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Weather > Weather > Flashcards

Weather Flashcards

1
Q

Reference pubs

A

AIM
FIH

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2
Q

Atmosphere composition

A

78% Nitrogen
21% Oxygen
1% other

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3
Q

Troposphere

A

-Adjacent to surface (28k-55k AGL) (36k’ US)
-temp dec w altitude
-winds inc w altitude
-nearly all weather occurs here

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4
Q

Pressure

A

Ambient static pressure is measured by weight of a column of air above Earth’s surface

Always dec w altitude

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5
Q

2 units for pressure

A
  1. Inches of Mercury (“ Hg)
  2. millibars (mb)
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6
Q

Standard pressure lapse rate

A

1” Hg lost per 1,000 ft alt

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7
Q

Pressure gradient force

A

As pressure is exerted on Earth’s surface it moves outward in either ascending or descending manner

Air moves from areas of high pressure to low pressure

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8
Q

PGF (high pressure)

A

Descending air

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9
Q

PGF (low pressure)

A

Ascending air

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10
Q

How far are isobars separated

A

4 mb pressure

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11
Q

Standards at sea level

A

29.92” Hg
15 C (59 F)

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12
Q

Temp lapse rate

A

2 C/1,000 ‘

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13
Q

Sea level pressure

A

SLP is the pressure read directly at sea level or calculated from known station pressure

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14
Q

Station pressure

A

SP is atmospheric pressure read directly at an airfield or specific altitude

Will always be less than equivalent sea level pressure when station is above sea level

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15
Q

SLP= SP+FE

A
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16
Q

Types of altitudes

A

Indicated
True (MSL)
Absolute (AGL)
Density
Pressure

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17
Q

Indicated altitude

A

Simply what altitude indicates

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18
Q

True altitude (MSL)

A

Height above mean sea level. This is standard altitude used

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19
Q

Absolute altitude (AGL)

A

Height above terrain below you

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20
Q

Density altitude

A

Not displayed on altimeter, calculated to determine the altitude the airplane “thinks” it’s at. Used for performance purposes

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21
Q

Pressure altitude

A

Altitude displayed when 29.92 is set in the Kollsman window (standard altitude setting in class A airspace 18k ft and above)

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22
Q

What does the altimeter measure

A

Measures the difference between the static pressure and pressure set in Kollsman window

Calibrated for 1,000 ft change for every 1” Hg diff

Indicated altitude will never match the true altitude whenever the setting in the Kollsman window is incorrect

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23
Q

How does pressure changes affect the altimeter

A

Change in pressure of 1” Hg will change the altimeter by 1,000 ft

Important to update altimeter settings throughout flight
“High to low - look out below”
“Low to high - plenty of sky”

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24
Q

High to low

A

MSL = assigned alt (-) alt error
AGL = MSL (-) field elevation
Indicated alt on deck = field elevation (+) alt error

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25
Q

Low to high

A

MSL = assigned alt (+) alt error
AGL = MSL (-) field elevation
Indicated alt on deck = field elevation (-) alt error

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26
Q

Effects of temp deviations on altimeters

A

If colder than standard atmosphere, altitude will indicate higher altitude

If warmer than standard atmosphere, alt will indicate lower alt

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27
Q

Air masses

A

Large body of air with relatively same temp and moisture across a horizontal plane

Named for temp relative to surface

Temp, location, moisture for naming

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28
Q

What causes circulation and how does it affect the air

A

Constant heating and cooling of the Earth’s surface leads to ascending and descending air

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29
Q

Dew point

A

Amount of moisture in air

Air is saturated when temp = dew point

Cold air holds less moisture

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30
Q

Dew point spread

A

As spread dec, moisture will begin to condense and become visible

Visible moisture forms frost, fog, clouds

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31
Q

Effects of temp deviations on altimeters

A

If colder than standard atmosphere, altimeter will indicate higher altitude (MSL lower)

If warmer than standard atmosphere, altimeter will indicate lower altitude (MSL higher)

