Meteorology Flashcards

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1
Q

What is the chemical composition of the earth’s atmosphere?

A

78% nitrogen

21% oxygen

1% CO2, inert gases

Water vapour

Impurities

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2
Q

Describe the different atmospheric layers in terms of altitude and temperature

A
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3
Q

What are the vital characteristics of the atmopshere?

A

Mobility, capacity for expansion, capacity for compression

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4
Q

List the characteristics of the ICAO standard atmosphere

A

15°C at sea level

Lapse rate of 1.98 degrees / 1000’

29.92” mercury

No humidity

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5
Q

Describe the atmospheric mass below certain altutides

A
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6
Q

What are two sources of temperature change?

A

Diurnal and seasonal

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7
Q

Where is the atmosphere heated from?

A

from below

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8
Q

Describe air in terms of conductivity and ability to absorb radiation

A

Air is a very poor conductor yet will readily absorb radiated heat

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9
Q

What is advection?

A

The horizontal transport of an atmospheric variable (like heat) due to mass motion by the wind

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10
Q

How does temperature affect the density of air?

A

Air expands when it is cool, and compresses when it is warm

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11
Q

List and describe three different ways humidity can be quantified

A

Relative humidity - how much water vapor is in the air, compared to how much it could hold at that temperature

Absolute humidity - measure of water vapor in the air, regardless of temperature

Temperature/dewpoint spread - the number of degrees of difference between the air temperature and the dew point

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12
Q

What is the dew point?

A

the temperature (in degrees) to which air must be cooled in order to be saturated with water vapor already in the air

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13
Q

Describe the state changes of water

A
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14
Q

At what humidity do clouds form? How can a parcel of air reach this humidity?

A

100% humidity

A parcel of air can become 100% humid by adding water and decreasing temperature

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15
Q

What are the following lapse rates:

Environmental

Dry adiabatic

Saturated Adiabatic

A

Environmental: 1.98°C/1000’

Dry adiabatic: 3°C/1000’

Saturated adiabatic: 1.5°C/1000’

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16
Q

List the altitude ranges for high, medium, and low clouds

A

High: 20,000’ - 40,000’

Medium: 6500’ - 20,000’

Low: ground - 6500’

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17
Q

Categorize the following clouds into low, middle, and high clouds. Which ones have vertical development?

altocrumulus, altostratus, cirrocumulus, cirrostratus, stratus, stratocumulus, nimbostratus, cumulonimbus, cirrus, cumulus

A
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18
Q

What kind of cloud is this?

A

Cirrus

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19
Q

What kind of cloud is this?

A

Cirrostratus

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20
Q

What kind of cloud is this?

A

Cirrocumulus

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21
Q

What kind of cloud is this?

A

Altostratus

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22
Q

What kind of cloud is this?

A

Altocumulus

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23
Q

What kind of cloud is this?

A

Cumulus

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24
Q

What kind of cloud is this?

A

Cumulonimbus

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25
Q

What kind of cloud is this?

A

Lens clouds

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26
Q

What kind of cloud is this?

A

Cap cloud

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27
Q

Describe orographic lifting. Where do clouds and precipitation form?

A
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28
Q

Describe how convective lifting forms a cumulus cloud

A
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29
Q

Describe how fronts form clouds

A
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30
Q

Describe the turbulence lifting agent

A

Air blowing on uneven surfaces causes uneven heating, which allows vertical currents to occur. Air moves upward, expands, and cools

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31
Q

Describe the convergence lifting agent

A

Air piles up over a region of low pressure. Excess air is forced to rise, expand, and cool

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32
Q

Describe cloud cover in oktas

A

Clear - no clouds

Few - 2 oktas

Scattered - 3 to 4 oktas

Broken - 5 to 7 oktas

Overcast - 8 oktas

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33
Q

How much does atmospheric pressure decrease with every 1000’?

A

one inch of mercury

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34
Q

How much in error will your altimeter be if you park the plane overnight and the pressure drops .10” of mercury?

A

100”

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35
Q

Define the following:

Indicated altitude, true altitude, absolute altitude, pressure altitude, density altitude

A

Indicated altitude: what the dial says

True altitude: actual height above sea level

Absolute altitude: actual height above ground

Pressure altitude: what your altimeter would read if set to 29.92”

Density altitude: a theoretical concept

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36
Q

You are at 10 000’ and your altimeter setting is 29.62”. What is your pressure altitude?

