Topic 8 -Earth's atmosphere

Question 1

What formed the Earth’s atmosphere?

Answer 1

1) The gases produced by volcanic activity formed the Earth’s early atmosphere.

Question 2

What was the Earth’s surface like millions year’s ago?

Answer 2

1) The Earth’s surface was originally molten for many millions of years. There was almost no atmosphere.

Question 3

What happened to the Earth’s surface?

Answer 3

1) Eventually the Earth’s surface cooled and a thin crust formed, but volcanoes kept erupting, releasing gases from inside the Earth. This ‘degassing’ released mainly carbon dioxide, but also steam, methane and ammonia.

Question 4

What was the early atmosphere made out of?

Answer 4

1) When things eventually settled down, the early atmosphere was mostly CO2 and water vapour. There was very little oxygen.
2) The water vapour later condensed to form the oceans.

Question 5

What happened to the CO2 in the early atmosphere?

Answer 5

1) A lot of the early CO2 dissolved into the oceans.

Question 6

How was nitrogen put into the atmosphere?

Answer 6

1) Nitrogen gas (N2) was then put into the atmosphere in two ways- it was formed by ammonia reacting with oxygen and was released by denitrifying bacteria.

Question 7

What happened to the nitrogen?

Answer 7

1) Nitrogen isn’t very reactive. So the amount N2 in the atmosphere increased, because it was being made but not broken down.

Question 8

What did the green plants do?

Answer 8

1) Green plants evolved over most of the Earth. As they photosynthesised, they removed the CO2 and produced O2.

Question 9

How did the amount of CO2 reduce?

Answer 9

1) Thanks to the plants, the amount of O2 in the air gradually built up and much of the CO2 eventually got locked up in fossil fuels and sedimentary rocks.

Question 10

What happened to the water vapour?

Answer 10

1) The early atmosphere was probably mostly carbon dioxide, with little or no oxygen. There were smaller proportions of water vapour, ammonia and methane. As the Earth cooled down, most of the water vapour condensed and formed the oceans.

Question 11

What did the build of oxygen do in the atmosphere?

Answer 11

1) The built of oxygen in the atmosphere killed off early organism that couldn’t tolerate it.
2) But it did allow the evolution of more complex organisms that made use of the oxygen.
3) The oxygen also created the ozone layer (O3) which blocked harmful rays from the sun and enabled even more complex organisms to evolve.
4) There is no C02 left now.

Question 12

How can you test for oxygen?

Answer 12

1) You can test for oxygen by checking if the gas will relight a glowing splint.

Question 13

Which radiation does the sun give out?

Answer 13

1) The sun gives out electromagnetic radiation.

Question 14

What happens to the EM radiation?

Answer 14

1) Some electromagnetic radiation, passes through the atmosphere.

Question 15

What happens to the short EM radiation?

Answer 15

1) The electromagnetic radiation with short wavelengths is absorbed by the Earth- warming our planet.

Question 16

What are the greenhouse gases?

Answer 16

1) Greenhouse gases are the gases in the atmosphere that can absorb and reflect heat radiation. They’re only present in small amounts. Carbon dioxide, water vapour and methane are the three greenhouse gases.

Question 17

How are the greenhouse gases absorbed by the earth? (PROCESS)

Answer 17

1) The Earth radiates some of the heat radiation it absorbs as longer wavelength, infrared (IR) radiation.
2) Some of this IR radiation is absorbed bu the greenhouses gases.
3) Some of the IR radiation is reflected back to the Earth by the greenhouse gases.
4) Some IR radiation is re-emitted back into space.
5) The absorption and reflection of IR radiation by greenhouse gases is what keeps the Earth warm. It is called the greenhouse effect.

Question 18

What happens if the concentration of the greenhouse gas increases?

Answer 18

1) If the concentration of greenhouse gases in the atmosphere increases, you get an enhanced greenhouse effect. This is where most heat radiation from the Earth is absorbed and less is re-emitted back into space. This cause the atmosphere to heat up.

Question 19

How does human activity affect the composition of air?

Answer 19

1) If the population has increase it means that more people will need more energy for lighting, heating, cooking, transport and so one. People’s lifestyle is also changing, more and more countries are becoming industrialized.
2) This means the average energy demand per person is also increasing (since people have more electrical devices, etc). This increased energy consumption comes mainly from the burning of fossils fuels which releases more CO2.
3) More people also means more land is needed to build houses and grow food. This space is often made by chopping down tress- deforestation. So fewer plants means less carbon dioxide is taken out of the atmosphere.
4) CO2 is also produced by volcanoes erupting,

Question 20

How is methane creating problems?

Answer 20

1) Methane is causing problems. The concentration of methane has risen lots in recent years due to increased human activity,
2) Methane is produced the digestive processes of certain livestock (Cattle, goats and camels). So, the more livestock we farm, the more methane is produced.
3) The increasing concentration of methane is an issue as it’s a super effective greenhouse gas.

Question 21

What is global warming?

Answer 21

1) Global warming is a type of climate change and causes other climate changes e.g. changing rainfall patterns. It could also cause severe flooding due to the polar ice caps melting.
2) Most scientific communities agree that global warming is anthropogenic (caused by humans).

Question 22

How can we prevent or slow down climate change?

Answer 22

1) To reduce carbon dioxide emissions, we can try to limit our own use of fossil fuels. This could be doing things like walking or cycling instead of driving or turning your central heating down.
2) The government has formed plans to encourage the public to become more energy efficient to create financial incentives to reduce CO2 emissions, to use more renewable energy.