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32
Q

What’s an air mass and what’re they named for

A

Large body of air w relatively same temp and moisture across a horizontal plane

Named for temp relative to surface,

temp, location, moisture for naming

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33
Q

Stability vs type of air mass

A

Cold air mass = unstable
Warm air mass = stable

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34
Q

What is weather the result of

A

Heat exchange

Compounded by spinning of earth (Coriolis effect)

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35
Q

What is relative humidity

A

Relative humidity is not direct measurement of the actual amount of water vapor/moisture, only the actual amount in the air compared to the amount that could be present if saturated

The closer you get to 100% more likely you’ll see visible moisture

Warmer air can hold more moisture than cold air

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36
Q

What are two key elements in pre flight planning

A

Temperature and dewpoint

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37
Q

Temperature inversion

A

Temperature normally decreases as you gain altitude. However sometimes temperature can increase as you gain altitude

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38
Q

What is pressure gradient force

A

Driving force of all wind

Descending air result in high pressure and flows outward away from high-pressure center

Ascending air result in low pressure and flows inward toward the low pressure center

“Out of the highs and into the lows”

Winds don’t travel the same direction pressure does due to Coriolis effect

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39
Q

What are gradient winds

A

Found above 2000 AGL and flow parallel to how the isobars are depicted on a surface chart

Clockwise around high-pressure centers

Counter clockwise around low pressure centers

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40
Q

What are surface winds

A

Heavily influenced by surface friction and found below 2000 AGL

Do not flow exactly parallel to the isobars due to surface friction

Surface winds around low pressure center will tend to turn towards center

Surface winds around high pressure center tend to turn away from center

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41
Q

What is a jet stream

A

Average height is 30,000 feet

generally flows west to east

Average speed is 100 to 150 kts

100 to 400 miles wide

1000 to 3000 miles long

3000 to 7000 feet thick

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42
Q

What is Seabreeze

A

Cool dense air over water moves over warm land during day

Air warms rises and returns over ocean

Usually 1500 feet to 3000 feet AGL and 15 to 20 kts

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43
Q

What is land breeze

A

Land cools faster than water so now water is warmer causing the cycle to reverse as result

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44
Q

What’s a front

A

Discontinuity between contrasting air masses

 specific discontinuities used to locate  classify fronts are:

Temperature, dew point, wind, pressure

“Touch downs win playoffs”

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45
Q

What is a cold front

A

Colder, more dense air moves into warm air (bulldozer)

Cool air slide underneath forcing warm air up

results in unstable conditions, cumuliform clouds, showery precipitation

46
Q

What is the squall line

A

Line of fast-moving thunderstorms

Often develop 50 to 30 miles in front of cold fronts

Contain severe hazards to aviation

47
Q

Warm front

A

Warm air overtakes cooler air, usually slower

Results in stable condition prior to passage, stratiform clouds, little to no turbulence, continuous precipitation

48
Q

Stationary front

A

Alternating cold/warm front symbols pointing in opposite direction

Can align any direction

Weather conditions similar to that of warm front, but often less intense

49
Q

Occluded front

A

Cold front overtakes warm front

Wind shifts 180° from south east to north west

Weather associated with both warm/cold fronts over wide areas

50
Q

What determines stability

A

Temperature of the surrounding air



51
Q

Stable

A

Colder air settles when lifting action removed

52
Q

Unstable

A

Warmer air continues to rise

53
Q

Neutrally stable

A

Same temperature air simply remains at point where lifting action was removed

54
Q

Cloud types

A

Stratiform

Cumuliform

55
Q

Stratiform clouds

A

Comes from moist stable air and associated with steady precipitation

Widespread with no definable shape

56
Q

Cumuliform clouds

A

Comes from moist unstable air and associated with showery precipitation

Large puffy clouds with more definite shapes and vertical development

57
Q

Precipitation characteristics

A

Showery: Sudden start and stop, abrupt intensity changes, cumuliform type clouds

Continuous: with gradual change, Stratiform clouds

Intermittent: Starts/Stops at least once during the hour, either type cloud

58
Q

Special clouds (Extensive vertical development)

A

Nimbo/Nimbus: Violent or heavy

Cumulonimbus (thunderstorms):

Severe to extreme turbulence, hail, icing, lightning, bases at low altitude, tops at high altitudes

