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ADX/Aircraft Dispatch Course > Weather Theory > Flashcards

Weather Theory Flashcards

1
Q

What is ideal air?

A

Air that lacks moisture
Nitrogen (N2) ≈ 78%
Oxygen (O2) ≈ 21%
Other ≈ 1%

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2
Q

What is coastal air?

A

Nitrogen (N2) ≈ 74%
Oxygen (O2) ≈ 20%
Other ≈ 1%
Water Vapor ≈ 5%

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3
Q

What are the phases of a microburst?

A

Formation, impact and dissipation

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4
Q

What are the 5 types of air masses?

A
  1. Continental Arctic (cA
  2. Continental Polar (cP)
  3. Continental Tropical (cT)
  4. Maritime Polar (mP)
  5. Maritime Tropical (mT)
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5
Q

Low density altitude reflects _____ than standard (ISA) temperature

A

Lower/colder

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6
Q

Higher density altitude reflects _____ than standard (ISA) temperature

A

Higher

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7
Q

A ground-based inversion develops on _____ nights with _____ wind.

A

Clear cool nights, calm wind

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8
Q

As moisture increases, air density _____.

A

Decreases

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9
Q

As temperature increases, air density _____.

A

Decreases

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10
Q

As air pressure decreases, air density _____.

A

Decreases

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11
Q

How is servere icing defined?

A
  1. Rate of ice accumulation is such that the ice protection systems fail to remove
    2.Ice is accumulating in locations not normally prone to icing
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12
Q

What are the five types of temperature variation?

A

1.Latitude - variations as you move further from the equator
2. Seasonal - variations due to the Earth’s tilt toward or away from the sun
3. Diurnal - variations in temp from day to night
4. Topography - land near water masses have smaller variation, arid regions permit greatest variations
5. Altitude - temperature lapse rate

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13
Q

Clear air turbulence (CAT) that is associated with a jet stream is most commonly found in the vicinity of the _____ and _____ fronts.

A

Tropopause, upper fronts

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14
Q

What is the size of a jet stream?

A

Thousands of miles long, hundreds of miles wide, thousands of feet tall

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15
Q

A jet stream flows in or near the _____ in a corkscrew path with the upward motion on the _____ side and the downward motion on the _____ side.

A

Tropopause, equatorial, polar

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16
Q

Define a jet stream

A

Narrow bands of wind with a speed of 50 KTS or greater

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17
Q

How does advection fog form?

A

When moist air moves over cooler ground or water. Will dissipate/lift when winds exceed 15 KTS.

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18
Q

How does fog form?

A

When the temperature, dew point, or both increase causing the air to become saturated.

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19
Q

Define VFR

A

Ceiling > 3,000’ or none AND visibility > 5 SM

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20
Q

Define MVFR

A

M - Marginal
Ceiling = 1,000’ - 3,000’ and/or visibility = 3-5 SM

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21
Q

Define IFR

A

Ceiling < 1,000’ and/or visibility < 3 SM

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22
Q

Define LIFR

A

L - Low
Ceiling < 500’ and/or visibility < 1 SM

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23
Q

Define ceiling

A
  1. Height above Earth’s surface where the lowest cloud layer base or obscuring phenomena aloft exists that can be classified as broken (BKN) or overcast (OVC)
  2. Vertical visibility into a surface-bases total obscuration
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24
Q

How is a severe thunderstorm defined?

A

Surface winds ≥ 50 KTS and/or surface hail diameter ≥ 3/4”

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25
Q

It is recommended to pilots that they clear the top of a known or suspected severe thunderstorm by how much?

A

1,000’ for each 10 KTS of wind speed

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26
Q

_____ are hidden convective clouds

A

Embedded cumulonimbus clouds

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27
Q

What are the characteristics of a steady state thunderstorm?

A
  1. Formed from weather systems
  2. More destructive
  3. Longer in duration
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28
Q

What are the characteristics of an air mass thunderstorm?

A
  1. Formed from convection
  2. Self-destructive
  3. Shorter in duration
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29
Q

What are the two classes of thunderstorms?

A
  1. Air mass (AMS)
  2. Steady state (SSTATE)
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30
Q

Describe the dissipating stage of a thunderstorm.