A

10,300’

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37
Q

You are at the ocean side; atmospheric pressure is 29.92” and temperature is 10°C. What is your density altitude?

A

3600 feet

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38
Q

Describe how the Koch chart is used

A
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39
Q

What is Fennel’s law?

A

Wind in the northern hemisphere is always deflected to the right

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40
Q

What is the coriolis force?

A

The force which pulls an object to the right (clockwise) in the northern hemisphere and to the left (anticlockwise) in the southern hemisphere

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41
Q

An aircraft is flying in a straight line through space. Due to the coriolis effect, in which direction does the aircraft appear to be veering?

A

Right in the northern hemisphere or left in the southern hemisphere

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42
Q

What is surface friction?

A

Friction between the surfaceon the earth and the atmosphere that will slow the movement of air

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43
Q

What is the relationship between surface friction and air’s ability to flow into a low?

A

The greater the surface friction, the more directly air flows into a low

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44
Q

What is the relative windspeed around a high and a low?

A

Wind speed is higher around a high and lower around a low

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45
Q

What is Buy Ballot’s law?

A

Standing with your back to the wind, the low is on your left and the high is on your right

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46
Q

Explain the movement of air in high and low pressure areas in terms of convergence and divergence

A
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47
Q

Explain how the land and sea breeze cycles

A
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48
Q

Explain the difference between katabatic and anabatic winds

A
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49
Q

Explain the movement of wind as it comes in contact with a mountain range

A
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50
Q

When stable air goes over a ridge, is the flow laminant or turbulent?

A

Laminar if the ridge is smooth, turbulent if the ridge is sharp

51
Q

Describe the formation of chinook winds. What is a key characteristic of chinook winds?

A

Large differences in temperature in a relatively small area

52
Q

What is glacier wind?

A

A kind of katabatic wind that forms under extreme cooling conditions

53
Q

Describe how and where jet streams form

A
54
Q

Describe the four classifications of turbulence

A

Light - slight changes in altitude/attitude or slight bumpiness

Moderate - may feel a strain against safety belt and unsecured objects dislodged

Severe - large and abrupt changes in altitude/attitude and large variations in indicated air speed

Extreme - aircraft impossible to control

55
Q

Define wind shear

A

A sudden change of horizontal or vertical wind velocity and/or direction

56
Q

What are some causes of wind shear?

A

Frontal wind shear

Temperature inversions

Surface obstructions

Low level wind shear associated with Cb

57
Q

What is the difference between gusts and squalls?

A

Main difference is the duration of the peak speed. Squalls last longer than gusts

58
Q

What is the difference between veering and backing wind?

A

Veering wind: wind that turns clockwise with height

Backing wind: wind that turns counter clockwise with height

59
Q

Describe the effect of altitude and temperature on stability

A
60
Q

What is an inversion?

A

Normally, air temperature decreases with an increase in altitude. During an inversion, warmer air is held above cooler air

61
Q

What are the air masses affecting Canada?

A
62
Q

What does the weather inside an air mass depend on?

A

The stability of the air and the moisture content

63
Q

Explain how an the properties of an air mass may be modified as it travels from its source region

A
64
Q

What is the difference between a cold front and a warm front?

A

Cold front: cold air mass is advancing

Warm front: cold air mass is retreating

65
Q

What are three large scale Canadian fronts?

A

Continental Arctic Front, Maritime Artctic Front, Maritime Polar Front

66
Q

How does a frontal depression form?

A

The boundary between two air masses is distorted by warmer air bulging into the colder air, with the bulge moving along like a wave. The cold front usually moves across the surface faster than the warm front. The pressure near the top of the wave falls sharply and a depression forms

67
Q

What is an occlusion?

A

The front formed by a cold front overtaking a warm front and lifting the warm air above the earth’s surface. An occlusion (or frontal occlusion) forms when an air mass is trapped between two colder air masses and is forced to higher and higher levels

68
Q

What is a quasi-stationary front(QS)?

