Global Circulation Model

Question 1

What are winds?

Answer 1

Large scale movements of air caused by differences in air pressure

Question 2

What are the differences in air pressure caused by?

Answer 2

Atmospheric heat variations

Question 3

What are the 3 cells in the tri-cellular model?

Answer 3

Hadley
Ferrel
Polar

Question 4

What is the Coriolis effect?

Answer 4

The rotation of the earth causes winds to veer to the right (N.hemisphere) and left (S.hemisphere)

Question 5

Above 60 degrees latitude in the northern hemisphere what are the winds called?

Answer 5

Polar easterlies

Question 6

What are the winds between 30 and 60 degrees north called?

Answer 6

South westerlies

Question 7

What are the winds between the equator and 30 degrees north called?

Answer 7

North-easterly trade winds

Question 8

What are the winds between the equator and 30 degrees south called?

Answer 8

South-easterly trade winds

Question 9

What are the winds between 30 and 60 degrees south called?

Answer 9

North- westerlies

Question 10

What are the winds between 60 and 90 degrees south called?

Answer 10

Polar easterlies

Question 11

Explain the Hadley cell

Answer 11

• Air rises from the equator as it is warm
• Air expands, cools and reaches dewpoint near to the tropopause density increases and cumulonimbus clouds are created.
• As uplift ceases it moves away from the equator
• The Coriolis force causes air to slow down and subside at around 30 degrees latitude
• Creates sub-tropical high pressure belt
• Creates clear skies and dry stable conditions
• Some air is returned to the equator as north-east trade winds due to pressure gradient and forms fhe descending limb of the Hadley cell

Question 12

Explain the Ferrel cell

Answer 12

• The cool air that reaches the ground becomes surface winds
• Trace winds - towards equator, converge in East to form ITCZ
• Westerlies - move towards poles (tropical maritime air)
• N.hemisphere - winds from the Caribbean area are diverted polewards forming warm south - westerlies
• Collect moisture as track along the sea
• At 60 degrees it meets cold air moving south (polar front)
• Warmer air rises as less dense
• Low pressure
• Some air forms the descending limb of the Ferrel cell and moves back towards the equator

Question 13

Explain the Polar cell

Answer 13

• Some the air at the polar front travels towards the poles where, having lost heat, it sinks forming an area of high pressure
• Air returning to the polar front does so as cold polar eateries (air returns south due to difference in pressure)

Question 14

What % of heat transfer is through ocean currents?

Answer 14

20%

Question 15

What are ocean currents?

Answer 15

Large scale movements of water caused by differences in water density

Question 16

What does water density depend on?

Answer 16

Temperature

Salinity

Question 17

What are ocean currents affected by?

Answer 17

Surface winds
Position of land masses
Other currents

Question 18

What is the role of ocean currents?

Answer 18

Transfer heat from warmer to cooler areas

Question 19

What effect do warm currents have?

Answer 19

Warm areas

Question 20

In the N.hemisphere in which direction do ocean currents move?

Answer 20

Clockwise

Question 21

In the S.hemisphere which way do oceans currents move?

Answer 21

Anti-clockwise

Question 22

What affect do surface winds have on ocean currents?

Answer 22

Equator - push water west

Between 30 and 60 degrees - push water east