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PPL > Meteorology > Flashcards

Meteorology Flashcards

1
Q

What does a blue line with blue triangles associate with?

A

A cold front

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2
Q

Which moves faster and is stronger, warm or cold weather fronts?

A

Cold weather fronts move more quickly and are stronger

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3
Q

What way does air travel around a cold front?

A

Clockwise

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4
Q

What is humidity?

A

How close the air is to saturation

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5
Q

What is a squall line?

A

A line of thunderstorms produced ahead of a cold front, can be up to 100nm long and 20nm wide.

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6
Q

How far ahead of a main cell can thunderstorms and turbulence develop?

A

20nm

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7
Q

To be classified as a squall, what needs to happen?

A

Winds speed must change by at least 16kts to reach 22kts or more and maintain that speed for more than 1 minute.

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8
Q

What is described as low cloud?

A

Base of cloud between sea level and 8000ft

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9
Q

What clouds are classified as low clouds?

A

Cu-Cumulus, Sc-Stratocumulus, St-Status and Cb-Cumulonimbus

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10
Q

What is Cu-Cumulus associated with?

A

An unstable atmosphere

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11
Q

What are Sc-Stratocumulus and St-Status associated with?

A

A stable atmosphere

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12
Q

What is Cb-Cumulonimbus associated with?

A

Thunderstorms

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13
Q

What are the conditions that facilitate the formation of fog?

A

High humidity resulting in a higher dew point temperature. Clear night skies allow greater cooling of the surface and thus atmosphere by conduction. Light winds (5-7kts) which can cause thickening of fog.

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14
Q

What are the two types of fog?

A

Radiation and Advection

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15
Q

What needs to occur for radiation fog and what causes it to dissipate?

A

Clear skies, light winds, and cool air. An increase in wind speeds resulting in the fog mixing with drier air and an increase in solar radiation resulting in the temperature in the air increasing.

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16
Q

What is Advection fog and how does it form?

A

Advection fog forms when warm humid air moves over cold ground and is cooled to its dew point temperature by conduction with the cold surface.

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17
Q

What is slant visibility in fog?

A

Lower visibility caused by looking through more fog. When straight above, you may only be looking through 600ft but on an angle, you are looking through a greater amount of fog causing lower visibility.

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18
Q

What is Frost?

A

Frost is simply frozen dew which forms on aircraft surfaces when left out overnight. It can disrupt the airflow over the wing causing a loss of lift and increase in drag, severely reducing the climb performance.

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19
Q

What is Hoar Frost?

A

When cruising at high altitude for several hours, every part of the airframe cools to the same temperature as the outside, known as ‘cold soaking’. If the aircraft then descends through warm humid air, water vapor can skip the liquid state and turn directly to ice on its cold surfaces.

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20
Q

What are inversions and how are they caused?

A

Inversions are stable air masses where the cooler air is near the earth’s surface and the warmer air is on top of it. An inversion layer is usually a sign of an extremely stable atmosphere.

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21
Q

What are Anabatic winds?

A

Anabatic winds blow up a sloping terrain during the afternoon to replace rising warm air which has been heated by contact with the hill slopes.

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22
Q

What are Katabatic winds?

A

During the night, the air becomes chilled by conduction over the plateau, eventually dropping to a point where it becomes heavier than that of the lower air.

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23
Q

What are Sea and land breezes?

A

They occur due to the difference in heating/cooling rates of land compared to water.

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24
Q

What are the two types of turbulence?

A

Convection turbulence and Mechanical

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25
Q

What is convection turbulence?

A

As air is heated, it becomes less dense and begins to rise, creating thermals.

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26
Q

What is mechanical turbulence?

A

At low level, turbulent eddies are formed when wind flow encounters obstacles.

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27
Q

What are Dust Devils?

A

Localized columns of low pressure, rotating rapidly, typically about 30m in diameter, generating speeds of 30-50kts.

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28
Q

What are Mountain Waves?

A

When strong winds blow at right angles to a mountain range, wave action can be set up after the air has passed over the mountain range.

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29
Q

What are Lenticular Clouds?

A

They form on the crests of the downward waves, have smoothly rounded tops and flat bottoms, and remain stationary.

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30
Q

What are the three stages of a thunderstorm?

A

Growing, Mature, and Dissipation

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31
Q

What happens in the growing stage of a Thunderstorm?

A

The rising air will reach saturation and cumuliform cloud will develop, consisting primarily of liquid water droplets.

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32
Q

What happens in the Mature stage of a Thunderstorm?

A

The air within the Cb-Cumulonimbus cloud becomes colder than the surrounding air and sinks, creating downdrafts.

