4: Earth’s Atmosphere

Question 1

What was the Earth’s early atmosphere formed by?

Answer 1

Volcanic activity. These volcanoes released the gases that formed the atmosphere.

Question 2

What was the early atmosphere primarily composed of?

Answer 2

Carbon Dioxide and water vapour. Nitrogen also, and small amounts of methane and ammonia.

Question 3

What happened to the water vapour in the Earth’s early atmosphere?

Answer 3

Condensed to form the oceans as the Earth cooled.

Question 4

What happened to the Carbon Dioxide in the Earth’s early atmosphere?

Answer 4

-Carbon Dioxide dissolved into the oceans to form a weak acid, reacted with minerals in the sea to form precipitates.
-Over time, precipitates formed sediments of carbonate rock on the sea bed.
-Carbon Dioxide in the sea was used to make coral and shells of animals. Formed sedimentary rock, like limestone.
-Photosynthetic algae evolved in the oceans, producing oxygen. Plants evolved to produce more oxygen.
-Carbon became trapped in fossil fuels.

Question 5

When did photosynthetic algae first evolve in the oceans?

Answer 5

3 billion years ago.

Question 6

What did photosynthetic plants and algae do?

Answer 6

Reduced Carbon Dioxide levels, increased Oxygen levels to the point where animals could evolve.

Question 7

What does the Earth’s current atmosphere primarily consist of?

Answer 7

Nitrogen (80%)
Oxygen (19%)
Other gases (1%)

Question 8

How do we reduce greenhouse gases in the atmosphere?

Answer 8

Reducing the use of fossil fuels, mainly by using alternative sources of energy, and conserving energy.

Question 9

State the effects of the mean temperature of the Earth increasing.

Answer 9

-Polar ice caps melting
-Sea levels rising
-Patterns of rainfall changing
-Frequent and intense droughts
-Higher intensity storms
-Extreme heat waves and rainfall

Question 10

Explain why the increase in population causes the increase in carbon dioxide in the atmosphere

Answer 10

As world population increases, the demand for electricity and heating increases, so more fossil fuels are being burnt. This leads to an increase in Carbon Dioxide in the atmosphere.

Question 11

Explain why the increase in world population caused the increase in the concentration of methane in the atmosphere.

Answer 11

Population increases, so the demand for food increase, so scale of agriculture increases. More methane is being released into the atmosphere by livestock

Question 12

Why don’t some scientists accept the theory that the temperature of the Earth has increased because of the increase in greenhouse gases in the atmosphere?

Answer 12

-Greenhouse gases absorb only a small part of the radiation emitted by Earth

Question 13

What happens when hydrocarbon fuels are burnt in plenty of air?

Answer 13

The Carbon and Hydrogen in the fuel are completely oxidised. They produce Carbon Dioxide and Water.

Question 14

When Sulphur impurities in fuels are burnt, what do they form?

Answer 14

Sulphur Dioxide, which can cause acid rain.

Question 15

What does Sulphur Dioxide do (in relation to environmental damage)?

Answer 15

Causes acid rain.

Question 16

What does soot cause (in relation to environmental damage)?

Answer 16

Global dimming.

Question 17

What is the main reason as to why the amount of Carbon Dioxide in the Earth’s atmosphere has risen in the recent past?

Answer 17

The large amount of fossil fuels being burnt.

Question 18

What are the 3 main greenhouse gases?

Answer 18

Carbon Dioxide, Water Vapour and Methane.

Question 19

How do greenhouse gases lead to global warming?

Answer 19

Greenhouse gases absorb long wave radiation, stopping it travelling back out into space, making it touch the Earth’s surface again increasing the temperature

Question 20

Explain how reducing the amount of sulphur in fossil fuels reduces the erosion of limestone.

Answer 20

When the sulphur dissolves in water, Sulphur Dioxide is formed, which causes acid rain. If we reduce the amount of sulphur, we reduce the amount of sulphur dioxide in the air, making the rain less acidic, and reduces the erosion of limestone.

Question 21

Nitrogen passes through car engines. Explain why oxides of nitrogen are formed in car engines.

Answer 21

Car engines work at high temperatures, so the nitrogen and oxygen from the air react with eachother in the engine.

Question 22

What are the key two main activities that increase carbon dioxide levels?

Answer 22

Deforestation and burning fossil fuels.

Question 23

What are the two key activities that increase methane levels?

Answer 23

Animal farming and rice farming.

Question 24

What is peer review?

Answer 24

Where other experts check scientists’ work to make sure it was done properly.