A

Predominantly downdrafts, microburst activity more likely

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31
Q

Describe the mature stage of a thunderstorm.

A

Both updrafts and downdrafts, precipitation begins to fall, lightning

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32
Q

Describe the formation stage of a thunderstorm.

A

Primarily updrafts, towering cumulus clouds forming

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33
Q

What are the three life stages of a thunderstorm?

A

Developing, mature, dissipating

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34
Q

What three conditions are necessary for a thunderstorm to form?

A

water vapor, unstable air, lift

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35
Q

Frost produces a roughness on the aerodynamic surfaces which may decrease lift by _____ and increase drag by _____.

A

Lift by 30%, drag by 40%

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36
Q

Frost forms near the Earth’s surface primarily on clear night with _____ air and _____ winds.

A

Stable air and light winds

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37
Q

What mid-level clouds are associated with mountain wave activity?

A

Alto-cumulus standing lenticular

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38
Q

What high-level clouds are associated with mountain wave activity

A

Cirro-cumulus standing lenticular

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39
Q

What three conditions are necessary for mountain wave activity?

A
  1. Stable air
  2. Winds ≥ 30-40 KTS
  3. Wind blowing perpendicular to the mountain
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40
Q

Define frontogenesis

A

Development of a front

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41
Q

Define frontolysis

A

Dissipation of a front

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42
Q

What can you expect if there is a change in temperature ≥ 5℃ across a front?

A

Moderate or greater turbulence

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43
Q

Define Front

A

A boundary between two air masses

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44
Q

What are the characteristics of stable air?

A

Statiform clouds/fog, continuous precipitation, smooth air, fair to poor visibility

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45
Q

What are the characteristics of unstable air?

A

Cumuliform clouds, rain showers, turbulence likely, good visibility

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46
Q

Define air mass

A

A body of air with uniform temperature and moisture

47
Q

What are the four cloud families?

A
  1. High
  2. Middle
  3. Low
  4. Clouds with extensive vertical development
48
Q

What is the measurement of atmospheric instability?

A

Lifted Index

49
Q

What determines stability?

A

Ambient temperature lapse rate

50
Q

Precipitation may be anticipated when clouds are reported to be at least _____.

A

4,000 FT

51
Q

What is supercooled water?

A

Liquid drops below freezing ex: freezing rain & freezing drizzle

52
Q

What are microscopic particles that can become condensation surfaces called?

A

Condensation nuclei

53
Q

What are the four states of water?

A
  1. Condensation
  2. Evaporation
  3. Sublimation
    4.Deposition
54
Q

When can you anticipate fog?

A

When the temperature/dew point spread is ≤ 3℃ and decreasing with light winds

55
Q

Define dew point

A

Temperature to which air must be cooled to become saturated

56
Q

Define relative humidity

A

The actual water vapor present compared to that which could be present

57
Q

Define windshear

A

A rapid change of windspeed and/or direction over a relatively short time, distance or direction

58
Q

How do high pressure winds flow?

A

Clockwise (anti-cyclonic), outward, downward

59
Q

How do low pressure system winds flow?

A

Counter-clockwise (cyclonic), inward, upward

60
Q

What is Coriolis Force?

A

Deflection of winds due to the Earth’s rotation (to the right in northern hemisphere)

61
Q

What drives winds across isobars and contours from higher to lower pressure?

A

Pressure gradient force

62
Q

Define advection

A

The horizontal movement of air

63
Q

Define convection

A

Rising air

64
Q

High Density Altitude (DA) does what to takeoff roll and runway requirement?

A

Increases

65
Q

High Density Altitude (DA) does what to performance and climb rate?

A

Decreases

66
Q

At lower than standard temperatures, density altitude is _____ than pressure altitude

A

Less than

67
Q

Define density altitude.

A

Pressure altitude corrected for non-standard temperature

68
Q

Lower pressure results in _____ pressure altitude

A

Higher

69
Q

Define pressure altitude

A

Indicated altitude when using 29.92

70
Q

Define indicated altitude

A

Altitude above MSL indicated on altimeter when using local altimeter setting.

