Atmospheric Circulation and Wind

Question 1

What is the idea behind general circulation?

Answer 1

• More direct sunlight at equator causes greater warming and rising of air, replaced by cooler air further from the equator.
• Results in a general circulation pattern.

Question 2

What are the 3 cells in the 3 Cell Model of global circulation?

Answer 2

1. Polar Cell
2. Mid Latitude Cell
3. Tropical Cell

Question 3

What causes the formation of the 3 cells?

Answer 3

Coriolis force

Question 4

What direction does the Coriolis force tend to deflect particles in the Southern Hemisphere? What about Northern Hemisphere?

Answer 4

• To the left in SH

- To the right in NH

Question 5

What is the Coriolis force an apparent force?

Answer 5

Because the deflection is relative to the observer not relative to the particle’s movement through space

Question 6

What causes the Coriolis force?

Answer 6

Rotation of the earth.

Question 7

What is Coriolis force proportional to?

Answer 7

1. Wind Speed

2. Latitude (zero at the equator, maximum at the poles).

Question 8

What is the pressure gradient force?

Answer 8

Movement of air from HP to LP

Question 9

On a synoptic chart, what do isobars being close together mean?

Answer 9

Represent a large change in pressure over a small distance

• Pressure difference will be high
• PGF will be high
• Speed of the wind will be high

Question 10

On a synoptic chart, what do isobars far apart mean?

Answer 10

Small change in pressure over a large distance

• The PGF will be low
• The Wind speed will also be low

Question 11

What direction do winds flow on an synoptic chart?

Answer 11

Parallel to isobars

Question 12

What is geostrophic wind?

Answer 12

Balanced flow between Coriolis force and pressure gradient force
- Flow will be parallel to the isobars.

Question 13

What causes the predicted geostrophic flow away from being parallel to the isobars slightly at the surface?

Answer 13

Friction

Question 14

What direction does air flow around an area of high pressure in the southern hemisphere?

Answer 14

Anti-clockwise

Question 15

What direction does air flow around an area of low pressure in the southern hemisphere?

Answer 15

Clockwise

Question 16

What are the 2 main jet streams and where do they occur?

Answer 16

1. Subtropical Jet - forms near the boundary of the Tropical and Mid Latitude circulation cells
2. Polar Jet - Forms near the boundary of the Polar Cell and Mid Latitude Cell

Question 17

What direction do the jet streams flow in the southern hemisphere and northern hemisphere?

Answer 17

West to East

Question 18

What is Buys Ballot Law?

Answer 18

In the Southern Hemisphere, if an observer stands with his back to the wing, pressure is higher on his left hand than his right.

Question 19

What is the explanation for jet streams?

Answer 19

The trapping of upward air by the tropopause layer, force the air to move toward the poles and as it does, the effect of Coriolis deflecting the air and the acceleration due to conversation of angular momentum creates the jet stream.

Question 20

Which side of the jet streams is turbulence likely to be greater?

Answer 20

Polar side