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ATPL Meteorology > Wind > Flashcards

Wind Flashcards

(80 cards)

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1
Q

How do you measure surface wind

A

Anemometer

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2
Q

How high is a anemometer placed

A

10m agl (33ft)

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3
Q

What is a gust

A

Wind increases by 10 kts for less than a minute

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4
Q

What is calm wind

A

<1knot

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5
Q

What is a gale

A

34-47kt

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6
Q

What is a storm

A

48-63 knots

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7
Q

What is a hurricane

A

> 64 kts

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8
Q

What is a squall wind

A

Gust lasting more than 1 minute

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9
Q

What is a lull

A

Sudden drop in wind speed

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10
Q

What North is used for wind direction from ATC / ARIS

A

Magnetic

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11
Q

What North is used for all meteorological reports in wind

A

True

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12
Q

When does a geostrophic wind occur

A

When pressure gradient and Coriolis force equal in strength and magnitude in opposite directions

Straight isobars

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13
Q

What is the gradient wind model

A

The same as the geostrophic wind except that it takes into account of turning air flow

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14
Q

What happens to a sea/ land breeze in the northern hemisphere

A

Deflected to the right due to Coriolis

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15
Q

What height do sea breezes affect

A

Up to around 1000ft

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16
Q

What causes adiabatic winds

A

Daytime

Side of mountain heats up due to sun

Air next to it heats up

Less dense

Rises

Upwards wind

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17
Q

What is a katabatibc wind

A

Nighttime

Opposite of adiabatic

Can cause a mountain wind which is air flowing out of a valley into an assumed plain (dependant on land)

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18
Q

What is the bora

A

A katabatic wind near Italy

Strongest in winter when air is coolest

Speeds of up to 100kts

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19
Q

What is the mistral

A

Wind flows down the Rhône valley between the alps and the mistral into the Mediterranean

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20
Q

What are the southerly winds from North Africa called

A

Sirocco
Ghibli
Khamsin

Dry dusty winds

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21
Q

What are isohypes

A

Lines of equal height set at a certain pressure

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22
Q

What is the speed of a jet stream

A

Over 60 knots

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23
Q

What do close isohypes represent

A

Likely to be jet stream

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24
Q

Where is the maximum clear air turbulence at a jet stream

A

Primary CAT = in warm air mass on the cold air side of the core, level with or just below the core

Pad pilot p312

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25
Where is the secondary CAT for a jet stream
Above the core at the tropopause
26
What is a isotach
Lines of equal windspeed
27
What is the average jet steam dimensions
2nm deep 2000nm long 200nm wide
28
What is the depth - width ratio of a jet stream
1:100
29
What is the depth - length ratio of a jet stream
1:1000
30
What season are jet streams strongest
Winter
31
What causes jet streams
Temperature difference
32
“As climbing towards the jet stream” what happens to the wind direction
Veers
33
If you take off at the warm front and fly to the tropopause / jet stream what direction does the wind change
Veers
34
If you take off st the cold front and fly towards the jet stream what way does the wind go
Backs
35
If you’re at the surface when a front passes what happens to the wind
Veers
36
What happens to wind speed near s trough or s ridge
Wind speed faster
37
How fast does a jet stream need to be to appear on a sigwx chart
> 80 knots
38
What speed is the vertical extent of a jet stream shown
>120 knots
39
What does a double bar at a jet stream mean
Speed change of more than 20 knots Or height change of more than 3000 ft
40
Where is the arctic jet stream
60°n
41
When and what height and speed is the arctic jet stream
Winter only in northern hemisphere 20,000 ft (400hpa) 80 knots
42
Where is the polar jet stream
Winter = 40-60°n > s/w Uk Summer 70°n novascotia > Scottish islands)
43
What height and speed is the polar front jet stream
30,000 feet (300hpa) 200knots average Stronger in winter Fastest jet stream
44
What can clear air turbulence cause
Structural damage Fatigue
45
Where and when is the sun tropical jet stream
Winter = 20°n Summer = 40°n All year round
46
What height and speed is the sub tropical jet stream
40,000feet 100knots Stronger in winter
47
Where is the equatorial jet stream (tropical easterly jet stream)
10-20°n Only jet stream to go east Around India / east Africa When land masses have heated more than the sea below
48
How High / fast is the equatorial jet stream
50,000 ft 70-100 knots
49
What jet streams exist in the Southern Hemisphere
Only the sub tropical and polar jet streams
50
Where do you find low level jet streams
Southern Germany Kansas
51
What causes low level jet streams
Cold air mass / warm air mass boundary 500> 5000 feet Usually around 70 knots
52
Does the temperature change in the core of a jet stream if you fly through it
Nope
53
What clouds are associated with jet streams
Cirrus
54
Where is the biggest temperature different founded for jet stream formation
Between polar and tropical air
55
How deep is the friction layer
2/3000 ft
56
What does the wind do in the friction layer over land during the day
Speed halves Backs by around 30° during the day over land
57
What does wind do in the friction layer over the sea
Slowed by 25% | Backs by 10°
58
At night what happens to the height of the friction layer over land
Due to less thermal heating = shallowed 1/1500 feet
59
At night what happens to the friction layer over land
Speed reduces by 75% Wind direction backs by 45°
60
What are foehn clouds
Where warm moist air blows on the windward side of a mountain Rises condenses cools at a slower rate Rain falls making the air dry Stable so falls on other side of mountain Becomes unsaturated sooner Therefor warms quicker making it warmer on leeward side
61
What is the foehn called over the Rocky Mountains
Chinook
62
What is the foehn caked over the Andes
Santa Anna
63
What are the winds at the 40°s 50°s Called
Roaring 40s Furious 50s Very fast westerly winds
64
What is a equatorial doldrums
Very light wind at itcz
65
What are the North easterly winds over North Africa called
Harmattan Bad vis
66
What is the pampero
Local winds of South America burst of cold polar air from south west in South America Strongest every summer Associated with cold front Happens in s Australia
67
After what height does the turbulence criteria include in transport aircraft
>15,000 feet
68
What is light turbulence
Bit bumpy but not much May feel flight strain on seatbelts Can still walk / serve food 5-15kt fluctuations in IAS If no airspeed change = light chop
69
What is moderate turbulence
``` Bumps jolts Positive control of aircraft at all times 15-25knot speed fluctuations Definite strain on seatbelts Insecure objects dislodged Struggle to walk / serve food ```
70
What is severe turbulence
Momentary loss of control IAS fluctuations 25> Food / walking impossible Insecure objects tossed about
71
When should you report turbulence
If not already been reported moderate / severe and above 15,000ft
72
What is occasional turbulence
Less than 1/3 of the time
73
What is intermittent turbulence
1/3 > 2/3 of the time
74
What is continuous turbulence
More than 2/3 of the time
75
What causes mountain waves
Wind flowing >15 knots at top of mountain 90° (+/-30) to mountain Layer of stable air on top of mountain with less stable air above and below
76
What area causes the greatest danger in mountain waves
Rotor zone
77
How far can mountain waves affect after mountain s
50-100nm
78
How fast can the up/down draughs be for mountain waves
1000feet/min
79
What is the scale for wondshear
Horizontal = knots / 1000ft Vertical = knots / 100ft
80
Where can wind shear occur
At top of inversions In micro bursts CB/TS frontal passage

ATPL Meteorology (8 decks)

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