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AVIA 203 > Meteorology > Flashcards

Meteorology Flashcards

1
Q

What is the rough Composition of the Atmosphere?

A

79% Nitrogen
21% Oxygen
1% Argon
0.05% Other Gases

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2
Q

What is the Temperature Trends in the different divisions of the Atmosphere?

A

Troposphere - Down
Stratosphere - Up
Mesosphere - Down
Thermosphere - Up

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3
Q

Where does most weather in the atmosphere occur?

A

Troposphere

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4
Q

What is the height of the Troposphere over the poles vs the equator?

A

28,000’ over the poles
54,000’ over the equator

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5
Q

What is the ICAO Standard Atmosphere in terms of Mean Sea Level Pressure, Mean Sea Level Temperature, & Lapse Rate?

A

29.92” Hg
15°C
1.98°C/1000’

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6
Q

What are the 3 Principle Properties of the Atmosphere?

A

Expansion
Compression
Mobility

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7
Q

As moisture goes from Ice to Water is heat absorbed or released?

A

Absorbed

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8
Q

What is the Definition of Dewpoint?

A

Temperature, at a given pressure, to which air must be cooled to cause saturation

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9
Q

What is the Definition of Relative Humidity?

A

Compares amount of water vapour in the air to amount if could hold if it were saturated, expressed as a percentage

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10
Q

What is denser Cold Air or Warm Air?

A

Cold Air

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11
Q

What kind of radiation is Terrestrial Radiation?

A

Infrared

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12
Q

What are the 6 Atmospheric Heating Processes?

A
  1. Conduction - Heating through contact
  2. Convection - Warm air is less dense and tends to rise
  3. Turbulent Mixing - Friction causes eddies to form as air moves over surfaces
    Advection - Horizontal movement of air masses
    Compression - Descending air increasing in pressure, in turn increasing in temp
    Release of Latent Heat - Changing state down an energy level
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13
Q

Which way does air flow around a High Pressure Centre?

A

Clockwise

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14
Q

Which way does air flow around a Low Pressure Centre?

A

Counter-Clockwise

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15
Q

Does air aloft converge or diverge around a High Pressure System?

A

Converge

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16
Q

What are the 6 Adiabatic Atmospheric Cooling Processes?

A
  1. Expansion Cooling - Rising air expands, cools according to lapse rate
  2. Orographic & Upslope Lift - Result of air flowing over features that cause air to rise
  3. Frontal Lift - Occurs when warm air forced up along a frontal surface
  4. Mechanical Turbulence - Same mechanism as warming
  5. Convection - Rising air cools according to lapse rate
  6. Convergence - Air at centre of low rises, causes cooling
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17
Q

What is the Dry Adiabatic Lapse Rate and the Saturated Adiabatic Lapse Rate?

A

DALR: 3°/1000’ (< 100% relative humidity)
SALR: 1.5°/1000’ (100% relative humidity)

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18
Q

What displaces what - cold air or warm air?

A

Cold Air displaces Warm Air

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19
Q

What are 2 other Cooling Processes?

A
  1. Radiation Cooling - Surface temps below air temps, surface emits heat into colder upper atmosphere
  2. Non-Expansional Cooling - Advection - air moving older colder surface. Evaporation - heat absorbed
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20
Q

Describe Stable, Unstable and Neutral Air?

A

Stable - Will return to original state
Unstable - Will move further way from original state
Neutral - Will remain at disturbed state

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21
Q

What determines Atmospheric Stability?

A

Temperature Difference between rising air parcel and surrounding air

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22
Q

What is an Isothermal Layer?

A

Temperature doesn’t change with change in altitude, very stable

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23
Q

What is an Inversion?

A

Temperature increases with height, extremely stable

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24
Q

What kind kind of Cloud is formed in Stable vs Unstable Air?

A

Layered (Stratiform) - Stable
Heaped (Cumuliform) - Unstable

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25
Q

How do you calculate Cloud Base?

A

(Spread/2.5)*1000’ = Height AGL

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26
Q

How do you calculate Freezing Level?

A

(Dewpoint/2.5)*1000’ = Height Above Cloud Base

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27
Q

What height separates the different Cloud Classifications?

A

High - >20,000’ ASL
Middle - 6,500 - 20,000’ ASL
Low - < 6,500’ ASL

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28
Q

What are the prefixes associated with the different heights of clouds?

A

Cirro - High
Alto - Middle
Strato - Low

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29
Q

What are thunderstorm clouds called?

