Solutions to the exercises page 82

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(Page 82)
12. Ozone absorbs harmful UV light. It is found in ozonosphere. Gases called CFCs are interfering with the formation of ozone.

13. The greenhouse effect is positive because it keeps the Earth warm enough for life to exist. But it can be also negative if there is an increase of greenhouse gases in the atmosphere, becase they cause more heat to be retained, increasing the temperature of the Earth.


Note for 2º A: page 78 underlined

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Unit 7 page 78

2º A – Homework 24/03/2014

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Worksheet 1 nº 3

1. The Sun has been active for 4.6 billion years.

2. Meteorology is the science which studies weather and climate.

3. Hail and snow are types of precipitation.

4. Clouds originate in low pressure areas.

5. Clouds near the ground form fog.

Worksheet 2 nº 1

1. The arrows represent warm air rising.

2. The air pressure is low in this area.

3. Clouds form when warm air rises, cools and condenses into water droplets.

Worksheet 2 nº 2

1. meteorology

2. satellites, weather stations

3. anticyclones

4. winds

5. clouds

6. hail

Worksheet 3 nº 3 (a)

See diagrams of sea and valley breezes, Student’s Book, page 79.

Page 79 nº 5

a. Coastal breezes are caused by warm air rising which pulls in cooler air;

b. day: sea breeze; night: land breeze.

 Page 79 nº 6

During the day, the air over the mountain slope heats up more than the air at the foot of the mountain. The warm air over the slope reduces in density and rises. A low pressure is created at the top of the mountain and high pressure from the cool air below forces a cool breeze to move upward. This condition generates a breeze which we call Valley breeze (winds that blow up the valley to the upper valley). It is very common during warmer months when there is a lot of heating from the sun.

Page 80 nº 7

Anticyclones are high pressure areas. Depressions are low pressure areas. Winds form because air tends to
move from high pressure areas to low pressure areas.

Page 80 nº 8

Rain is water droplets. Snow is frozen water vapour.

Page 84 nº 21

Because of the land breeze: the cooler air is being pulled in from the land towards the coast.

Page 84 nº 24

Upstream, because during the day, the heat creates winds that blow up the valley to the upper valley.

Page 84 nº 26

The reason why the water is cooler is because it has a higher specific heat capacity than air. This is the measure of heat energy required to increase the temperature of 1 kilogram of a substance by 1 ºC.
This means that the same heat coming from the Sun will increase the temperature of the air more than
the temperature of the water.

Page 84 nº 27

In the morning, there are less thermals, so the balloon has a smoother ride. Thermals are caused by hot air
rising from the warmed surface of the Earth.

Unit 7 – Answer key

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(Page 78)

03. The arrows for warm air go from the Equator to the poles. The arrows for cold air go from the poles to the Equator.
04. Around the Equator, the rays of the Sun are almost perpendicular to the ground. As a result, it makes the air
and the ocean water warm.
At the poles the rays are at an oblique angle. As a result, they do not warm up the ground and water.

As a result of the difference in temperature between poles and Equator, air and ocean currents are created. Warm air from the Equator moves towards the poles. Cold air from the poles moves towards the Equator.

As a result of the rotational movement of the Earth air and ocean currents form spirals.

(Page 84)

16. The warm air at the bottom rises because it is lighter
than the colder air at the top.
17. Individual answer based on the experiment,
Student’s book, page 77.
18. a. Hot water will rise, forming a current; b. along the
bottom of the tray.
19. Because of the rotation of the Earth.

Worksheet 3
Picture A:
rays perpendicular to the surface
Picture B:
rays at an oblique angle

Answer of part 2 in post “Perpendicular and oblique angles”

Test 7
1. In the Sun’s core.
2. Only a tiny fraction.
3. The Equator receives more solar energy because the
solar rays that reach it are almost perpendicular and
so sunlight is more direct.
4. Energy from the Sun and gravity.
5. Geological agents produce erosion, mass
movements and sedimentation.