Nimbostratus:

Thick, uniform, widespread clouds that build downwards. Heavy rain showers and moderate turbulence, no thunder

59
Q

What are the three cloud groups

A

Low, middle, high

60
Q

Low cloud group

A

SFC – 6500 feet AGL

No prefix

Stratus/cumulus

61
Q

Middle cloud group

A

6500 feet AGL to 20,000 feet AGL

“Alto”

Altostratus/altocumulus

62
Q

High cloud group

A

> 20,000 feet AGL

“Cirro” zero chance icing

Cirrostratus/cirrocumulus


63
Q

What are the four lifting methods

A

Frontal

Orographic

Convergence

Thermal

64
Q

Frontal lifting

A

Only deals with cold fronts fronts

65
Q

Orographic lifting

A

Anything on ground lifting air

Ex. Mountains and hills

66
Q

Convergence lifting

A

Air flowing hitting other air masses

67
Q

Thermal lifting

A

Warm air rising up

68
Q

Flight conditions: F.A.T V.IP Wants Chow

A

Fronts
Air mass
Turbulence
Visibility
Icing
Precipitation
Winds
Cloud types

69
Q

What Would Sarah Palin Repeat, Something Silly Stupid

A

“Stable atm conditions”
Warm
Warm
Smooth
Poor
Rime
Steady
Steady
Stratus

70
Q

Captain Crunch Really Good Cereal Super Good Cereal

A

“Unstable atm conditions”

Cold
Cold
Rough
Good, Outside of clouds
Clear
Showery
Gusty
Cumulus

71
Q

Turbulence

A

Irregular or disturbed atmospheric flow producing gust and or eddies

Most hazardous at low altitude

72
Q

Intensity classification for hazards

A

Light
Moderate
Severe
Extreme ( declare emergency, exit area asap or you gonna die)

73
Q

Reporting duration of turbulence

A

Occasional (Less than 1/3 of the time)

Intermittent (1/3 to 2/3 of the time)

Continuous (More than 2/3 of the time)

74
Q

What are the different types of turbulence

A

Thermal

Mechanical

Frontal

Large scale wind shear

75
Q

Thermal turbulence

A

Results from the heating below

Strength depends on the type of surface being heated

76
Q

Mechanical turbulence

A

When buildings or ground objects interfere with normal wind flow; Usually no more than 1000 feet AGL

Can occur with hills/valleys

Depends on the speed of the wind, roughness of terrain, instability of air

77
Q

Frontal turbulence

A

The result of frontal lifting that is associated with the passage of a cold front

Most prominent in fast-moving cold fronts

Little to no lifting associated with warm front, therefore no frontal turbulence associated with warm fronts

78
Q

Wind shear turbulence

A

Sudden, drastic change in windshear and or direction that can occur anywhere

High level – associated with clear air turbulence like jetstream

Low level – “LLWS” (Most dangerous) due to local phenomenon such as a temperature inversion (temp inversion near surface can cause wind shear)

79
Q

How to penetrate turbulence

A

(Don’t chase airspeed/altitude and maintain good attitude)

  1. Maintain power setting consistent w aircraft’s recommended airspeed for turbulence penetration
  2. Trim aircraft for level flight
  3. Do not chase airspeeds or altitude variations
  4. Maintain pitch and bank (good attitude) VFR scan when conditions permit
80
Q

What are the requirements for icing

A

Visible moisture, free air temperature below freezing

81
Q

What are the three kinds of ice

A

Clear ice

Rime ice

Mixed ice

82
Q

What is clear ice

A

0°C to -10°C (unstable conditions)

Freezing rain, large droplets, cumulus clouds, most severe, difficult to remove

Freezes slowly after spreading out and altering the shape of the wing

83
Q

What is rime ice

A

Stratus clouds, tiny droplets that freeze instantly

84
Q

What is Mixed ice

A

-8°C to -15°C

Combo of two

Most common icing

85
Q

What are the 3 kinds of icing

A

Structural icing

Engine icing

Ground icing

86
Q

What is structural icing

A

Most hazardous aspect is aero effect on airfoils, changes shape

87
Q

What is engine icing (2 types)

