Chapter 10 - Wind Flashcards

1
Q

How is surface wind measured

A

By an Anemometer 10m above the ground

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2
Q

What is calm winds

A

1 knot or less

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3
Q

What is a Lull

A

A sudden drop in wind

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4
Q

What is a Gust

A

Sudden increase in wind 10 knots

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5
Q

gale =

A

43-47 knots

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6
Q

storm =

A

48 - 63 knots

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7
Q

Hurricane =

A

64 +

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8
Q

which north are runways aligned with

A

Magnetic

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9
Q

Squall =

A

An increase of wind that last more than a minute

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10
Q

Met reports use which north

A

True

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11
Q

ATC (ATIS) reports use which north

A

Magnetic

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12
Q

Wind moving clockwise is called

A

Veering

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13
Q

Wind moving anti clockwise is called

A

Backing

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14
Q

If isobars are close together which wind does it indicate?

A

Strong

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15
Q

Wind speed is directly proportional to? It also cause air to move from high to low pressure

A

Pressure Force Gradient

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16
Q

Where in the world is the Coriolis effect least?

A

Equator

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17
Q

Which way does the Coriolis effect deflect in the Northern hemisphere

A

Right

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18
Q

Which way does the Coriolis effect deflect in the Southern hemisphere

A

Left

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19
Q

Increase in Latitude (towards the poles) does what to the Coriolis effect?

A

increases

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20
Q

Geostrophic Wind is

A

When air is moving from H to L and is effected by the Coriolis effect.
The PGF and Coriolis combined when they are equal and opposite to change the wind direction to line up with the straight ISO bars

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21
Q

Gradient Wind is

A

PGF, CF and centrifugal force combine to create curved ISO bars.
Because the centrifugal force is opposing the CF it causes the wind to follow the ISO bars around a depression or high.

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22
Q

Surface Wind is and happens where?

A

In the friction layer (less 1000m) and causes the CF effect to reduce because of the stronger frictional forces near the surface.

23
Q

Surface friction is increase by

A

Thermal activity making turbulent air. Increases with Diurnal Variation / during the daytime

24
Q

Over the sea the Deflection and % of surface speed is

A

10 degrees

70%

25
Q

Over land by day the Deflection and % of surface speed is

A

30 degrees

50%

26
Q

Over land by night the Deflection and % of surface speed is

A

45 degrees

25%

27
Q

In the northern hemisphere when climbing the wind will?

A

Increase and Veer

28
Q

In the northern hemisphere when descending the wind will?

A

Decrease and back

29
Q

On a Low Px what will the wind always do

A

Cut in

30
Q

What is a Sea Breeze

A

Happens on a sunny day with no clouds
the land heats the air and creates a low pressure
the air rises and creates a high and diverse away back to the sea and then sinks again
low px causes a breeze from the sea to the land

31
Q

Where does the sea breeze happen and what wind speed

A

During the day
10-15 NM in land
speed 10 knots

32
Q

How does a land breeze happen and what are the typical figures

A

reverse of sea breeze
5 NM
5 Knots

33
Q

Anabatic Winds happen how

A

Sun heats the surface of a mountain
that heated air then rises up the mountain
creates a low px at the bottom

34
Q

A valley wind is created how and give a typical one

A

From the Anabatic winds leaving Low Px in the valley
By mid afternoon it causes more air to converge to replace the missing air creating winds

Mistral 70 knots

35
Q

Katabatic winds is created how

A

At night the cold mountain side cools the air
Cold air sinking down the mountain
Creates a high pressure

36
Q

Mountain winds at night is created how and give a typical one

A

High pressure is created because of the Katabatic
Diverges the air away

Bora - in winter up to 100 knots

37
Q

Mistral is a valley wind that flows out of

A

Rhone Valley into Med (can reach 70 knots)

38
Q

Foehn Wind is found where

A

In the Alps
Get cloud cap on top of the mountain
on the Lee side will get warm dry air

39
Q

What is Foehn wind called in the Rockies

A

Chinook

40
Q

x3 African winds called Sirocco, Ghibli and Khamsin come from which direction and bring what condition

A

Southerly
Dry, Dusty, Wind and air
Creating a low pressure over the Med

41
Q

Strong winds and uneven surfaces =

A

Mechanical/ frictional turbulence

42
Q

Mountain waves/ standing waves/ Lee waves require x3 things

A

Mountain
15 - 20 knots wind at the top
stable air on the Lee side with unstable air above or below

43
Q

How far downwind can the mountain waves occur

A

50-100NM

44
Q

Give the downwind distances for
Pennines
Rockies
Andes

A

250
300
500

45
Q

Which clouds do you get with mountain waves

A

Cap cloud
Roll / rotor
lenticular

46
Q

Cold Katabatic wind over the Adriatic?

A

Bora

47
Q

x4 examples of Topographic windshear

A

Buildings
Trees
funnelling
mountains

48
Q

Horse latitudes are where

A

Sub tropical highs

49
Q

NE/SE trade winds are from where and heading to

A

subtropical highs and heading to the lows

50
Q

Doldrums (forms at the ITCZ) what are the winds like

A

Calm because the two winds don’t converge right at the surface

51
Q

Westerlies appear where

A

Midlatitude lows

52
Q

Polar easterlies come from

A

The polar highs

53
Q

Harmattan is NE trade wind what condition are usual for it

A

dry
dusty
visibility effected 10-15,000 feet

54
Q

Pampero is what

A

A burst of cold air that crosses the pampas with strong winds oct-jan