Wind

Question 1

How is Pressure Gradient Wind calculated

Answer 1

PGF=dp÷(dn x p)
Where: dp=pressure diff between 2 points
dn=horizontal distance between 2 points
p=air density

Question 2

What is Coriolis/Geostrophic Force

Answer 2

Deflection of air (to the right in NH and to the left in SH) of air moving towards the poles

Question 3

How do you calculate the magnitude of CF

Answer 3

CF=2ΩPVsinθ
Where:Ω=angular rotation of earth
P=air density
V=wind speed
θ=latitude

Question 4

What is Geostrophic Wind

Answer 4

When PGF and CF balance each other out, the resulting wind, blowing parallel to straight isobars, is Geostrophic

Question 5

What is Centripetal Acceleration

Answer 5

CA creates a force directed at right angles to the flow of wind and inwards towards the centre of rotation, producing a circular pattern of flow around centres of HP and LP

Question 6

For CF, CA and PGF to be in equilibrium, must the CF be greater than or less than the PGF

Answer 6

Greater than

Question 7

What is Buys Ballot’s Law

Answer 7

Observer who stands with his back to the wind in the SH, the LP would be to his right

Question 8

1-What is the difference between Veering and Backing
2-does wind veer/back with an increase in alt, and does the wind speed increase/decrease (SH)

Answer 8

1-Veer:wind changes in clockwise direction
Back:wind changes in anticlockwise direction
2-backs and increases due to surface friction

Question 9

1-What is a sea breeze
2-What is a land breeze

Answer 9

1-Wind blowing from sea to land
2-Wind blowing from land to sea

Question 10

What causes valley (anabatic) wind
Which side of the mountain is it most likely to occur (N, S, E, W)

Answer 10

Heating of mountain slope during the day
Westward side

Question 11

What causes Mountain(katabatic) wind
What is likely to happen at the bottom of the valley

Answer 11

At night when air cools down, air becomes more dense and slides down slope of mountain
Fog/mist is likely to build due to collection of cold air

Question 12

What is Föhn wind

Answer 12

Warm, dry air blowing on leeward(downward) side of mountain

Question 13

What is a Berg wind
What season does it usually occur in

Answer 13

Hot, dry wind that blows from interior of SA to coast, usually blustery
Usually during winter

Question 14

What are Mountain Waves

Answer 14

Air flowing accross mountain range, once over top it pours down the other side with considerable force, creating Eddie’s and turbulence

Question 15

What causes Cap Clouds

Answer 15

Orographic uplift, causing cloud to form on top of ridge

Question 16

What can be expected near Lenticular Clouds

Answer 16

Mountain Waves

Question 17

How are Rotor clouds formed

Answer 17

Formed in Rolling Eddie’s

Question 18

What happens to indicated Altitude with an increase in wind speed

Answer 18

Shows a increase in alt, due to a decrease in pressure

Question 19

What are 4 common sources for Wind Shear

Answer 19

1-Thunderstorms
2-Fronts
3-Temp Inversions
4-Mechanical Turbulence

Question 20

1-Where are Dust Devils most likely to occur
2-What type of pressure system are they
3-How are they formed

Answer 20

1-hot,dry plains
2-LP
3-with a Steep Lapse Rate, caused by cool air over a hot surface

Question 21

What is the Subtropical HP zone produced by

Answer 21

Vertically descending air currents from the Hadley Cell

Question 22

1-What direction do trade winds blow in the NH
2-What are they called
3-What direction do trade winds blow in the SH
4-What are they called

Answer 22

1-From NE to SW
2-NE Trades
3-From SE to NW
4-SE Trades

Question 23

What is the Sirocco and where does it occur

Answer 23

Hot dry SE to SW wind, originating as hot air over North Africa, blowing N into Southern Mediterranean basin

Question 24

What is the Kamsin and where does it occur

Answer 24

Hot, dry and dusty S/SE wind occurring in North Africa around the East Mediterranean

Question 25

What is the Mistral and where does it occur

Answer 25

Valley wind blowing from S of France to French Mediterranean coast
Northerly cold during winter and early spring

Question 26

What is the Bora and where does it occur

Answer 26

NE wind and of gale force, strongest and most frequent during winter
Blows down North Adriatic with HP over central Europe and LP over Adriatic Sea

Question 27

What is the Simoon and where does it occur

Answer 27

Hot, dry, dusty wind that moves accross African deserts

Question 28

What is the Shamal and where does it occur

Answer 28

N-NW wind blowing over Iraq and Persian Gulf States

Question 29

What is the Haboob and where does it occur

Answer 29

Strong sand/dust storm occurring along Southern edges of Sahara
Dust storm followed by torrential rain
Wind direction N in winter, E-S in summer

Question 30

What is the Harmattan and where does it occur

Answer 30

Dry, dusty West African trade wind, dependant on pos of ITCZ
Blows from Sahara into Gulf of Guinea

Question 31

What is a Jet Stream

Answer 31

Ribbons of very strong winds which move the weather systems around the globe, transporting high and lows, mark boundaries between air masses, usually sit at tropopause

Question 32

How are Jet Streams caused

Answer 32

Caused by temp difference between tropical and polar air masses

Question 33

1-Which direction does the Polar Front Jet move
2-Where is it the strongest
3-Is the cyclonic side cold/warm, and does it have stronger/weaker wind shear than the anti-cyclonic side
4-where is it formed
5-does it move N/S during summer

Answer 33

1-W to E - Westerly
2-between Troughs and Ridges
3-cold, has stronger wind shear
4-formed on boundary between cold polar air and warm sub tropical air
5-moves N

Question 34

In the NH with the PFJ:
1-is there a temp change when flying through the Polar Front Jet Core Height
2-above the zero layer, what happens to the temp gradient, the pressure gradient and the wind speed
3-when flying below the jet core height, what happens to the temp in a N/S direction
4-when flying in a S to N direction, with a Westerly crosswind from the left, and a decrease in temp at alt, must the A/C fly above/below the jet stream and why
5-when flying from N to S with a crosswind from the right and an increase in temp with alt, must the A/C fly above/below the jet stream and why

Answer 34

1-no.
2-temp gradient:reverses, pressure gradient:decreases, wind speed:decreases
3-there is an increase in temp, colder air to the left(N) and warmer air to the right(S)
4-Below the Jet Stream, because the wind speed will increase
5-below the Jet Stream, wind will increase with alt

Question 35

1-how does the Sub-Tropical Jet form
2-in the NH does the Geostrophic force deflect left/right when moving W to E

Answer 35

1-Forms over sub-tropical anticyclones when air from the Hadley and Ferrel cells meet
2-right

Question 36

1-Which direction does the Equatorial Jet Stream move
2-which side is there more turbulence
3-is it found in the NH or SH

Answer 36

1-E to W
2-on cyclonal(S) side
3-NH

Question 37

1-how is thermal wind caused
2-how does the CF affect the flow of air in the NH and SH
3-which direction does the resultant air flow in regards to isotherms(areas of equal temp)

Answer 37

1-caused by pressure gradient trying to move air from HP, H temp to LP, LT at any alt
2-deflected right in NH and left in SH
3-flows parallel to isotherms

Question 38

1-what is Clear Air Turbulence
2-how is it caused
3-do the mainly occur on cold/warm sides of jet streams in the NH

Answer 38

1-turbulence not associated with clouds, not able to be detected visually
2-caused by vertical and horizontal wind shears together with strong horizontal temp fluctuations
3-cold