A

3-4 OKTAS at 20,000ft

297
Q

What does 05/05 mean in a METAR?

A

Temp 5C, Dewpoint 5C, Rel Hum 100

298
Q

What does 24018G30KT represent in a METAR?

A

Wind coming from 240, 18 kt with gusts up to 30 kt.

299
Q

If the visibility is 1200 M and the RH is 98%, what weather would be reported?

A

Mist

> 1000m so NOT fog
RH cut-off for MIST = 95%

300
Q

What does the letter ‘I’ in the mnemonic ‘WHISTLE’ stand for?

A

ICING

301
Q

Which of the following is an indicator of Thunderstorms activity?

  • Drizzle
  • Turbulence
  • AC Lenticularis
  • St Elmo’s Fire
A

St Elmo’s Fire

302
Q

How long are TH (Thunderstorms) classed as ‘present weather’ for in a METAR?

A

10 mins

303
Q

How long is a METAR trend valid for?

A

2 hours

304
Q

How often are TAFs issued at a Military Airfield?

A

Every 3 hours

305
Q

In TAFs, what does the change group BECMG indicate?

A

A gradual but permanent change in one or more elements of the forecast, during the time period shown.

306
Q

Where is the Tropopause highest?

Near Equator or Near the Poles

A

Near the Equator

307
Q

True or False?

Warm air can hold more moisture than cold air?

A

TRUE

308
Q

What type of precipitation is only associated with CBs?

Showers
Snow
Hail
Drizzle

A

HAIL

309
Q

The Coriolis effect acts to the ____ in the S. Hemisphere

A

LEFT

310
Q

What 3 weather phenomena operate under the ‘10 min rule’ for present weather?

A

THunderstorms

SQualls

Funnel Cloud

311
Q

QNH in a METAR is ALWAYS rounded ____ for safety

A

Rounded DOWN

312
Q

TEMPO represents a ____ condition.

What defines TEMPO?

A

TEMPORARY condition

  • No more than 1/2 of the associated time.
  • No more than 1 hr at a time.
313
Q

Think about the 3 Cell model.

What are the names of the 3 cells?

A

Polar

Ferrell

Hadley

314
Q

What is the name of the Great Circle on the Earth which has the highest amount of thermal heating?

A

Thermal Equator

315
Q

The winds converging around the Equator from N&S Hadley zones ay also be called the …

A

Intertropical Convergence Zone - ITCZ

316
Q

In the ITCZ what type of cloud/weather might we see more often?

A

CBs and convective weather.

317
Q

The Coriolis Effect is strongest where?

A

Near the Poles

318
Q

Name the 6 climactic region types

  • P___
  • T_________
  • M_________
  • A___/D____
  • T______
  • M_________
A
  • Polar
  • Temperate
  • Mediterranean
  • Arid/Desert
  • Tropical
  • Mountainous
319
Q

Name the 3 main parts of a tropical cyclone

A
  • Eye
  • Eye wall
  • Rain bands
320
Q

What are the conditions for GREEN colours state or better?

A

3700-5000m vis

1500ft cloud base

321
Q

Requirements for Tropical Storm Formation

A

> 26C, Light Winds, 5-15 deg from Equator

322
Q

What direction are trade winds in the N.Hemisphere?

A

NE’ly

323
Q

The QNH is always rounded _____

A

DOWN

This is done for safety as your altimeter will read lower than you actually are.

Ground School - C Middleton (12 decks)

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