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Knowledge Test > 15. Weather > Flashcards

15. Weather Flashcards

1
Q

When is a sea breeze most suitable for soaring?

A

Sea breeze = wind from ocean to shore
In afternoon when land is hotter than water.

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2
Q

If a flight is made from low pressure to high pressure without the altimeter being reset, the altimeter will indicate?

A

Lower than actual altitude

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3
Q

CONDITION most conducive to frost formation?

A

Surface temp below freezing & air temp is below freezing
Sublimation = solid to gas without passing thru liquid state.
Frozen dew is hard and transparent.
Frost is white and opaque.

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4
Q

Conditions resulting in frost?

A

Collecting surface at or below dewpoint of adjacent air. AND
Dewpoint is below freezing.

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5
Q

If outside air temp at a given altitude is warmer than standard, then the density altitude is

A

higher than pressure altitude

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6
Q

Weather condition beneath a low level temp inversion layer when the relative humidity is high?

A

Smooth air, poor visibility, fog, haze, low clouds

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7
Q

An air mass moving inland from the coast in winter is likely to result in

A

Fog
Advection fog Advection happens over land AND water. Radiation is only land.

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8
Q

What is absolute altitude?

A

Altitude above ground level

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9
Q

Stable air mass characteristics

A

Stratiform clouds & fog
Continuous precip
Smooth air
Fair to poor visibility

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10
Q

Unstable air mass characteristics

A

Thunderstorms
Cumuliform clouds
Showery precip
Rough air -turbulence
Good visibility

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11
Q

Why is frost hazardous to flight?

A

Spoils smooth air flow over wind and decreases lift

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12
Q

Clouds, fog, or dew will always form when

A

Water vapor condenses

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13
Q

Temperature inversion results in what weather condition?

A

An increase in temp as altitude increases

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14
Q

An almond or lens shaped cloud that appears stationary but can have winds of 50 knots or more is called?

A

Lenticular

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15
Q

What condition would tend to increase density altitude at a given airport?

A

An increase in air temp

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16
Q

Unstable air mass approaching. Which would not be a concern?
Thunderstorms, turbulent air, stratiform clouds

A

stratiform clouds

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17
Q

Relationship of strong thermal to sink between them.

A

Strong thermal = High sink

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18
Q

If temp and dewpoint spread is small and decreasing and the air temp is 62F, what type of weather is likely to develop?

A

Fog or low clouds

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19
Q

Moist stable air flowing upslope can be expected to ?

A

Stratus type clouds. Upslope fog
Warm stable air up slope = stratiform
Warm unstable air up slope = cumuliform

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20
Q

Condition when indicated altitude = true altitude

A

At sea level with standard conditions.
29.92 & 59F
When altimeter is adjusted to actual barometric pressure.

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21
Q

Steady precipitation preceding a front is an indication of

A

Stratiform clouds with little turbulence.
Stable Warm air overriding a front = stratiform
Unstable Warm air overriding a front = Cumuliform

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22
Q

Moisture is added to air by what two processes?

A

Evaporation and sublimation

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23
Q

Boundary between 2 air masses =

A

Front

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24
Q

Nimbus referring to a cloud means

A

rain cloud

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25
Q

Situation conducive to formation of radiation fog?

A

Warm moist air over flatland areas on clear calm nights

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26
Q

When is advection fog most likely to form

A

Air mass moving inland from the coast in winter

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27
Q

Advection fog

A

Layer of warm moist air moves over a cold surface

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28
Q

Upslope fog

A

Moist air moves up a slope.
Stable air = Stratus
Unstable air = Cumuliform
Requires wind to form

29
Q

Steam Fog / Sea Fog

A

Cold dry air mass moves over warm water. Resembles smoke
Coldest month of the year
Low level turbulence & icing

30
Q

Ice Fog

A

When weather is much below freezing (-25F) and water vapor turns directly into ice crystals.

31
Q

Stable air characteristic?
Stratiform clouds, Unlimited visibility, Cumulus clouds

A

Stratiform clouds

32
Q

Crests of standing mountain waves may be marked by stationary lens shaped clouds known as

A

standing lenticular

33
Q

The amount of water vapor air can hold depends on

A

Air Temperature

34
Q

Clouds are divided into 4 families according to their

A

Height range

35
Q

Where and under what condition can lift be found in stable conditions?

A

Upwind side of slopes when sufficient wind is present

36
Q

What is density altitude?