A

Cumulonimbus (CB)

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30
Q

When does a thunderstorm reach its mature stage?

A

When precipitation hits the ground

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31
Q

What is Fog?

A

Stratus cloud at ground level

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32
Q

What are 3 Requirements for Fog to form?

A
  1. High Relative Humidity
  2. Abundance of Condensation Nuclei
  3. Mixing Action
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33
Q

What are the 5 different types of Fog?

A
  1. Radiation Fog - Cool, clear nights with high relative humidity - found in low lying areas
  2. Advection Fog - Coastal areas when warm, moist air moves over a cold surface, doesn’t burn off needs change in wind direction
  3. Steam Fog - When cold air moves over warm water surfaces - found over rivers and small lakes, evaporation saturates air
  4. Frontal Fog - During passage of warm front
  5. Ice Fog - Very cold days, very small ice crystals, associated with hoar frost
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34
Q

What is the difference between Fog and Mist?

A

Visibility
Fog < 1/2 SM
Mist > 1/2 SM

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35
Q

What is Pressure?

A

Weight of an imaginary column of air

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36
Q

What are 2 forms of Pressure Measurement?

A
  1. Mercury Barometer
  2. Aneroid Barometer
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37
Q

What is Station Pressure?

A

Weight of column of air lying above an airport

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38
Q

What is Mean Sea Level Pressure?

A

Station Pressure + Weight of column of air between ground and sea level - using average temp from last 12 hrs

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39
Q

What is Altimeter Setting?

A

Station Pressure + Weight of column of air between ground and sea level - calculated using ICAO standard atmosphere

40
Q

What is a Low Pressure System called?

A

Cyclone

41
Q

What is a High Pressure System called?

A

Anti-Cyclone

42
Q

What is an Isobar?

A

Lines joining places of equal pressure

43
Q

What is Buy-Ballot’s Law?

A

If you stand with your back to the wind in the Northern Hemisphere, the low pressure will be on your left

44
Q

What determines the intensity of a Pressure Gradient Force (PGF)?

A

Spacing between isobars

45
Q

What is the Coriolis Effect?

A

The atmosphere doesn’t rotate at the same speed as the surface so air will rotate

46
Q

What is the Friction Effect?

A

Topographical features effect movement of air, reducing wind speeds at low level

47
Q

What is the difference between Veer and Back?

A

Veer - Clockwise change in wind direction (during climbs - veers and increases - less surface friction)
Back - Counter-clockwise change in wind direction (descents - backs and decreases)

48
Q

What is the difference between Land and Sea Breeze?

A

Sea Breeze - During day - land warms up more quickly than water (sea -> land)
Land Breeze - At night - land cools more quickly than water (land -> sea)

49
Q

What is the difference between Anabatic and Katabatic Wind?

A

Anabatic - Occurs during day, sun warms side of mountain, air less dense rises up mountain
Katabatic - Occurs at night, air cools, air becomes more dense and falls down mountain

50
Q

What is Wind Shear?

A

Sudden change in wind speed/direction

51
Q

What is an Air Mass?

A

Large section of troposphere with uniform properties of temperature & moisture in the horizontal

52
Q

What Moisture Content can an Air Mass have and what Temperature Content can an Air Mass have?

A

Moisture: Maritime or Continental
Temperature: Arctic, Polar, Tropical

53
Q

When a Cold Front overtakes a Warm Front what determines the weather?

A

Moisture content & stability of warm air mass

54
Q

What are common characteristics of cold front passage?

A

Decrease in temp, wind shift (veer & increase), pressure increases followed by clearing skies

55
Q

When a Warm Front is overtakes a Cold Front what determines the weather?

A

Moisture content & stability of warm air mass

56
Q

What is an Upper Front?

A

Narrow transition zone between two air masses where no temp difference at surface - front doesn’t come all the way down

57
Q

What are thunderstorms called when formed by a steep cold front?

A

Frontal Thunderstorms - Squall Line

58
Q

What are thunderstorms called when formed by daytime heating/unstable air mass?

A

Air Mass Thunderstorms - not as organized

59
Q

What is the difference between the Cumulus and Dissipating stage of a Thunderstorm?

A

Cumulus - Mainly updrafts
Dissipating - Mainly downdrafts

60
Q

What are the 2 requirements for Icing?

A
  1. Visible moisture
  2. Below freezing temps
61
Q

What is Clear, Rime and Mixed Icing?