A

A front where neither air mass is advancing into the other at a speed exceeding 5 knots

69
Q

Define frontogenesis and frontolysis

A

Frontogenesis: formation of a front

Frontolysis: dissipation of a front

70
Q

Define TWOWAL

A

TROugh of Warm Air ALoft. Areas of intense lift and frontogenesis are commonly associated with TROWAL

71
Q

Describe the different frontal shapes

A
72
Q

Describe cold front weather

A

Wind veers

Temperature drops

Pressure increases

Usually active weather but then cleared out

Showery precipitation

Turbulence yet good visibility

73
Q

What are the factors affecting frontal weather?

A

Speed of the front, slope of the front, temperature diference between the air masses, moisture content and stability of the air

74
Q

Describe warm front weather

A

Wind veers with passage though not abruptly

Slow rise in temperature

Low ceilings or fog, steady precipitation

Visible weather depends on moisture content and stability of air

75
Q

What are the dangers of winter warm fronts?

A

Warmer air rising over a layer of sub-freezing air may result in the formation of freezing rain. As you approach the front, the cloud layers build quickly and the clear air between layers rapidly disappears

76
Q

Define the following types of precipitation:

DZ, FZDZ, RA, FZRA, GR, SN, SG, GS, PL, IC

A

DZ: very small water drops, appear to float

FZDZ: temps at or below freezing level, drizzle will freeze on impact with object

RA: large droplets of water

FZRA: super cooled water droplets

GR: hard outer layer of ice, white core

SN: water vapour sublimated into ice crystals then agglomerates together

SG: snow crystals with rime coating

GS: soft white ice, (hail with no hard ice)

PL: frozen raindrops

IC: tiny crystals, very low temp

77
Q

Describe the cumulus stage of thunderstorm development

A
78
Q

Describe the mature stage of thunderstorm development

A
79
Q

Describe the dissipating stage of thunderstorm development

A
80
Q

List the dangers of a thunderstorm

A

Downburst (micro and macroburst), tornados, wind shear, hail, heavy rain, turbulence, freezing rain, lighting

81
Q

How should a pilot deal with a thunderstorm?

A

Avoid it

Go around it by 20nm, to the right if possible

Do not go through or under it

Do not fly between thunderstorms

Do not land near a thunderstorm

82
Q

What should a pilot do if caught in a Cb?

A

Go straight through

Reduce airspeed

Don’t try to maintain altitude

Turn on cabin lights

Descend below freezing level

83
Q

Describe the formation of ice pellets in terms of freezing levels

A
84
Q

Describe how airfoil shape, aircraft speed, and droplet size affects the rate of catch

A
85
Q

What are three types of icing?

A

Rime, clear, mixed

86
Q

What are the four levels of icing?

A

Trace, light, moderate, severe

87
Q

What should you do if icing forms during flight?

A

Turn around or climb/descend to warm air

88
Q

What two factors can affect slant range and horizontal visibility?

A

Aircraft altitude and height of cloud base

89
Q

Under what conditions does radiation fog form?

A

Still, cold night

Valleys

Clear skies

90
Q

What causes advection fog? Where is most common?

A

Warm, moist air moves over cold surface. Most common in coastal regions

91
Q

How long can advection fog last and why?

A

Can last for days over water since water does not heat up much in the daytime

92
Q

How and where does steam fog form?

A

Forms over rivers and lakes in the morning when still, cold air moves over warm water

93
Q

When does frontal fog form?

A

When precipitation falls from warm into cold air and saturates it

94
Q

What is the visibility distance due to haze?

A

6sm or less

95
Q

Define the following:

Flight visibility

Slant range visibility

Ground visibility

RVR

A

Flight visibility: air to air

Slant range visibility: air to ground

Ground visibility: as reported by an accredited observer

RVR: runway visual range

96
Q

How often are the following prepared:

METAR, SPECI, TAF,FD

A

METAR, SPECI: 24 hours at international airports

TAF: 4 times daily at aerodromes, valid for 30 hours

FD: Twice daily (00Z, 12Z)

97
Q

At what times are GFA charts issued daily? At what time are they valid?

A

Issued at 2330, 0530, 1130, 1730 UTC

Valid half hour after being issued

98
Q

What is included in a GFA chart?

