Wind

Question 1

What measures surface wind

Answer 1

Anemometer

, 10m or 30ft agl

Question 2

Gust

Answer 2

Sudden change in wind speed by 10kts in less than a min

Question 3

Calm

Answer 3

1kt or less

Question 4

Gale force

Answer 4

34-47kts

Question 5

Storm force

Answer 5

48 - 63kts

Question 6

Hurricane force

Answer 6

Greater than or equal to 64

Question 7

Squall

Answer 7

Gust lasting more than 1 min

Question 8

Lull

Answer 8

Sudden drop in wind speed

Question 9

What happens to the surface wind in the northern hemisphere

Answer 9

Backed and slacks

Question 10

Sea breeze wind speed

Answer 10

10 - 5kts

Question 11

Anabatic

Answer 11

Winds going up the mountain, low pressure which is caused by convection, air comes in and goes up the mountain

Question 12

Katabatic wind

Answer 12

Typical at night, surface cools, get denser, falls down the mountain

Question 13

Geostrophic wind

Answer 13

The CF and PGF are equal and opposite and the wind gets deflected 90 degrees so wind travels parallel to the isobars

Question 14

Ballots law

Answer 14

Back to the wind, low pressure will be on your left

Question 15

Gradient wind

Answer 15

Wind coming out a high/low pressure

Coming out a high due to centrifugal for acting in the same direction, the the wind is faster

Wind around a low is slower due to the centrifugal force and the corolis acting the opposite direction

Question 16

Deflection of the wind over the sea and % of the 3000ft wind

Answer 16

10 degrees, 70%

Question 17

Deflection of the wind over the land by day and % of the 3000ft wind

Answer 17

30 degrees, 50%

Question 18

Deflection of the wind over the land by night and % of the 3000ft wind

Answer 18

45 degrees, 25 %

Question 19

Diurnal variation

Answer 19

Durning the day, thermal activity on the surface causes fast high level air to get mixed with slow surface air to get a faster overall wind speed

Durning the night, less thermal air, no rising air, less mixing

Question 20

Sea breeze formation

Answer 20

Surface heating on the land causes a low pressure to form and thus causing a PGF, goes in opposite direction in the night

Wind gets deflected due to the CF

About 5 - 10kts, faster the speed, bigger the deflection

Question 21

Land breeze

Answer 21

Opposite to sea breeze

Question 22

Katabatic wind

Answer 22

Typical at night, surface cools, gets denser and falls down the mountain

Question 23

Example of the katabatic effect

Answer 23

The Bora, effects the adratic sea

Question 24

Example of valley winds

Answer 24

High pressure in the north Western Europe to low pressure in the south
PGF goes through the alps causing a Venturi
Strong relatively cold and dry wind

Question 25

Foehn wind

Answer 25

Stable, saturated air gets pushed up a mountain, cools, forms cap cloud, rains, dries, comes down the mountain as the DALR and is warmer

Question 26

Examples of foehn wind

Answer 26

Alps

Chinook in the rockies

Question 27

What happens in the med in winter

Answer 27

The low pressure over the med sea, drags the dry air from n Africa up

This mixes with the cold air from the European land mass and can cause intense storms

Question 28

Strong winds in the Southern Hemisphere

Answer 28

Roaring 40s
Furious 50s
Screaming 60s

Question 29

Doldrums

Answer 29

Calm surface conditions due to surface convergence at the ITCZ

Question 30

Harmattan

Answer 30

NE trade winds over w Africa

Dry sands can impact visibility

Strongest in jan due to the ITCZ moving downwards
Reduces viz up to 3000ft
Can extend to 10-15,000ft

Question 31

Pampero

Answer 31

S America

Cold polar air moves the flat land, increasing wind speed

Strongest winds occur early summer