71
Q

Pressure drops faster in _____ air

A

Colder

72
Q

What is the normal pressure lapse rate?

A

1℃/1,000’ up to ≈ 10,000’ MSL

73
Q

What is an altimeter setting?

A

The sea level pressure value to which the scale of the altimeter is set.

74
Q

What is QNH?

A

Local altimeter setting

75
Q

_____ is the actual pressure at field elevation, written as QFE.

A

Station pressure

76
Q

Inversions can commonly be found at _____.

A

The base of the stratosphere

77
Q

What is an inversion?

A

An inverted temperature lapse rate.

78
Q

What hazards are associated with an inversion?

A

Poor visibility, icing, turbulence

79
Q

Air density _____ with increased altitude.

A

Decreases

80
Q

What is the primary characteristic of the stratosphere?

A

It’s primarily isothermal

81
Q

The average depth of the tropopause is usually no more than _____.

A

A few thousand feet

82
Q

What is the primary characteristic of the tropopause?

A

An abrupt change in the temperature lapse rate

83
Q

The tropopause is a _____ layer that separates the troposphere and stratosphere.

A

Non-continuous

84
Q

Wind speed normally decreases with altitude within the _____.

A

Stratosphere

85
Q

Wind speed normally increases with altitude within the _____.

A

Troposphere

86
Q

The average thickness of the troposphere in the mid-latitudes is _____.

A

≈ 36,000’

87
Q

The troposphere layer is thickest at the _____.

A

Equator

88
Q

All weather originates in the _____.

A

Troposphere

89
Q

What is the primary characteristic of the troposphere?

A

Its temperature lapse rate

90
Q

What is ISA (International Standard Atmosphere)?

A

Average weather parameters

15℃ or 59℉
1013.2 mb(hPa) or 29.92”

91
Q

Air _____ as altitude increases.

A

Expands

92
Q

Air expansion results in lower air ____, ____ and density

A

Pressure and temperature

93
Q

Describe vertical windshear

A

VWS = ∆Speed／∆Altitude

VWS ≥ 6KTS/1,000’ = Moderate turbulence
VWS ≥ 10KTS/1,000’ = Severe Turbulence

Usually seen on climb/descent

94
Q

Describe horizontal windshear

A

HWS = ∆Speed / Distance

HWS ≥ 18 KTS / 150 NM = Moderate turbulence
HWS ≥ 40 KTS / 150 NM = Severe turbulence

Usually seen while cruising

95
Q

When you change the composition of the air, you change the _____ of the air.

A

Density

96
Q

As altitude increases, _____, _____, and _____ decrease.

A

Pressure, temperature, and density

97
Q

True or False:

Cumulonimbus tops may overshoot into the stratosphere

A

True

98
Q

True or False:

Wind speed increases with altitude in the troposphere

A

True

99
Q

Air expands as altitude increases due to _____

A

Decreasing pressure

100
Q

As air density decreases, aircraft performance ______.

A

Decreases

101
Q

As pressure decreases, air density _____

A

Decreases

102
Q

Inversions are associated with _____ air

A

Stable

103
Q

Hazards associated with inversions

A

Poor visibility, Icing, turbulence

104
Q

What is a barometer?

A

Instrument used to measure atmospheric pressure

105
Q

As we move upward through the atmosphere, the weight of the air above us ______

A

Decreases

106
Q

Pressure decreases faster in ______ air

A

Colder air

107
Q

Surface lows typically move from the ______ to the _____

A

From the west to the east

108
Q

Low pressure systems with faster horizontal movement are referred to as _____

A
  • Leaning lows
  • Implies faster winds aloft
109
Q

High pressure systems are associated with _____ weather

A

Better

110
Q

What determines how much water vapor a parcel ofair can hold?

A

Temperature

111
Q

During winter, polar jet streams migrate _____, increase in altitude, and become _____

A

migrate south, become more intense

112
Q

Subtropical jet streams are most active during _____

A

Winter

113
Q

Most turbulence occurs on the _____ side of a jet stream, in the curves of an _____ trough

A

polar side, upper trough

114
Q
A

ADX/Aircraft Dispatch Course (8 decks)

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