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CFI > Weather > Flashcards

Weather Flashcards

1
Q

Characteristics of stable air

A

Stratiform clouds

Smooth turbulence

Steady precipitation

Fair to poor visibility

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2
Q

Characteristics of unstable air

A

Cumuliform clouds

Rough turbulence

Showery precipitation

Good visibility

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3
Q

Low pressure system

A

Rising air

Conducive to cloudiness, precipitation and bad weather

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4
Q

High pressure system

A

Descending air

Dissipation of clouds

Good weather

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5
Q

Cold front

A

Occurs when a mass of cold, dense, and stable air advances and replaces a body of warmer air.

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6
Q

Occluded front

A

A fast moving cold front catches up to a slow moving warm front.

The warm front rises above

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7
Q

Warm front

A

The boundary area formed when a warm air mass contacts and flows over a colder air mass

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8
Q

Stationary front

A

Forces of two fronts are relatively equal. Mixture of warm and cold fronts, can influence local weather for a few days

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9
Q

What is dew point?

A

Dew point is the temperature to which air must be cooled to reach saturation

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10
Q

Characteristics of a cold front

A

Towering cumulus or cumulonimbus clouds

Heavy rain and lightning

Thunder or hail - tornadoes possible

Poor vis

Winds variable and gusting

Temp/dew point, barometric pressure drop rapidly

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11
Q

Characteristics of a warm front

A

Stratiform clouds

Drizzle

Low clouds and poor visibility

Variable winds

Rise in temperature

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12
Q

What is a trough?

A

Elongated area of low pressure

Orange on wx chart

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13
Q

What’s a ridge?

A

Elongated area of high pressure

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14
Q

What is a microburst?

A

Small scale intense downdrafts which spreads outward in all directions when it reaches the surface.

Can be found almost anywhere there is convective activity

Less than 1 mile in diameter as it descends from the cloud base

As strong as 6,000fpm

Can extend 2.5 miles near ground level

Seldom last longer than 15 minutes

Can result in wind shear

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15
Q

What is wind shear?

A

Sudden change of wind velocity and direction

Most often caused by microbursts, temp inversions, and surface obstructions

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16
Q

How far should you avoid a thunderstorm?

A

20 miles or greater.

You can encounter hail and violent turbulence within 20 miles of a strong storm

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17
Q

Convective SIGMET

A

Issued hourly at 55 minutes past the hour. Valid for 2 hours

Severe T storms
Surface winds greater or equal to 50kts
Hail at surface greater than 3/4 inch

Tornadoes
Embedded t storms
Always implies severe or greater turbulence, severe icing, or wind shear

18
Q

SIGMET

A

Max forecast of 4 hours

Non convective activity
Severe icing not associated with t storms
Clear air turbulence
Dust storms, sand storms leaving vis below 3 miles
Volcanic ash

19
Q

AIRMET

A

Can affect all aircraft but but potentially hazardous to to aircraft with limited ability

Valid for 6 hours

Tango - turbulence, sustained surface winds of 30kts or greater. Low level wind shear

Sierra - IFR conditions or mountain obscurations

Zulu - icing and provides freezing level heights

20
Q

PIREP (UA)

Urgent PIREP (UUA)

A

Pilot weather reports

21
Q

METAR

A

Surface weather observations.

Scheduled METAR’s published every hour

Non scheduled (SPECI) are issued when there is one of more significant change in previous METAR

22
Q

TAF

A

Terminal Aerodrome Forecast

Forecast for 5sm around the station.

Issued 4 times a day every 6 hours and normally cover a 24-30 hour period

23
Q

Standard day

A

15 Celsius

29.92

24
Q

What is the standard lapse rate?

A

2 degrees Celsius per thousand feet

25
Q

Conditions necessary for formation of thunderstorm:

A

Sufficient water vapor (humidity)

An unstable temperature lapse rate

Uplifting action

26
Q

Life cycle of a thunderstorm

A

Cumulus stage - lifting action, storm starts to grow

Mature stage - precipitation falls from cloud base. Updrafts and downdrafts

Dissipating stage - strong downdrafts and cell is dying rapidly

27
Q

What is fog?

A

A cloud that begins within 50 feet of the surface.

It occurs when the air temperature near the ground reaches its dew point, or when the dew point is raised to the existing temperature by added moisture to the air.

28
Q

What are the types of fog?

A

Radiation

Advection

Ice

Steam

Upslope

29
Q

Radiation fog

A

Occurs at calm clear nights when the ground cools rapidly due to the release of ground radiation

30
Q

Advection fog

A

Warm, moist air moves over a cold surface.

Winds are required for advection fog to form.

31
Q

Ice fog

A

Forms when temp is much below freezing and water vapor turns directly into ice crystals

32
Q

Upslope fog

A

Moist, stable air is forced up a terrain slope and cooled down to its dew point by adiabatic cooling.

33
Q

Steam fog

A

Cold, dry air moves over warm water. Moisture is added to the air mass and steam fog forms

34
Q

Structural ice

A

Two conditions for formation

Visible moisture (clouds, fog, precipitation)

Aircraft surface temperature below freezing

35
Q

Clear ice

A

Most dangerous. Heavy, hard and difficult to move.

Caused by large supercooled water droplets near freezing point

Freezes as smooth sheet of ice

36
Q

Rime ice

A

Opaque, white, rough ice, formed by small supercooled water droplets freezing quickly

Occurs at lower temps than clear ice

37
Q

Mixed ice

A

Clear and rime formed simultaneously

38
Q

Instrument ice

A

Structural ice forming over aircraft instrument and sensors

Pitot and static

39
Q

Induction ice

A

Ice reducing the amount of air for the engine intake.

Intake ice - blocks engine intake

Carburetor ice - may form due to steep temp drop and carburetor Venturi

40
Q

How do you get carburetor icing?

A

Caused by temperature drop in the carburetor, as an effect of fuel vaporization, and the temperature drop associated with the pressure drop in the Venturi.

Temps between 20-70 Fahrenheit are most conducive to carb icing

41
Q

What is frost?

A

Ice crystals caused by sublimation when both the temperature and dew point are below freezing.

Degrades aircraft performance by 30-40%

CFI (18 decks)

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