C13 - The Earth's Atmosphere

Question 1

What is the atmosphere made up of today

Answer 1

• Around 80% N₂
• Around 20% O₂
• 0.9% Argon
• 0.04% CO₂
• Trace other gases

Question 2

Common theory for how the early atmosphere was formed

Answer 2

Intense volcanic activity released gases

Question 3

What was the early atmosphere composed of and what was it like

Answer 3

• Some N₂, other amounts of CO₂ and H₂O
• Trace amounts of NH3 and CH4
• Similar to atmosphere of Mars or Venus

Question 4

How were the oceans formed?

Answer 4

• The Earth cooled down
• This condensed the water vapour in the atmosphere

Also allowed plants to grow

Question 5

How did Oxygen levels in the atmosphere increase

Answer 5

• Plants and algae photosynthesised
• This produced O₂

Question 6

How did CO₂ levels in the atmosphere decrease

Answer 6

• Dissolved in oceans forming carbonates and then precipitated to form sedimentary
• Micro-organisms died and fell into sediment, forming carbon fossil fuels
• Plants and algae photosynthesised

Question 7

How did ammonia and methane levels in the atmosphere decrease

Answer 7

• They reacted with oxygen to form either CO₂ and water vapour or N₂ and water vapour

Question 8

How was coal formed

Answer 8

• Ferns and trees die in wetlands
• The conditions prevented oxidation
• High pressure and temp. formed coal

Question 9

How was crude oil and natural gas formed

Answer 9

• Micro-organisms (plankton) died in the sea
• Their remains got buried by sediment (lack of O₂)

Question 10

Name 3 Greenhouse Gases

Answer 10

• Co₂
• Methane
• Water Vapour

Question 11

Describe the greehouse effect

Answer 11

• Shortwave radiation from Sun passes through atmosphere
• Earth absorbs these and then radiates them as longwave IR
• This is absorbed by greenhouse gases and emitted back down which warms the atmosphere

Question 12

Human activities that increase Co₂

Answer 12

• Burning fossil fuels
• Deforestation

Question 13

Human activities that increase methane

Answer 13

• Growing rice in flooded paddy fields
• Cattle farming

Question 14

Effects of climate change

Answer 14

• Melting ice caps + rising sea levels
• Extreme weather
• Famine + drought
• Distribution change in animals (migration)
• Loss of biodiversity and habitat

Question 15

Why do many scientists believe in climate change

Answer 15

• Evidence is shared between them
• This is a peer review process and it avoids false claims or bias

Question 16

Why is information about climate change hard to communicate

Answer 16

• It is hard to model and there are uncertanties e.g. how much the temperature will rise
• This means it has to be simplified for the general public
• This can lead to bias or speculation

Question 17

Defenition of a carbon footprint

Answer 17

The total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event

Question 18

Ways to reduce carbon footprint

Answer 18

• Insulating homes
• Using public transport
• Renewable electricity sources
• Eat less beef and dairy
• Trapping methane

Question 19

Problems with reducing carbon footprint

Answer 19

• Solutions are expensive
• Can be inconvenient

Question 20

What is carbon monoxide and how is it formed

Answer 20

• It is a toxic, colourless gas
• Formed from incomplete combustion

Question 21

How is sulfur dioxide formed

Answer 21

• Some fuels have sulfur in them
• this is then oxidised

Question 22

How are oxides of nitrogen formed

Answer 22

• High pressure and temperature inside diesel engines

Question 23

Problems with sulfur dioxide and oxides of nitrogen

Answer 23

• Cause respiratory problems
• Form acid rain which damages infrastructure and kills organisms

Question 24

How are particulates formed and problems with them

Answer 24

• Unburned hydrocarbons and carbon in engines
• This is due to incomplete combustion due to insufficient oxygen
• Cause health problems such as heart disease
• Cause global dimming which affetcs rainfall patterns

Question 25

Problems with increased carbon dixoide emissions

Answer 25

• It is a greenhose gas so traps more heat increasing teh surface temperature
• This causes global warming and clomate change
• Leads to polar ice caps melting, sea levels rising
• Leads to flooding + other extreme weather events (droughts)
• Reduction in biodiversity