The Earth's Sea and Atmosphere

Question 1

What is the atmosphere?

Answer 1

An envelope of different gases (air) surrounding Earth

Question 2

Why is Earth different to other planets in our solar system?

Answer 2

It has an atmosphere that can support life

Question 3

What is the composition of today’s atmosphere?

Answer 3

Nitrogen: 78%
Oxygen: 21%
1% other gases:-
Argon: 0.93%
Carbon dioxide: 0.035%
Varying amounts of water vapour
Trace amounts of other gases

Question 4

How has the atmosphere changed from 4.5 billion to today?

Answer 4

At first there was no atmosphere
Then the surface cooled and formed a solid crust
Volcanoes formed and released Carbon Dioxide, Methane, Steam and Ammonia
The Earth cooled even more and the steam condensed to form the oceans
Trees and animals evolved

Question 5

What did the early atmosphere contain?

Answer 5

Little or no oxygen
A large amount of carbon dioxide
Water vapour and a small amount of other gases

Question 6

How can you figure out the amount of oxygen in the atmosphere?

Answer 6

By oxidising copper.
Move 100cm^3 of air over copper while heating it. Only the oxygen will react with the copper, so the amount of air left will have no oxygen.
Therefore 100 minus the amount of air left will give you the oxygen content of air.

Question 7

How were cyanobacteria and stromatolites useful in the development of the atmosphere?

Answer 7

They were the first organisms to photosynthesise, which created oxygen, allowing other organisms to develop

Question 8

What is the chemical formula for ozone?

Answer 8

O3

Question 9

Where is the ozone layer found?

Answer 9

In the stratosphere

Question 10

Why was the ozone layer important in the development of the atmosphere?

Answer 10

It blocks harmful radiation from the sun which can damage and kill life on Earth

Question 11

Why did the amount of ammonia in the atmosphere go down?

Answer 11

It reacted with oxygen in the atmosphere to form nitrogen and water:
4NH3 + 3O2 —-> 2N2 + 6H2O

Question 12

What were iron bands?

Answer 12

Iron bands were made of iron oxide or rust. The iron came from volcanic activity in the oceans and the oxygen came from stromatolites photosynthesising. They prevented the oxygen level from rising for a few billion years because they were using up the oxygen being produced. They eventually went away because there was so much life producing oxygen the iron was deposited where it formed.

Question 13

What is the global average temperature and what would it be without the greenhouse effect?

Answer 13

It is 13 degrees Centigrade, compared to -22 degrees Centigrade without the greenhouse effect.

Question 14

What are the stages of the greenhouse effect?

Answer 14

Stage 1: Radiation from the Sun in the form of light waves enters the atmosphere and warms the Earth
Stage 2: Infrared radiation is produced by the Earth. Some of this heat travels through the atmosphere and escapes into space
Stage 3: Some of this heat is absorbed by greenhouse gases in the atmosphere and so is reflected back to Earth. This causes the temperature of the Earth to rise
Stage 4: Increased levels of greenhouse gases in the atmosphere trap more of the emitted heat. This leads to a greater increase in hte Earth’s temperature

Question 15

What are the three main greenhouse gases?

Answer 15

Water vapour, methane and sulphur dioxide

Question 16

What are the effects of global warming?

Answer 16

Rising sea levels
Shrinking ice caps
More extreme weather
Malaria moving northwards
Species going extinct
More extreme heatwaves
Disruption to the gulf stream

Question 17

How much more powerful is methane than carbon dioxide p?

Answer 17

23 times

Question 18

What is permafrost?

Answer 18

Frozen plants and soil

Question 19

How does melting permafrost release greenhouse gases?

Answer 19

Permafrost melts
Plants go to the bottom of lakes
Plants ferment and produce methane
Methane gets trapped in ice
Ice melts and methane is released into atmosphere

Question 20

What are some ways of reducing climate change?

Answer 20

Iron seeding
Converting CO2 into hydrocarbons
Hydrogen fuel
Carbon capture and storage

Question 21

What is iron seeding?

Answer 21

Putting iron in the oceans to stimulate phytoplankton growth. The increased amount of phytoplankton will then photosynthesise more, reducing carbon dioxide and increasing oxygen in the atmosphere

Question 22

What is hydrogen fuel?

Answer 22

A fuel that does not produce any greenhouse gases when reacting with oxygen, only water.
However, it is currently made by reacting steam with natural gas or coal, both of which are greenhouse gases. It is also very flammable and may explode if handled incorrectly

Question 23

How can carbon dioxide be converted into hydrocarbons?

Answer 23

Reacting CO2, water and sunlight produces carbon and hydrogen, which can be combined to make hydrocarbon, which can be used as a fuel