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PPL - Meteorology > Winds > Flashcards

Winds Flashcards

1
Q

What are winds caused by

A

PRESSURE GRADIENTS

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2
Q

In the NH

Coriolis force turns the wind ____

A

RIGHT

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3
Q

In the NH

Winds circulate ____ around high pressure system, also known as what type of cyclone

A
  1. CLOCKWISE
  2. ANTI CYCLONE
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4
Q

In the NH

Winds circulate ____ around low pressure system, also known as what type of cyclone

A
  1. ANTI CLOCKWISE
  2. CYCLONE
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5
Q

Wind direction on forecasts is given in TRUE or MAGNETIC north

A

TRUE NORTH

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6
Q

Unit of measurement for wind

A

KNOTS (kt)

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7
Q

Wind reports give teh bearing in the direction the wind is blow TO or FROM

A

FROM

NOT the direction wind is travelling

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8
Q

Runway headings are given in TRUE or MAGENTIC north

A

MAGNETIC

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9
Q

When ATC provide a surface wind, this is given in TRUE or MAGNETIC north

A

MAGNETIC

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10
Q

A sudden, short lived increase in wind speed is known as what

A

GUST

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11
Q

Gusts can be particularly dangerous and affect aircraft in what stage of flight

A

Final stage of approach

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12
Q

What are the wind sock strengths

A

20 kt
25 kt
30 kt
35 kt
40 kt

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13
Q

When will a windsock will be completely horizontal

A

Windspeed reaches the “size” of the windsock

Windsock is 30 kts and wind speed is 30 kts, windsock will be horizontal

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14
Q

What happens to wind speed as altitude increases

A

SPEED INCREASES

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15
Q

At what height is wind considered to be free of surfce influences

A

2000 ft

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16
Q

What causes wind to slow down closer to the surface layer

A

FRICTION

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17
Q

Over land, wind speed at the surface is ____% of wind speed at ____ ft

A
  1. 50%
  2. 2000 ft
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18
Q

Over sea, wind speed at the surface is ____ % of wind speed at ____ ft

A
  1. 80%
  2. 2000 ft
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19
Q

In the NH

The wind BACKS or VEERS towards the surface

A

BACKS DOWN

Wind bearing at 2000 ft = 270॰/20kt
Wind bearing at surface = 240॰/10kt
Wind BACKED DOWN i.e. from 270 to 240
Air speed over land decreased closer to the surface by 50%

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20
Q

In the NH

Over land, wind will BACK or VEER by ____ % at the surface

A
  1. BACK
  2. 30-40%

REVIEW HERE
Side of Right hand DOWN on table, bent BACK at wrist
Side of Left hand placed ON TOP of right hand bent forward (appears like a cross)
Finger tips or wrists represent where air flow is coming FROM
From upper hand to lower hand, it is now seen that the wind is backing down

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21
Q

In the NH

Over sea, wind will BACK or VEER by ____ % at the surface

A
  1. BACK
  2. 10%

REVIEW HERE
Side of Right hand DOWN on table, bent BACK at wrist
Side of Left hand placed ON TOP of right hand bent forward (appears like a cross)
Finger tips or wrists represent where air flow is coming FROM
From upper hand to lower hand, it is now seen that the wind is backing down

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22
Q

Sea/Land breeze

During the day, wind will flow in which direction

A

SEA to LAND

23
Q

Sea/Land breeze

During the night, wind will flow in which direction

A

LAND to SEA

24
Q

What is the Diurnal Effect

A

Difference between night and day
Wind variations resulting from suns heating effect on earth during the day

25
Q

Diurnal effect

During the day, winds at surface level are WEAKER or STRONGER
Why

A
  1. STRONGER
  2. More mixing of air at surface with upper winds

Sun heats the land causing convention currents (rising air)

26
Q

Winds at surface level are stronger at DAY or NIGHT

A

STRONGER in DAY

Sun heats the land causing convention currents (rising air)
Bigger difference between high and low pressures, air moves from high to low hence stronger winds

27
Q
  1. An INCREASE in wind bearing is known as ____
  2. A DECREASE in wind bearing is known as ____
A
  1. VEERING
  2. BACKING
28
Q

Stronger winds at the surface during the day VEER or BACK compared to the winds aloft

A

VEER

Stronger winds overcome friction with the surface, so align more with winds aloft
Coriolis force more dominant

29
Q

Coriolis force is more dominant with winds at the surface under what conditions and why

A
  1. During the day
  2. When there are strong winds
  3. Overcome surface friction
30
Q

What happens to air in contact with the ground at night

A

COOLS

Convection does not take place

31
Q

Why is there less strong surface wind at night than during the day

A

Air is cooled so less (or no) convection
Less mixing with air aloft

32
Q

At night, Corilois force is STRONGER or WEAKER than during the day

A

WEAKER

Less mixing with stronger wind
Earth friction is stronger so more dominant than Coriolis

33
Q

Cool dense air descending down the hill surface is known as what

A

KATABATIC WIND

34
Q

Why does cool air descend down the hill face

A
  1. Cooled
  2. More Dense, making it heavier
  3. Gravity
35
Q

What causes Anabatic wind

A

SURFACE HEATING DURING THE DAY

Hill surface heats up during the day
Layer of air above surface is heated - Hot air rises

36
Q

Why are anabatic winds typically weaker than katabatic winds

A

Katabatic
Dense heavy air. Working with gravity sliding down hill
Anabatic
Less dense, hot rising air. Working against gravity

37
Q

What does a greater pressure differential between high and low systems cause

A

STRONGER WINDS

38
Q

Tightly packed isobars causes what?

A

STRONG WINDS

39
Q

Light packed isobars causes what?

A

LIGHT WINDS

40
Q

Do not taxi or take off if wind speed is ____ % of ____

A

50%
STALL SPEED

41
Q

Stronger wind means ____ turblance at ____ level

A

GREATER
LOW

42
Q

Where can a pilot find the “rough air” speeds

A

PILOTS OPERATING HANDBOOK
(POH)

43
Q

How is maxmimum speed in rough (turblent) air indicated on the ASI

A

Vno

Velocity - Normal operating range

44
Q

When does turbulence typically reduced
Why

A

AT NIGHT
LESS MIXING OF AIR BY NIGHT

45
Q

Turbulence caused by landmarks such as buildings or trees is known as what

A

OBSTRUCTIONAL TURBULENCE

46
Q

What are the 4 categories of turbulence

A
  1. LIGHT
  2. MODERATE
  3. SEVERE
  4. EXTREME
47
Q

What is the defintion of wind shear

A

Change in strength or direction of wind

48
Q

Wind shear is most dangerous when?

A

FINAL STAGES OF APPROACH

49
Q

What is a microburst
Where are they found

A

Highly dangerous downdraft
Localised geographically within 4km

50
Q

Flying towards a microbust outflow causes an INCREASE or DECREASE in rate of descent

A

DECREASE

Head wind dominant, lift increased
LINK HERE

51
Q

Flying away from a microburst outflow cuases an INCREASE or DECREASE in rate of descent

A

INCREASE

Tail wind dominant, less air flow over wings, lift reduced
LINK HERE

52
Q

What are 2 possible benefits from a change in altitude to take advantage of a change in wind direction

A
  1. Fuel conservation
  2. Reduced route time
53
Q

In turbulence, what are 2 things a pilot should never do

A
  1. Use abrupt full control deflection
  2. Exceed Vno

PPL - Meteorology (17 decks)

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