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33
Q

What happens in the dissipation stage of a thunderstorm?

A

The air movements within the thunderstorm consist primarily of downdrafts, with rain, snow, and ice still present.

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34
Q

What are the hazards of a thunderstorm?

A

Pilots should avoid taking off or landing with approaching thunderstorms and do not attempt to fly under a thunderstorm. Due to the downdrafts they cause.

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35
Q

What is the greatest hazard from thunderstorms for pilots and what stage does this occur?

A

Severe Turbulence, and downdrafts greatest in the Mature stage.

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36
Q

What is an OCTA and what is it used to describe?

A

An OCTA is 1/8 of the sky, used to describe how much cloud cover is present.

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37
Q

What is a METAR?

A

Meteorological Aerodrome Report (METAR) is a routine report made by an approved observer at fixed times at a particular location.

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38
Q

What is a SPECI?

A

A special report issued when conditions at an aerodrome fluctuate significantly or are below a certain criteria.

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39
Q

What is CAVOK?

A

Visibility of greater than 10km and no cloud below 5000FT or below

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40
Q

What is ATIS?

A

Automatic terminal information service broadcast at specified aerodromes containing both meteorological and terminal information.

41
Q

What is an AWIS?

A

Automatic Weather Information Service (AWIS) broadcast at specified aerodromes containing only meteorological information.

42
Q

What is a TAF?

A

Terminal Area Forecast (TAF) is a statement of meteorological conditions expected for a specified period in the airspace within a 5NM radius of an aerodrome.

43
Q

What is an INTER?

A

Within a specified time period, there may be periods of intermittent changes in the weather for up to 30 minutes at a time.

44
Q

What is a TEMPO?

A

Within a specified time period, there may be periods of temporary changes in the weather for up to 60 minutes at a time.

45
Q

What is a PROB%, FM and BCMG?

A

PROB% indicates a chance of a weather occurrence, FM indicates a rapid change in weather conditions, and BCMG indicates a gradual change.

46
Q

What is a TAF3?

A

TAF 3 service is similar to TAF but issued every 3 hours and kept under continuous weather watch.

47
Q

What is a GAF?

A

A graphical area forecast (GAF) does not describe weather conditions for a specific location but refers to a defined area.

48
Q

What is a GPWT forecast?

A

Grid Point Wind and Temperature (GPWT) forecast displays wind and temperature information as a table of numbers overlaid on a map.

49
Q

What is a SIGMET?

A

SIGMET is a concise description of meteorological phenomena that may have a significant impact on flight safety.

50
Q

What is a nominated alternate aerodrome?

A

It is suitable as a destination for the flight in question and not an aerodrome for which a flight would be required to make provisions for an alternate.

51
Q

When do you require an alternate aerodrome?

A

When the weather is below VFR alternate minima, including cloud, visibility, crosswind, and thunderstorms.

52
Q

What is the Atmosphere composed of?

A

The earth is surrounded by a mixture of gasses held to the planet by the force of gravity, known as air or the atmosphere.

53
Q

What is the maximum approved crosswind component?

A

The maximum approved crosswind component can be found in the aircraft flight manual (AFM).

54
Q

What provisions must be made when thunderstorms are forecast at the destination?

A

Provisions to proceed to a suitable alternate aerodrome must be made.

55
Q

What is the atmosphere?

A

The atmosphere is a mixture of gasses held to the planet by the force of gravity.

56
Q

What is the composition of the atmosphere?

A

The atmosphere is composed of:
- Nitrogen 78%
- Oxygen 21%
- Other gasses 1%

57
Q

What does ISA stand for?

A

ISA stands for International Standard Atmosphere.

58
Q

What are the ISA mean sea level values?

A

ISA mean sea level values are:
- 1013.25 hPa
- 15 °C

59
Q

What is the environmental lapse rate (ELR) in ISA?

A

The environmental lapse rate (ELR) is -2°C per 1000 feet.

60
Q

What is the ISA pressure lapse rate?

A

The ISA pressure lapse rate is -1 hPa per 30 feet.

61
Q

How do we measure air pressure?

A

Air pressure is measured using a barometer.

62
Q

What are the two main types of barometers?

A

The two main types of barometers are:
1. Mercury Barometer
2. Aneroid Barometer

63
Q

What conditions are associated with low pressure?

A

Unsettled weather and weather fronts.

64
Q

What conditions are associated with high pressure?

A

Calm and settled conditions.

65
Q

How does wind flow around a low-pressure system in the southern hemisphere?

A

Clockwise.

66
Q

How does wind flow around a high-pressure system in the southern hemisphere?

A

Anti-clockwise.

67
Q

What are the three stages of a typical cyclone?

