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PRIVATE PILOT > Weather Theory > Flashcards

Weather Theory Flashcards

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Charter Pilot (Part 135) - Oral flashcards
1
Q

Atmospheric Composition

A

78% Nitrogen
21% Oxygen
1% Other

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2
Q

Troposphere

A

Lowest level of atmosphere.

Nearly all weather occurs here.

As altitude goes up temperature goes down.

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3
Q

Tropopause

A

Boundary between Troposphere and Stratosphere.

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4
Q

Stratosphere

A

Temp gradually increases as altitude goes up.

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5
Q

Standard Atmosphere

A

Datum for temperature and pressure at specific altitudes.

At sea level standard is:
15 Degrees C
29.92 hg

Lapse rate is every 1000ft up you drop 2 degrees C.

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6
Q

Indicators of Stable Atmosphere

A

Poor visibility
Stratiform Clouds
Continuous Precipitation
Absence of Turbulence

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7
Q

Indicators of UNstable Atmosphere

A

Good visibility
Cumuliform Clouds
Scattered Precipitation
Turbulent Air
Thunderstorms

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8
Q

What is convection?

A

Upward and downward movement of air.

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9
Q

Three forces affecting wind heading and speed?

A

Pressure Gradient Force

Coriolis Force

Friction

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10
Q

How does pressure travel?

A

High to Low

Carries winds

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11
Q

What is Wind Shear?

A

Air Currents of differing velocities create friction or Shear between them. Inside the shear zone is a nasty mix of eddies and whirls.

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12
Q

Temperature Inversion

A

May exist anywhere

Most commonly found on clear, calm, cool nights.

The land cools more rapidly than the air, cooling the air directly above it faster than the air aloft.

May cause poor visibility.

May cause structural Icing.

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13
Q

What does evaporate mean?

A

Turn to vapor

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14
Q

What is humidity?

A

Moisture in the air

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15
Q

What is relative humidity?

A

Saturation level of the air, expressed as a %

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16
Q

What is Dew Point?

A

The Temperature at which the are would become 100% saturated by the moisture already present.

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17
Q

What is Temperature-Dew Point Spread?

A

Current Temperature - Current Dew Point

If spread is = 0 degrees, the relative humidity is 100%

Typically a Surface Spread Less than or equal to 5 degrees C will result in fog.

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18
Q

What is condensation?

A

Vapor to liquid

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19
Q

What is Sublimation?

A

Vapor straight to Ice

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20
Q

What is Super-Cooled Water?

A

Unfrozen water at a temperature below 0 degrees C

May freeze upon impact, causing structural icing.

If dew point is less than 0 deg C, water vapor tends to skip the liquid stage.

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21
Q

What is an Air Mass?

A

Large body of air having fairly uniform properties of temperature and moisture.

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22
Q

Types of Air Masses by Temperature?

A

Arctic - cold air formed over large bodies of ice or snow, typically at the poles.

Polar - cool air from the upper latitudes

Tropical - Warm air from the lower latitudes and equatorial areas.

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23
Q

Types of Air Masses by Moisture Content?

A

Continental - Formed over land,

Maritime - Formed over water.

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24
Q

5 Possible Classifications of Air Masses?

A

Continental Arctic - Cold, Dry

Continental Polar - Cold, Dry

Continental Tropical - Hot, Dry

Maritime Polar - Cool, Moist

Maritime Tropical - Warm, Moist

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25
Q

What is a Front?

A

Zone in between two Air Masses.

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26
Q

What might you experience at a Front?

A

Wind direction, speed or both may change rapidly.

Possible wind shear

Temperature changes rapidly

Pressure changes rapidly

Altimeter settings change rapidly

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27
Q

What is a Cold Front?

A

Leading edge of advancing cold air mass.

28
Q

What happens when a cold air mass encounters a warm air mass at the surface?

A

A cold front will replace the less dense warm air mass.

29
Q

What is a Warm Front?

A

Leading edge of advancing Warm air mass.

Typically move half as fast as a Cold Front.

30
Q

What is an Occluded Front?

A

Faster Cold Front overtakes slower Warm Front.

