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Ground School - Aviation > Meteorology Part 2 > Flashcards

Meteorology Part 2 Flashcards

1
Q

Temperature

A

Standard temperature is 15 degrees C at sea level.
Temperature tends to decrease approximately 2 C / 1000 ft.

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2
Q

Advection

A

Air flowing from a cold area over a warm area experiences heating from below by the earth’s warmer surface.

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3
Q

Convection

A

Air over a warm surface rises rapidly, and cool air takes it’s place where it is also heated.

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4
Q

Mechanical Turbulence

A

Wind blowing over rough terrain breaks up into whirls and eddies, causing a mixing of air and spreading surface heat into the air aloft.

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5
Q

Compression

A

Air comes under increased atmospheric pressure resulting in the air being heated.

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6
Q

Thermals

A

Heated from below, these rising currents of air create “free lift,” allowing aircraft-like gliders to fly for extended periods of time without engine power.
–most noticeable in hotter conditions near mountainous terrain.

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7
Q

heating

A

Advection
Convection
Turbulent Mixing
Compression

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8
Q

cooling

A

Radiation
Advection
Expansion

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9
Q

Radiation

A

At night, air in contact with the cooler earth will also be cooled.

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10
Q

Advection

A

Air from a warm region moves over a cool region.

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11
Q

Expansion

A

When air is forced to rise, it encounters a lower pressure and expands. This causes the air temperature to decrease

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12
Q

Horizontal Temperature Differences

A

Land = heats readily & loses heat quickly.
Water = hard to heat up & longer to cool down.

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13
Q

Temperature Inversions

A

Inversion – An increase in temperature with an increase in height.

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14
Q

3 common scenarios that produce temperature inversions

A

1) Radiation Inversion

2) Subsidence Inversion

3) Frontal Inversion

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15
Q

Radiation Inversion

A

At night, air near the ground cools by radiation. Cold dense air lies along the ground and is covered by a warmer layer above. This situation consists of stable air, (little vertical movement), and light to no wind.

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16
Q

Subsidence Inversion

A

Subsiding air well above the earth’s surface (8000 ft or higher) descends and warms adiabatically.

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17
Q

Frontal Inversion

A

During the advance of a cold front, a mass of warm air may be lifted over top of a colder, denser air mass creating a warm layer of air aloft.

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18
Q

Isothermals

A

Lines joining areas of equal temperature.

Isotherms are like isobars, except they show temperature, not pressure.

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19
Q

Humidity

A

The amount of moisture in the air.

The amount of moisture a given volume of air can absorb depends on its temperature. (because cold the molecules are together = no space for moisture)

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20
Q

Relative Humidity

A

The actual amount of moisture in the air, compared to the amount that it could hold at that temperature.

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21
Q

Dew Point

A

The temperature to which air must be cooled at a constant pressure to reach a state where it can hold no more water vapor.

At this point, the air contains 100% of the moisture it can hold, and is said to be saturated.

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22
Q

Temperature / Dew Point Spread

A

The temperature difference
between air temperature & dew point temperature.

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23
Q

The smaller the dew point spread =

A

the higher the relative humidity, the closer to clouds, fog and precipitation forming.
This number is of critical importance when night flying
If the temperature-dew point spread is within 2 or 3 degrees, you may takeoff in clear skies and return to find fog.

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24
Q

Lapse Rate

A

The rate of temperature decrease with height.
ISA lapse rate = 1.98°C / 1000 ft. assumes standard conditions.
–usually between Dry & Saturated adiabatic lapse rate.

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25
Q

Dry Adiabatic Lapse Rate (DALR)

A

The rate of temperature decrease with height of dry or unsaturated air.

Dry air cools at a rate of 3°C/1000 ft

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26
Q

Saturated Adiabatic Lapse Rate (SALR)

A

The rate of temperature decrease with height of wet or saturated air.

Wet or Saturated air cools at a rate of 1.5°C/1000 ft

aka: moist adiabatic lapse rate (MALR)

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27
Q

Cloud height can be found using:

A
  1. Surface temp.
  2. Dew point
  3. DALR
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28
Q

Freezing level can be found using

A
  1. Cloud height
  2. SALR
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29
Q

The environmental lapse rate (ELR),

A

decrease of temperature with altitude at a given time and location.