A

Pressure altitude corrected for non standard temperature

37
Q

When warm moist stable air flows upslope it produces

A

Stratus clouds

38
Q

Which feature is associated with a temp inversion?
unstable layer of air, chinook winds on mtn slopes, stable layer of air

A

Stable layer of air

39
Q

Stable air mass?
poor surface visibility, showery precip, turbulent air

A

Poor surface visibility

40
Q

How to obtain pressure altitude for flights below 18000 MSL?

A

Set Kolsman window to 29.92

41
Q

What measurement can be made to determine the stability of the atmosphere?

A

Actual lapse rate.
high lapse rate = unstable
Low lapse rate = stable
If you are surrounded by an air mass that has a high lapse rate, then any local heating of the ground will allow thermals to develop. If surrounding lapse rate is low, then thermals from local heating will be weak.

42
Q

What is the std lapse rate?

A

2C / 1000’
A high lapse rate indicates greater than normal change in air temp with altitude and is characteristic of Unstable Air

43
Q

What is the DALR?

A

Dry adiabatic lapse rate = 3.0C / 1000’

44
Q

Std T & P at sea level?

A

29.92 “ Hg 59F
1013.2 millibars 15C

45
Q

In flight condition for structural icing to form?
visible moisture,
small temp/dewpoint spread,
stratiform clouds

A

Visible moisture
& temp at or below 32F

46
Q

Highest accumulation rate of structure icing?
Freezing rain, freezing drizzle, cumulus clouds with below freezing temp

A

Freezing rain
Supercooled water freezes on impact with plane. Thunderstorms can create supercooled rain. large supercooled droplets make clear icing very rapid between 0C - -15C

47
Q

Unstable air?
Stratiform clouds, good visibility, poor visibility

A

good visibility

48
Q

Clouds, fog, and dew will always form when

A

water vapor condenses

49
Q

Weather feature will always occur when flying across a front?
stability, type of precip, wind direction

A

wind direction

50
Q

What types of fog depends on wind to exist?

A

Advection and upslope fog

51
Q

Development of thermals depends on

A

solar heating

52
Q

What is dewpoint?

A

The temp that air must be cooled to become saturated

53
Q

The most frequent type of surface based temp inversion is produced by

A

Terrestial radiation on a clear calm night.
Ground radiates heat and cools faster than surrounding air

54
Q

Convective circulation patterns associated with sea breezes are caused by?

A

Land absorbing and radiating heat faster than the water.
Sea breeze = breeze from the sea = afternoon

55
Q

True altitude = ?

A

Vertical distance between plane and sea level

56
Q

One of the most easily recognized discontinuities across a front are?
increase in cloud coverage, increase in RH, change in temp

A

Change in temp

Types of fronts referencing new air to the air its replacing
1. Warm
2. Cold
3. Stationary
4. Occluded

57
Q

What would decrease the stability of an air mass?

A

Heating from below

58
Q

Mtn wave turbulence could be anticipated when 40 knot or higher winds blow?
parallel to mtn and air is stable,
across mtn range and air is stable
down a mountain valley and air is unstable

A

Across a mtn range and air is stable

59
Q

At 5000’ AGL winds are SW. At ground level winds are South. Diff in direction is due to

A

Friction between the wind and the surface.
SFC slows wind. The more rough the terrain the more it affects direction and speed.
Coriolis force deflects air to the right in Northern hemisphere

60
Q

A pilot can expect wind shear zone in a temp inversion when the wind speed at 2000’ - 4000’ AGL is ?

A

25 knots

61
Q

What signals the BEGINNING of a mature stage of a thunderstorm?

A

Precipitation begins to fall.
1. Cumulus stage - clouds increase in vertical height
2. Mature stage - Rain forms and starts falling. Condensing action reduces temp causing downdrafts. Most violent part of thunderstorm.
3. Dissipating - Anvil shape cloud. Downdrafts take over spreading surface winds and lower temps

62
Q

Every physical process of weather is accompanied by or is the result of ?

A

Heat exchange

63
Q

What to do when landing with icing conditions?

A

Fly faster than normal landing & approach speeds

64
Q

The evidence of ice pellets at the surface is evidence that there is ?

A

a temp inversion with freezing rain at a higher altitude

65
Q

Under what conditions will pressure altitude and true altitude be the same?

A

When standard atm conditions exist

66
Q

Where does wind shear exist?

A

At all altitudes in all directions horizontal and vertical.

67
Q

What causes variations in altimeter settings between weather reporting stations?

A

Unequal heating of atmosphere

68
Q
A

Knowledge Test (18 decks)

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