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Commercial Written > Aviation Weather > Flashcards

Aviation Weather Flashcards

1
Q

When does radiation fog form ?

A

Evening or Daybreak.

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2
Q

What is true about advection fog ?

A

more extensive and persistent than radiation fog. can move more rapidly.

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3
Q

Virga is described as what ?

A

streamers of precipitation trailing beneath clouds which evaporate before reaching the ground.

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4
Q

Standard Temperature (Sea Level ?)

A

15 C

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5
Q

Standard Temperature Lapse rate ?

A

2 C per 1000 ft

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6
Q

What lifts advection fog into low stratus clouds?

A

Wind 15 knots or stronger.

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7
Q

What type of fog does adiabatic cooling produce ?

A

Upslope fog.

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8
Q

What is fog produced by frontal activity known as ?

A

Precipitation-induced fog.

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9
Q

A convective cloud with virga below it could indicate what ?

A

A microburst.

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10
Q

Describe Radiation Fog

A

a warm, moist air mass settling over a cool surface under no-wind conditions.

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11
Q

Describe Advection Fog

A

forms when moist air moves over colder ground or water.

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12
Q

Dewpoint Lapse Rate ?

A

.5 deg C

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13
Q

Adiabatic lapse rate ?

A

3 deg C

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14
Q

Rate at which temperature and dewpoint converge ?

A

2.5 deg c

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15
Q

What is Radiation fog is restricted to ?

A

land because water surfaces cool little from nighttime radiation

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16
Q

When does Advection fog form ?

A

when moist air moves over colder ground or water.

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17
Q

What is Orographic lifting ?

A

lifting is caused by mountain forces, mountain winds, etc.

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18
Q

What determines the structure or type of clouds which will form as a result of air being forced to ascend?

A

The stability of the air before lifting occurs.

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19
Q

What is a temperature inversion ?

A

when warm air exists over cooler air.

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20
Q

Which are characteristics of a cold air mass moving over a warm surface?

A

Cumuliform clouds, turbulence, and good visibility.

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21
Q

Which in-flight hazard is most commonly associated with warm fronts?

A

Precipitation-induced fog arises from drops of warm rain or drizzle evaporating as it falls through cool air.

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22
Q

Whats the most easily recognized means of being alerted to possible wind shear on approach ?

A

power and vertical velocity required to remain on the proper glidepath.

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23
Q

When can a strong wind shear can be expected

A

When the speed of the jet stream is in excess of 110 knots, strong wind shears can be expected on the lower-pressure side.

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24
Q

What minimum distance should exist between intense radar echoes before any attempt is made to fly between these thunderstorms?

A

40 NM

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25
Q

Where is a common location of clear air turbulence ?

A

an upper trough on the cold (polar) side of the jet stream.

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26
Q

What are the three stages of a thunderstorm ?

A

cumulus, mature, and dissipating

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27
Q

Describe moderate turbulence

A

Changes in altitude and/or attitude occur, but the aircraft remains in positive control at all times.

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28
Q

Describe severe turbulence

A

Large, abrupt changes in altitude and/or attitude and the aircraft may be momentarily out of control.

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29
Q

What are the 2 greatest threats in thunderstorms ?

A

Hail and Turbulence

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30
Q

When flying into a low-pressure area in the Northern Hemisphere, the wind direction and velocity will be from which direction ?

A

left and increasing.

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31
Q

The general circulation of air associated with a high-pressure area in the Northern Hemisphere is

A

Air flows outward from a high-pressure area, causing a descending column of air within the high. As the air moves outward, it is deflected to the right by the Coriolis force, resulting in a clockwise rotation.

32
Q

What should you be prepared for when landing in calm wind under clear skies within a few hours after sunrise ?

A

A temperature inversion near the ground and wind shear if the winds are 25kts or greater between 2000 and 3000 ft AGL

33
Q

What is anticyclonic circulation ?

A

In the Northern Hemisphere, the flow of air from an area of HIGH to LOW pressure is deflected to the right and produces a clockwise circulation around an area of high pressure.

34
Q

Which feature is associated with the tropopause?

A

Abrupt temperature changes.

35
Q

When flying low over hilly terrain, ridges, or mountain ranges, the greatest potential danger from turbulent air currents will usually be encountered on the

A

leeward side when flying into the wind.

36
Q

One of the most dangerous features of mountain waves is the turbulent areas in and where ?

A

below rotor clouds.

37
Q

During the winter months in the middle latitudes, the jet stream shifts toward which cardinal direction ?

A

south and its speed increases.

38
Q

When does an occluded front occur ?

A

When a cold front overtakes a warm front.

39
Q

What are the conditions most favorable to wave formation over mountainous areas ?

A

stable air at mountaintop altitude and a wind of at least 20 knots blowing across the ridge.

40
Q

How is moisture is added to a parcel of air ?