A

Clouds and weather, icing and turbulence, IFR outlook for an additional 12 hour period in the final clouds and weather chart

99
Q

What are the 7 GFA areas in Canada?

A
100
Q

What are the units of measurement in a GFA?

A

Speed: knots

Height: in 100 of feet

Horizontal distance: statute miles

Time: UTC

101
Q

What criteria is IFR outlook based on?

A
102
Q

AIRMET is a short term weather advisory intended for airborne aircraft under what conditions?

A

IMC conditions < 3 SM or 1000 AGL

Freezing precipitation

MDT icing

MDT turbulence

CB isolated not area or line

Valid upon receipt

Coded A1, B1

103
Q

Decode the following AIRMET reports:

A
104
Q

What hazardous weather phenomenon is SIGMET intended for?

A

Area or Lines CB

Hail

Severe thunderstorm

Icing

Mountain wave

Hurricanes

Sand dust storms

Volcanic ash

Low level shear wind

105
Q

Decode the following SIGMET reports:

A
106
Q

What are the following abbreviations:

A
107
Q

Describe turbulence reporting duration

A

Occasional - less than 1/3 of the time

Intermittent - 1/3 to 2/3 of the time

Continuous - more than 2/3 of the time

108
Q

Describe turbulence reporting (intensity, aircraft reaction, reaction inside aircraft)

A
109
Q

The TAF is intended for flight operations within __ of the center of runway complex

A

5nm

110
Q

Decode the section in red

A

TAF = Aerodrome Forecast

CYXE = Saskatoon

281139Z = 28th Day Issued at 1139Z

111
Q

Decode the section in red

A

2812/2912 = Date Time Group

TAF Is Valid From the 28th at 1139Z until The 29th At 1200Z

Therefore this is a 24 Hour Forecast

112
Q

Decode the section in red

A

24010G25KT = Wind Group

Wind Out Of 240 Degrees True at 10 Knots Gusting To 25 Knots

113
Q

Decode the section in red

A

Wind Shear From Surface to 1100 AGL With The Wind At The Shear Height of 270 Degrees

True at 50 Knots

Prevailing visibility 3 SM in Light Snow, First Cloud Layer Broken at 1000 Feet And Overcast at 4000 feet. (First Broken Layer Is the Ceiling = 1000 Feet)

114
Q

Decode the section in red

A

TEMPO = Temporary Change is a Transitory Change Group, the following conditions apply to a TEMPO Change: Expected to last less than 1 hour and will not recur for more than 1.2 the period

The TEMPO period above is expected to start on The 28th at 1800Z and recur until the 29th at 0100Z

During the TEMPO period the visibility will decrease to 1 ½ SM in light snow and Blowing Snow With A Broken Cloud Layer (Ceiling) 800 feet

115
Q

Decode the section in red

A

During the PROB30 (probability group) period, from the 28th at 2000Z until the 28th at 2200Z the visibility will decrease to 1/2SM in snow with a vertical visibility of 500 feet AGL

116
Q

Decode the section in red

A

Following the FM which will occur on the 29th day at 0130Z the wind will be 280 degrees True at 10Knots, visibility 5SM in –SN with a broken cloud layer at 2000 feet AGL

117
Q

Decode the section in red

A

The becoming period commences on the 29th day at 0600Z to the 29th day at 0800Z; during this time period the weather will change to: wind calm, visibility greater than 6SM, sky clear. The next forecast will be issued on the 28th day by 1800Z

118
Q

In a FD, what is the code group if the wind speed is less than 5 knots?

A

9900

119
Q

Decode the following FD report

A
120
Q

What are the various weather codes for descriptors, precipitation, obscuration, and other?

A
121
Q

Describe the condition, explanation, and parameters of sky conditions in METAR

A
122
Q

Describe the ceiling, visibility, CB, preciptiation, and wind conditions conditions that could trigger a SPECI report

A
123
Q

When are SPECI reports published?

A

When one of the following elements changes between transmission times:

Wind shift direction

Wind velocity doubles or exceeds 30 knots

Temp increases by 5°C when previous was 20°C+; or decreases to reported value of 2°C or lower

Layer aloft <1000 AGL or below highest minimum IFR altitude