2.2 The global energy budget

Question 1

What are winds?

Answer 1

Moving air masses - large bodies of air which are almost uniform horizontally in temperature and moisture characteristics. They are separated from adjacent different air masses by frontal zones.

Question 2

What are air masses classified as?

Answer 2

1) Continental or maritime

2) Arctic, Antarctic, equatorial, tropical, or polar

Question 3

What is the temperature and humidity at equatorial maritime?

Answer 3

Warm and very moist e.g. Indian ocean

Question 4

What is the temperature and humidity at tropical maritime?

Answer 4

Mild in winter, warm in summer; moist, e.g. N/S Atlantic

Question 5

What is the temperature and humidity at tropical continental?

Answer 5

Very warm and dry. e.g. Australia

Question 6

What is the temperature and humidity at polar maritime?

Answer 6

Cool and moist e.g. Arctic ocean

Question 7

What is the temperature and humidity at polar continental?

Answer 7

Cold and dry e.g. Canada

Question 8

What is the temperature and humidity at continental arctic and Antarctic?

Answer 8

Very cold and very dry e.g. Antarctic

Question 9

What is the Coriolis effect?

Answer 9

Due to the Earth’s rotation, winds can’t travel is straight lights; they are deflected.

Question 10

What is the speed of air movement determined by?

Answer 10

The pressure gradient. Steep gradient = strong winds - close isobars

Question 11

What is Ferrel’s Law?

Answer 11

Any moving body in the northern hemisphere will be deflected to its right and any moving body in the southern hemisphere will be deflected to its left.

Question 12

What are the trade winds?

Answer 12

Surface winds blowing in the Hadley cell are deflected to the west

Question 13

What are the polar easterlies?

Answer 13

Surface winds in the polar cell moving towards the equator are deflected to the right in NH or left in SH.

Question 14

What are the prevailing westerlies?

Answer 14

Surface winds in the Ferrel cell are blowing in a different direction to the two cells either side of them. Northwards in NH, southwards in SH. Winds in NH are deflected to the right, winds in SH are deflected to the left.

Question 15

What are the Doldrums?

Answer 15

Nickname given to the area (0-5ºN/S) around the equator, that serves as the meeting place for the two trade winds in each hemisphere. Leads to very calm waters.

Question 16

What are the horse latitudes?

Answer 16

30º N/S where cool descending air creates period of calm weather

Question 17

Why do winds near the surface lose energy and speed?

Answer 17

Due to friction, reducing geostrophic force. As a result, pressure gradient force is no longer balanced by the Coriolis force.

Question 18

What are the upper westerlies?

Answer 18

Fast moving westerly winds between 30 and 50 degrees. Occur at the top of the troposphere.

Question 19

What are the causes of the upper westerlies?

Answer 19

1) Temperature/pressure gradient = they blow in response to the strong difference in temperature gradient between polar and tropical air meeting. This generates a high-pressure gradient.
2) Coriolis force - causes air to deflect east as it travels towards the poles and become geostrophic.

Question 20

What is a jet stream?

Answer 20

A narrow ribbon if very fast-moving air that runs through the centre of Rossby waves. There are 2 jet streams in each hemisphere: Polar jet stream and sub-tropical jet stream.

Question 21

What are Rossby waves?

Answer 21

When temperature and pressure gradients weaken, the jet stream can meander in large curving paths known as Rossby waves.
They are belts of upper-air westerlies, which follow a meandering path around the earth.
When they meander in large curving paths it can lead to the separation of ‘pools’ of warmer air surrounded by colder air, or vice versa. They help transfer heat north and cold south. They are much slower moving than the jet streams.
They may be caused by a disturbance in the airflow.

Question 22

Where is the polar front jet stream found?

Answer 22

Between 40-60ºN/S - forms the division between Ferrel and polar cells.

Question 23

Where is the sub-tropical jet stream found?

Answer 23

25-30ºN/S, marking the boundary between the Hadley cell and Ferrel cell.