A

Evaporation or Sublimation. (i.e when liquid water or ice are changed into water vapor.)

41
Q

Ice pellets encountered during flight normally are evidence of what ?

A

Either a warm front or a cold front is about to pass.

42
Q

What does a curving jetstream indicate ?

A

Abrupt weather system changes, which lend themselves to more violent turbulence.

43
Q

In general what do more pronounced differences in weather systems indicate ?

A

greater the potential for very strong turbulence.

44
Q

Which is true with respect to a high- or low-pressure system?

A

A high-pressure area or ridge is an area of descending air.
High-pressure air descends because it is heavier than low-pressure air. Ridge refers to an elongated area of high pressure.

45
Q

What does a Trough refer to ?

A

An elongated area of low pressure.

46
Q

Why does low pressure rise ?

A

Because it weighs less than high-pressure air.

47
Q

The minimum vertical wind shear value critical for probable moderate or greater turbulence is what ?

A

Moderate or greater turbulence should be expected where vertical wind shears exceed 5 knots per 1,000 feet.

48
Q

What prevents air from flowing directly from high-pressure areas to low-pressure areas?

A

The Coriolis force

49
Q

When is Hazardous wind shear commonly encountered ?

A

in areas of temperature inversion and near thunderstorms.

50
Q

What is the minimum vertical wind shear value critical for probable moderate or greater turbulence ?

A

5 knots per 1,000 feet.

51
Q

A situation most conducive to the formation of advection fog is

A

an air mass moving inland from the coastline during the winter.

52
Q

Which type of pressure system has heavier air ?

A

High-pressure air descends because it is heavier than low-pressure air. Ridge refers to an elongated area of high pressure.

53
Q

In what ways do advection fog, radiation fog, and steam fog differ in their formation or location?

A

Radiation fog is restricted to land areas; advection fog is most common along coastal areas; steam fog forms over a water surface.

54
Q

The minimum vertical wind shear value critical for probable moderate or greater turbulence is ?

A

5 knots per 1,000 feet.

55
Q

Fog produced by frontal activity is a result of saturation due to ?

A

evaporation of precipitation.

56
Q

Which combination of weather-producing variables would likely result in cumuliform-type clouds, good visibility, and showery rain?

A

Unstable, moist air and orographic lifting.

57
Q

On a flight from west to east, what side of a high-pressure system would have the most favorable winds. ?

A

North-side, due to anticyclonic circulation. (clock-wise circulation around high-pressure)

58
Q

The wind system associated with a low-pressure area in the Northern Hemisphere is

A

a cyclone and is caused by Coriolis force.

59
Q

Which is true regarding actual air temperature and dew point temperature spread? The temperature spread

A

decreases as the relative humidity increases. (i.e As relative humidity increases to 100%, the dew point approaches the temperature and the spread approaches zero.)

60
Q

The wind system associated with a low-pressure area in the Northern Hemisphere is…

A

a cyclone and is caused by Coriolis force.

61
Q

The conditions most favorable to wave formation over mountainous areas are a layer of

A

stable air at mountaintop altitude and a wind of at least 20 knots blowing across the ridge.

62
Q

Convective circulation patterns associated with sea breezes are caused by

A

land absorbing and radiating heat faster than the water.

63
Q

Which statement is true regarding squall lines?

A

They are nonfrontal and often contain severe, steady-state thunderstorms.

64
Q

Streamlined, windswept cirrus clouds always indicate what ?

A

very strong upper winds.

65
Q

A common location of clear air turbulence is

A

in an upper trough on the polar side of a jet stream.

66
Q

Which would increase the stability of an air mass?

A

Cooling from below.

67
Q

From which measurement of the atmosphere can stability be determined?

A

The ambient lapse rate.

68
Q

What is an important characteristic of wind shear?

A

It can be present at any level and can exist in both a horizontal and vertical direction.

69
Q

During departure, under conditions of suspected low-level wind shear, a sudden decrease in headwind will cause

A

a loss in airspeed equal to the decrease in wind velocity.

70
Q

Fog produced by frontal activity is a result of saturation due to

A

evaporation of precipitation.

71
Q

Which is true regarding the development of convective circulation?

A

Cool air must sink to force the warm air upward.

72
Q

What should you be prepared for when landing in calm wind under clear skies within a few hours after sunrise ?

A

A temperature inversion near the ground.

73
Q

Why does high-pressure air descend ?

A

Because it is heavier than low-pressure air.

74
Q

The difference found by subtracting the temperature of a parcel of air theoretically lifted from the surface to 500 millibars and the existing temperature at 500 millibars is called what ?

A

The lifted index.

75
Q

What does the ambient lapse help determine ?

A

Stability of the atmosphere.

76
Q

Advection fog has drifted over a coastal airport during the day. What may tend to dissipate or lift this fog into low stratus clouds?

A

Wind 15 knots or stronger.

Commercial Written (13 decks)

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