31
Q

What is a Squall Line?

A

Narrow band of fully developed Thunder Storms

32
Q

What is a Dry Line?

A

Low Level Boundary separating moist air from dry air.

33
Q

Height for low clouds?

A

Surface - 6500ft

34
Q

Height for middle clouds?

A

6,500 - 23,000ft

35
Q

Height for High clouds?

A

16,500 - 40,000ft

36
Q

Cumulus clouds

A

Big, lumpy, billowy clouds

cumulus = accumulation

Result of convection

Typically indicate unstable atmosphere

37
Q

Stratus clouds

A

Uniform, sheet like clouds

Result of stable air cooling

38
Q

Nimbus clouds

A

Clouds from which rain is falling

39
Q

Fractus clouds

A

clouds broken into fragments

40
Q

High altitude clouds

A

Cirrus

Cirrocumulus

Cirrostratus

All typically thin and white in appearance

41
Q

Mid Altitude Clouds

A

Altocumulus - wave pattern

Altostratus - Cover the sky allowing very little light.

42
Q

Low altitude clouds

A

Stratus

Stratocumulus

Nimbostratus

Cumulus

43
Q

Clouds with extensive vertical development

A

Towering Cumulus

Cumulonimbus

44
Q

Convective Turbulence

A

Result of uneven heating of Earth’s surface

45
Q

Mechanical Turbulence

A

Obstructions to wind flow causes turbulence

46
Q

Mountain Wave turb

A

Wind forms a wave pattern after passing over mountain

47
Q

Wake turbulence

A

Fall downward and outward

Carried by wind if any

48
Q

What needs to be there for a Thunder storm to form?

A

Sufficient moisture

Unstable atmosphere

Updrafts

49
Q

How do updrafts occur?

A

Surface heating

Winds pushed up sloping terrain

Converging winds

All of the above

50
Q

Three stages of Thunder Storm

A

Cumulus

Mature

Dissipating

51
Q

Cumulus Stage

A

Characterized by updrafts

Growth rate up to 3000 FPM

The cloud and rain drops grow in size

52
Q

Mature Stage

A

Characterized by Precipitation, Updrafts, and Downdrafts.

Extremely powerful downdrafts = Microburst

Thunderstorm hazards reach greatest effect.

53
Q

Dissipating Stage

A

Characterized by Downdrafts

Storm dies rapidly

No rain/downdrafts = no more thunderstorm

54
Q

Microbursts

A

An extremely powerful downdraft

May occur anywhere thunderstorms, precipitation, or virga occurs.

Typically lasts 10 - 20 min

Most dangerous when landing

No known techniques can get you out of one.

55
Q

Three types of icing?

A

Induction Icing

Instrument Icing

Structural Icing

56
Q

Induction Icing

A

Ice accumulation blocking air from reaching the engine.

57
Q

Instrument Icing

A

Icing of the pitot tube and or static source

Causes erroneous reading of:

  • Airspeed Indicator (ASI)
  • Altimeter
  • Vertical Speed Indicator (VSI)
58
Q

Structural Icing

A

Visible Moisture

Super-cooled water droplets may increase rate of structural icing.

Three Types:

  • Clear - Forms when water droplet continues to spread, freezing slowly. Smooth sheet of heavy, and hard ice. Most dangerous.
  • Rime - Formed by smaller droplets freezing rapidly. White, opaque appearance. Rough surface.
  • Mixed - Combination of clear and rime ice. Heavy and rough.
59
Q

PAIRUS Acronym for Fog

A

Precipitation

Advection

Ice

Radiation

Upslope

Steam

60
Q

Precipitation fog

A

Forms as warmer precipitation falls through colder air, saturating the air as it evaporates.

61
Q

Advection fog

A

Forms as moist air moves over colder ground or water.

62
Q

Ice fog

A

fog composed of Ice cyrstals

63
Q

Radiation fog

A

Terrestrial radiation from the cooling ground cools the air above it.

64
Q

Upslope fog

A

Forms as moist stable air is pushed up sloping terrain.

65
Q

Steam fog

A

Forms when cold air moves over warm water.

PRIVATE PILOT (30 decks)

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