A

Compressor
- Can cause imbalance on compressor vanes
-Result in ice ingestion, resulting in FOD Hazard

Induction
-Results in restricted airflow into inlet, flameout
-Can occur in a high humidity at times up to +10°C

88
Q

Reporting (PIREDs)

A

“I Want RUM”

I: conditions on IFR approach differ from the latest observation

W: Wind shear encountered on T/O or LDNG

R: when Requested

U: when Unusual/Unforecasted conditions encountered

M: Missed approach

89
Q

Ground icing

A

Frost
- occurs on ground and you shall remove prior to flight
-no scraping the windshield

You need clear night, no wind, dew point below freezing



90
Q

What could happen when taxiing through water

A

The water could quickly freeze as you gain altitude

91
Q

Effects on breaking action on runway

A

May have to extend landing roll out

Do not fly in icing conditions

92
Q

What is visibility

A

Ability to see prominent unlighted objects during day and prominent lighted objects at night

93
Q

Types of visibility phenomena

A

Reported obscured when visibility reduced to less than 7 miles

Fog

Haze

Smoke

Rain and drizzle

Snow

Blowing snow, dust, sand

94
Q

What is fog and what’re the 2 types

A

Cloud base within 50 feet of ground

Greater than 20 feet thick

Reduces visibility to less than 5/8 of a mile

radiation
-Nocturnal cooling and sun will dissipate it

Advection
-Cooling of a moving air mass and too thick for sun to penetrate

95
Q

What is the thunderstorm lifecycle

A

Developing stage

Mature stage (where most hazards occur)

Dissipating stage


96
Q

What are the thunderstorm hazards

A

”HI MELT”

Hail

Icing

Microbursts

Extreme turbulence

Lightning

Tornadoes

97
Q

What’s a gust front

A

Dangerous gusty winds that occur 5 to 20 miles in front of an approaching thunderstorm. Never take off or land when thunder storm is approaching

98
Q

What is hail

A

May be carried 10 to 20 miles downwind and in clear air

Can cause severe damage in seconds

99
Q

What are microburst

A

Severe, localized downdraft 2000 to 6000 ft./min.

Producing vortex ring of wind 20 to 200 kts

Severe hazard on takeoff and landing

Usually 5 to 10 minutes, very localized

100
Q

Taking off into microburst

A

IAS rapidly increases due to massive headwind

Natural reaction is to reduce throttle

Loss of airspeed on other side due to massive tailwind

101
Q

Lightning

A

Can strike in clear air outside thunderstorm

Flash blindness may occur

Generally not serious when in aircraft

102
Q

Thunderstorm avoidance recommendations (in this order)

A

Circumnavigate (fly around)

Fly over (1000ft per 10kt wind at top)

Fly under

Fly though (penetrate the lower 1/3 of the storm 4000’-6000’ AGL as the upper 2/3 is most likely to encounter hail and/or icing

103
Q

Flight visibility

A

Ability to see and identify prominent unlighted objects during day and prominent lighted objects at night

104
Q

Prevailing visibility

A

Greatest horizontal visibility throughout at least half of the horizon circle

105
Q

Slant visibility

A

Distance on final when the runway environment is in sight

106
Q

Runway visual range (RVR)

A

Horizontal distance looking down the runway

107
Q

Sky coverage is reported in _____

A

Eights (as you look up)

Height of cloud base given in hundreds of ft AGL

108
Q

Ceiling

A

Lowest broken or overcast layer

May be other clouds of layers above

109
Q

Vertical visibility (VV)

A

Distance seen directly upward from the ground into a total obstruction

Used when sky is totally hidden

Hazardous and greatly affects the slant range visibility

Referred to as an “indefinite ceiling”

110
Q

Describe use of PIREPS (Pilot reports)

A

“I Want RUM”

I: conditions on IFR approach differ from latest observation

W: Wind shear

R: when Requested

U: when Unusual/Unforecasted conditions are encountered

M: Missed approach

Also report:

Cloud bases, tops, layers
Flight visibility
Precipitation
Visibility restrictions
Winds at altitude
Temperatures aloft

Weather (1 decks)

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