Put simply, it is what is actually happening with the lapse rate.

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30
Q

This is a STABLE environment (air)

A

Air that is forced to rise and is cooler than the surrounding air will sink back down again because it is more dense.

ELR is less than the DALR = stable air

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31
Q

This is an UNSTABLE environment. (air)

A

Air forced to rise that is warmer than the surrounding air will continue to rise as it is warmer and less dense.

ELR is greater than the DALR = unstable air

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32
Q

Steep Lapse Rate:

A

The temperature decreases rapidly with height.

Implies unstable air.

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33
Q

Shallow Lapse Rate:

A

temperature decreases slowly with height.

Implies stable air.

34
Q

Modification of Lapse Rates (Made U N S T A B L E )

A

Warming from Below:
1) Day time heating
2) Advection [Cold air moving over a warm surface is heated from below]
Cooling Above:
1) rapidly moving cold front - air moves up = unstable

35
Q

Modification of Lapse Rates (Made S t a b l e )

A

Cooling from Below
1) Night time
2) Advection [Warm air moves over colder ground = cools down]
Heating Above
1) Warm Fronts - gradual heating = more stable.

36
Q

Characteristics of Stable & Unstable Air
–Visibility

A

Stable = Poor visibility/ May be smog or smoke/ Mist or fog
UNstable = Typically Clear

37
Q

Characteristics of Stable & Unstable Air
–Cloud

A

Stable = Layer type cloud/ Steady precipitation
UNstable = Heap type cloud/ Showery precipitation

38
Q

Characteristics of Stable & Unstable Air
–Wind

A

Stable = Steady and light
UNstable = Potentially more gusty/ Stronger winds

39
Q

Characteristics of Stable & Unstable Air
–Turbulence

A

Stable = Smooth
UNstable = more turbulent –> Convective turbulence/
Clear air turbulence

40
Q

Five Lifting Processes (forming clouds)

A

1) Convection
2) Orographic lift
3) Frontal lift
4) Mechanical lift
5) Convergence

41
Q

Orographic Lift (to form a cloud)

A

Wind or air that suddenly meets rising terrain will be deflected upward, and continue to rise if the air is unstable.

42
Q

Frontal Lift (to form a cloud)

A

A front is the boundary zone between a warmer air mass and colder air mass.

When met with colder denser air, a warm air mass will be lifted on top of the colder, denser air mass.

43
Q

Mechanical Lift (to form a cloud)

A

Friction with larger terrain (mountains, hills, buildings, trees), will cause turbulent eddies, lifting air near the surface to higher levels.

44
Q

Convergence (to form a cloud)

A

Winds blow toward the centre of a low pressure area.
Air in this convergent zone is forced to rise.

45
Q

Convection (to form a cloud)

A

Air is heated through coming in contact with the earth and forms columns of rising air.

unequal heating of different surfaces = clouds in some spots with more moisture.

46
Q

3 things must be present to form a cloud:

A

1) Water Vapor -Relative humidity near 100% (temperature equals dew point).

2) Condensation Nuclei: Water vapor must have something to attach to such as dust, smog particles, or smoke particles.

3) Cooling Process: Due to radiation, advection, expansion etc.

47
Q

Cloud Categories

A

Cumuliform Cloud
Stratiform Cloud
Nimbus Clouds

48
Q

Cumuliform Cloud

A

vertical development
heaped /puffy clouds
unstable air

The size = the instability of the air.
The greater the instability = higher the current rises = higher the cloud extends.

49
Q

Stratiform Cloud

A

stable air is cooled below its saturation point.
There is little or no vertical motion.

50
Q

Nimbus Clouds

A

precipitation falls.