A

Clear - Slow Freezing, Smooth
Rime - Rapid Freezing, Bumpy
Mixed - Combination

62
Q

How does icing effect lift and drag?

A

Decreases Lift by 30%
Increases Drag by 40%

63
Q

What are the different types of Icing in Layer, Vertical, and Towering Cumulus Cloud?

A

Layer - Freezing Level - -5°C (Rime)
Vertical - Freezing Level - -15°C (Clear)
Towering Cumulus - Up to -25°C

64
Q

What is Frost?

A

Sublimation of water vapour directly onto A/C

65
Q

What are the 2 requirements for for Frost?

A
  1. Cold, clear night
  2. Rapid descent in below freezing temp (hoar frost)
66
Q

What is Turbulence?

A

Unpredictable & irregular motion of air

67
Q

How is the wind reported in a METAR?

A

2 min mean wind direction and speed
Gusts need to be 5 kts or more than steady speed
Variations - preceding 10 mins varies between 60°-180°, and speed greater than 3kts

68
Q

What does MI, BC, SG, GR, GS, FU, +FC mean in a METAR?

A

Shallow
Patches
Snow Grains
Hail
Snow Pellets
Smoke
Tornado

69
Q

When in wind shear reported in a METAR?

A

Up to 1600’ when pilot reported

70
Q

What altitude does a GFA go up to?

A

24,000’

71
Q

Does each new set of GFA charts replace the preceding ones?

A

Yes

72
Q

What is altitude measured in in a GFA?

A

Hundreds of Feet ASL

73
Q

What are the requirements to be considered IFR, MVFR, and VFR?

A

IFR: < 1000’ AGL or < 3 SM
MVFR: 1000’ - 3000’ AGL or 3 - 5 SM
VFR: > 3000’ AGL and > 5 SM

74
Q

What interval are isobars shown in?

A

4 mb intervals

75
Q

When is motion shown for synoptic features?

A

When it moving greater than 5 kts

76
Q

When are scalloped borders used to enclose cloud cover?

A

When it is BKN or OVC

77
Q

What does a dashed green line in an area, and a solid green line in an area represent?

A

Dashed Green Line - Showery Precipitation
Solid Green Line - Continuous Precipitation

78
Q

What are the abbreviations used for Convective Cloud and Showers?

A

ISOL - < 25%
SCT - 25 - 50%
NMRS - > 50%

79
Q

What are the abbreviations used for Non-Convective Cloud and Showers?

A

LCL - < 25%
PTCHY - 25 - 50%
XTNSV - > 50%

80
Q

When is speed and direction of surface winds shown on a GFA?

A

When there is a sustained speed equal to or greater than 20 kts

81
Q

What interval are freezing level lines indicated at on a GFA?

A

2,500’ Intervals

82
Q

What area are TAFs applicable in?

A

5 NM surrounding aerodrome

83
Q

What is the maximum number of significant weather groups that can be reported at one time in a TAF?

A

3

84
Q

What does FM represent in a TAF?

A

Permanent change group (rapid), all conditions before are superseded

85
Q

What does BECMG represent in a TAF?

A

Permanent change group (gradual), occurs in 2 or less weather elements, if deteriorating apply at beginning, if improving apply at end

86
Q

What does TEMPO represent in a TAF?

A

Transitory change group, temporary fluctuation during specific period

87
Q

When is the 3000’ level of an FD eliminated?

A

When ground elevation >1,500’

88
Q

What is the process for reporting FDs when the wind speed is from 100-199 kts?

A

Add 50 to direction
Subtract 100 from speed

89
Q

What is the process for reporting FDs when the wind speed is above 199 kts?

A

Will be reported as 99

90
Q

What is a PIREP?

A

Observations of actual conditions taken by pilots during flight

91
Q

What is a SIGMET?

A

Highlights significant weather - broadcast on 126.7 in affected areas

92
Q

What is an AIRMET?

A

Highlights conditions that have changed from a GFA, but don’t require a SIGMET

93
Q

When is a Surface Analysis Map issued?

A

4 times a day at 6 hour intervals

94
Q

How far up does a Surface Analysis Map represent the weather?

A

3000’ AGL

95
Q

When is an Upper Air Analysis issued?

A

Twice a day 0000z and 1200z

96
Q

What altitude does the 750 mb chart of an Upper Air Analysis represent?

A

10,000’

97
Q

What is the difference between Satellite and Radar?

A

Satellite shows cloud cover
Radar shows precipitation or cloud tops

AVIA 203 (3 decks)

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