A

Developing stage, Mature stage, Rain depression stage.

68
Q

What are high pressure systems also called?

A

Anticyclones.

They are typically larger than low pressure systems and are associated with calm and settled weather conditions.

69
Q

What is an inversion?

A

When hot air rises, cools, becomes denser, and sinks, preventing smoke and dust from rising.

70
Q

What are radiation inversions?

A

Temperature inversions that form at night when the earth loses heat through terrestrial radiation.

A thin layer of air becomes cold, leading to an increase of temperature with altitude.

71
Q

What are valley inversions?

A

Inversions that form in valleys from cooling of the earth and nocturnal katabatic winds.

72
Q

What are frontal inversions?

A

When warm air spreads over a layer of cooler air or when cooler air is forced beneath a layer of warmer air.

73
Q

What are troughs?

A

V-shaped extensions of isobars in a low-pressure system where air flows in and begins to rise.

74
Q

What is a ridge?

A

U-shaped extension of isobars in a high-pressure system maintaining settled weather.

75
Q

What is a col?

A

A natural area of nearly constant pressure between opposing systems, often associated with light winds.

76
Q

In which direction does wind flow?

A

From high pressure to low pressure, driven by the pressure gradient force.

77
Q

What is the Coriolis Force?

A

It causes the wind to turn to the left in the southern hemisphere.

78
Q

What is backing in terms of wind direction?

A

Wind direction change that is anti-clockwise.

79
Q

What is veering in terms of wind direction?

A

Wind direction change that is clockwise.

80
Q

What are anabatic winds?

A

Winds created when air heats on a mountain slope and gradually flows up the hill.

81
Q

What are katabatic winds?

A

Winds formed when cooler, denser air flows down mountain slopes at night.

82
Q

What is the Venturi effect?

A

An increase in wind speeds by up to 100% when wind is funneled through a narrow passage like a valley.

83
Q

What is a sea breeze?

A

A breeze occurring near coastal regions due to temperature and pressure changes over the course of a day.

84
Q

What does a TAF provide, and for how long is it typically valid?

A

A TAF provides weather forecasts for aerodromes, typically valid for 9, 12, or 30 hours.

85
Q

In a TAF, what does the abbreviation FM mean?

A

FM stands for From, indicating a significant change in weather conditions beginning at the specified time.

86
Q

How is visibility expressed in a TAF, and what does 9999 signify?

A

Visibility is given in meters, and 9999 means visibility is 10 km or more.

87
Q

What does PROB30 mean in a TAF?

A

It indicates a 30% probability of the specified weather event occurring.

88
Q

What type of information does a GAF provide?

A

A GAF provides graphical forecasts for weather conditions over a large area, including cloud cover, visibility, icing, and turbulence.

89
Q

In a GAF, what do the abbreviations ISOL, OCNL, and FREQ refer to?

A

ISOL: Isolated (affecting less than 50% of the area).

OCNL: Occasional (affecting 50-75% of the area).

FREQ: Frequent (affecting more than 75% of the area).

90
Q

What is indicated by the symbol CB in a GAF?

A

CB stands for Cumulonimbus, associated with thunderstorms, turbulence, and possible severe weather.

91
Q

How are freezing levels displayed in a GAF?

A

Freezing levels are marked as a height in feet, such as FL050, meaning 5000 feet.

92
Q

What does a METAR report provide?

A

A METAR provides current weather observations at an aerodrome, including wind, visibility, weather, clouds, temperature, dew point, and QNH (pressure).

93
Q

In a METAR, what does SCT025 mean?

A

SCT025 means scattered cloud at 2500 feet above the aerodrome level.

94
Q

What does the abbreviation CAVOK in a METAR indicate?

A

CAVOK means no significant weather, visibility of 10 km or more, and no cloud below 5000 feet or the highest minimum sector altitude.

95
Q

What is a SIGMET, and when is it issued?

A

A SIGMET is issued to warn pilots of significant weather phenomena such as severe turbulence, icing, thunderstorms, or volcanic ash.

96
Q

In a weather briefing, what does the abbreviation GWPT stand for?

A

GWPT stands for Graphical Wind and Temperature Prognosis, showing forecast winds and temperatures at different flight levels.

97
Q

On a weather chart, what do isobars represent?

A

Isobars represent lines of equal atmospheric pressure, indicating wind strength and direction.

98
Q

What information does a MIST chart provide?

A

A MIST chart provides observations of weather conditions, such as fog or mist, that may affect visibility.

99
Q

What is the significance of the symbol TS on weather charts?

A

TS stands for Thunderstorm, indicating possible severe weather, heavy rain, and turbulence.

PPL (11 decks)

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