51
Q

Cloud Categories

A

Low cloud – Below 6,500’ AGL
Middle cloud – 6,500’-20,000’ AGL
High cloud – Above 20,000’ AGL
Vertical Development

52
Q

Low cloud – Below 6,500’ AGL

A

Stratus (St)
Stratocumulus (Sc)
Nimbostratus (Ns)

53
Q

Middle cloud – 6,500’-20,000’ AGL

A

Altocumulus (Ac)
Altostratus (As)

54
Q

High cloud – Above 20,000’ AGL

A

Cirrus (Ci)
Cirrostratus (Cs)
Cirrocumulus (Cc)

55
Q

Vertical Development - cloud types

A

Cumulus (Cu)
Cumulonimbus (Cb)
Altocumulus Castellanus (Acc)
Towering Cumulus (Tcu)

56
Q

Cloud Types - Cirrostratus

A

often create a halo effect around the sun or moon.

57
Q

Cloud Types - Cirrocumulus

A

high-level puffy cirrus clouds are rolled in appearance and
composed entirely of ice crystals.

58
Q

Cloud Types - Cumulus

A

low level clouds are indicative of fair weather.
They are dense clouds of vertical development.

59
Q

Cloud Types – Towering Cumulus

A

These are very large cumulus clouds that may produce significant turbulence or showers.
**TCUs are to be avoided.

60
Q

Cloud Types – Altocumulus Castellanus

A

somewhat uncommon cumuliform clouds are named for their castle-like or turreted appearance.

61
Q

Cloud Types – Cumulonimbus

A

largest of all cumuliform clouds
–produce virtually every meteorological hazard to aviation
–including thunderstorms.

62
Q

Cloud Types – Mammatus Clouds

A

extremely rare clouds are characteristic of descending air masses

63
Q

Cloud Types – Rotor Clouds

A

Part of a mountain wave, rotor clouds are indicative of severe turbulence

64
Q

Cloud Types – Lens Clouds

A

Also part of a mountain wave, lens clouds are indicative of severe turbulence.

65
Q

Cloud Types – Contrails

A

Technically clouds, contrails are frozen ice crystals formed as a bi-product of fuel combustion.

66
Q

Precipitation

A

All moisture that falls from the sky is precipitation

100% humidity doesn’t guarantee precipitation –> Most clouds don’t precipitate ;)

67
Q

Causes of Precipitation

A

Coalescence - Droplets collide to form a larger droplet.

Ice Crystal Process – Ice crystals grow from the water vapor given up by evaporating water droplets and eventually fall from clouds as snow.

68
Q

Precipitation from clouds : Ns, As

A

Snow, rain, continuous

69
Q

Precipitation from clouds: Sc, Ac

A

Snow, rain intermittent

70
Q

Precipitation from clouds: Cb, TCu, Acc

A

Snow, rain showery

71
Q

Precipitation from clouds: Cb , TCu

A

Snow pellets, ice pellets, hail

72
Q

Precipitation from clouds: Clear sky

A

Ice crystals

73
Q

Surface Based Layers (fog vs. mist)

A

ground based layer = FOG if visibility = < 5/8th of statute mile
ground based layer = MIST if visibility = > 5/8th of statute mile

74
Q

Fog - cloud layer based on the ground
ideal conditions = (3)

A

1) High relative humidity
2) Abundance of condensation nuclei
3) Process to create condensation

75
Q

Fog Types (6)

A

Radiation Fog
Advection Fog
Upslope Fog
Steam Fog
Ice Fog
Frontal Fog

76
Q

Radiation Fog

A

Night = ground cools by radiation = cools air directly above it.
If the air is moist & temp decreases below dew point = fog

Conditions: On land, Light winds, Clear skies, Moist air

77
Q

Advection Fog

A

cooling of moist air flowing over a surface colder than itself

78
Q

Upslope Fog

A

forms (up mountains) orographically due to the cooling of moist air by expansion, as it moves up a slope

79
Q

Steam Fog

A

Forms when water vapour is added to the air

80
Q

Ice Fog

A

Formed of ice crystals.
Water vapour added through fuel combustion (ex: tailpipe)

81
Q

Frontal Fog

A

Forms when rain falling from warm air evaporates and saturates the cooler air below.

Ground School - Aviation (11 decks)

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