050.02 Wind

Question 1

The pressure gradient force acts (parallel/perpendicular) to the isobars towards the (lower/higher)​ pressure.

Answer 1

The pressure gradient force acts (perpendicular) to the isobars towards the (lower) pressure.

Question 2

Surface wind is measured (2 / 8-10)​ m above the ground on a mast with an anemometer.

Answer 2

Surface wind is measured (8-10) m above the ground on a mast with an anemometer.

Question 3

Cold depressions become (stronger/weaker)​ with height.

Answer 3

Cold depressions become (stronger) with height.

Question 4

The average height of the jet core within a sub-tropical jet stream is (…)​ ft.

Answer 4

The average height of the jet core within a sub-tropica jet stream is (40 000) ft.

Question 5

Conditions most favourable to the formation of mountain waves are (stable/unstable) air, wind speed (below/above) 20 kts blowing (across/parallel) the ridge.

Answer 5

Conditions most favourable to the formation of mountain waves are (stable) air, wind speed (above) 20 kts blowing (across) the ridge.

Question 6

Minimum speed for a wind to be classified as a jet stream is (…) ​kts.

Answer 6

Minimum speed for a wind to be classified as a jet stream is (60) kts.

Question 7

In the Northern Hemisphere, the Coriolis force deflects the wind to the (left/right)​. Coriolis force is (zero/maximum)​ at the equator.

Answer 7

In the Northern Hemisphere, the Coriolis force deflects the wind to the (right). Coriolis force is (zero) at the equator.

Question 8

The two jetstreams that exists all year around are the (…) jet and the (…) jet.

Answer 8

The two jetstreams that exists all year around are the (polar front) jet and the (sub-tropical) ​jet.

Question 9

Divergence in the upper air that is greater than the convergence in the friction layer results, near the surface, in (rising/falling) pressure and likely (formation/dissipation) ​of cloud.

Answer 9

Divergence in the upper air that is greater than the convergence in the friction layer results, near the surface, in (falling) pressure and likely (formation) of cloud.

Question 10

State the two seasonal jetstreams, their direction, the season they occur and their approximate latitude.

Answer 10

State the two seasonal jetstreams, their direction, the season they occur and their approximate latitude:

• Arctic jet; westerly; occurs in winter months; around 60°N
• Equatorial jet; easterly; occurs during summer months; around 15°N

Question 11

The average height of the jet core within a polar front jet stream is (…)​ ft.

Answer 11

The average height of the jet core within a polar front jet stream is (30 000) ft.

Question 12

Geostrophic force is strongest close to the (equator/poles)​.

Answer 12

Geostrophic force is strongest close to the (poles).

Question 13

The wind, which blows when pressure gradient and coriolis forces are in balance is the (…)​ wind.

Answer 13

The wind, which blows when pressure gradient and coriolis forces are in balance is the (Geostrophic) wind.

Question 14

The worst area for CAT in the vicinity of the polar jet stream is normally located (in/above/below) the core on the (tropical/depression)​ side.

Answer 14

The worst area for CAT in the vicinity of the polar jet stream is normally located (below) the core on the (depression) side.

Question 15

The average height of the jet core within an arctic jet stream is (…)​ ft.

Answer 15

The average height of the jet core within an arctic front jet stream is (20 000) ft.

Question 16

Wind that has changed anti-clockwise in direction can be said to have (backed/veered)​.

Answer 16

Wind that has changed anti-clockwise in direction can be said to have (backed).

Question 17

Using a cup anemometer, (…) ​can be measured.

Answer 17

Using a cup anemometer, (wind speed) can be measured.

Question 18

Warm depressions become (stronger/weaker)​ with height.

Answer 18

Warm depressions become (weaker) with height.

Question 19

Warm anti-cyclones become (stronger/weaker)​ with height.

Answer 19

Warm anti-cyclones become (stronger) with height.

Question 20

On the Northern hemisphere over sea, surface winds are (backing/veering) by about (…)° and speed slows down to about (…)​% of the 2000 ft geostrophic winds.

Answer 20

On the Northern hemisphere over sea, surface winds are (backing) by about (10)° and speed slows down to about (70)% of the 2000 ft geostrophic winds.

Question 21

The approximate ratio between the height and widt for a jetstream cross section is in the range of 1:(1/10/100/1000)​.

Answer 21

The approximate ratio between the height and widt for a jetstream cross section is in the range of 1:(100).

Question 22

Turbulence caused by the friction of air flowing over the earth’s surface is (…) ​turbulence.

Answer 22

Turbulence caused by the friction of air flowing over the earth’s surface is (mechanical) turbulence.

Question 23

In the Northern hemisphere, the winds flow clockwise around a (LOW/HIGH) pressure area, (cyclonic/anti-cyclonic) flow.

Answer 23

In the Northern hemisphere, the winds flow clockwise around a (HIGH) pressure area, (anti-cyclonic) flow.

Question 24

A cloud type frequently associated with jet streams is a (…) cloud band on the (equatorial/polar)​ side of the jet stream.

Answer 24

A cloud type frequently associated with jet streams is a (CI) cloud band on the (equatorial) side of the jet stream.

Question 25

State the main explanation for the faster wind speeds at upper levels.

Answer 25

A lower density of the air.

Question 26

The greater the horizontal pressure gradient, the (closer/further apart) the isobars and the (stronger/weaker)​ the wind.

Answer 26

The greater the horizontal pressure gradient, the (closer) the isobars and the (stronger) the wind.

Question 27

Wind that has changed clockwise in direction can be said to have (backed/veered)​.

Answer 27

Wind that has changed clockwise in direction can be said to have (veered).

Question 28

In summer in the northern hemisphere, the maximum wind speeds associated with sub-tropical jet streams are usually located (below/above) the tropopause at about (100/200/250/300) ​hPa.

Answer 28

In summer in the northern hemisphere, the maximum wind speeds associated with sub-tropical jet streams are usually located (below) the tropopause at about (200) hPa ≈ 40.000 ft.

Question 29

Polar front jet streams over the South Pacific are usually strongest in (January/July)​.

Answer 29

Polar front jet streams over the South Pacific are usually strongest in (July).

- Strongest in Winter, which is in July on SH -

Question 30

Gradient wind speed (increases/decreases) with increasing latitude.

Answer 30

Gradient wind speed (decreases) with increasing latitude.

Question 31

On the Northern hemisphere over land, surface winds are (backing/veering) by about (…)° and speed slows down to about (…)​% of the 2000 ft geostrophic winds.

Answer 31

On the Northern hemisphere over land, surface winds are (backing) by about (30)° and speed slows down to about (50)% of the 2000 ft geostrophic winds.

Question 32

Cold anti-cyclones become (stronger/weaker)​ with height.

Answer 32

Cold anti-cyclones become (weaker) with height.