C13 The Earth's Atmosphere

Question 1

according to theory, what gases did volcanoes release into Earth’s early (first billion years) atmosphere

Answer 1

• volcanoes released NITROGEN, CARBON DIOXIDE and WATER VAPOUR,
• these gases formed the early atmosphere.

Question 2

according to theory, how were oceans formed?

Answer 2

oceans formed from water vapour (from volcanoes) condensing

Question 3

according to theory, what did the Earth’s early atmosphere mainly consist of?
which gases were there small proportions of?

Answer 3

mainly carbon dioxide
may have been small proportions of methane, ammonia and oxygen gas.

Question 4

according to theory, how did the amount of carbon dioxide in the Earth’s early atmosphere decrease?

Answer 4

• when oceans formed, carbon dioxide dissolved in them
• locked up in sedimentary rock and fossil fuels,
• from 2.7 billion years ago, more and more bacteria and algae evolved, photosynthesising which released oxygen and took in (so reduced carbon dioxide).

Question 5

how did animal forms start to evolve?
how did earliest living microorganisms react to this?

Answer 5

more plants evolved, more photosynthesis, more oxygen into atmosphere, allowing first animal forms to evolve, relying on algae and plants for food and oxygen to respire.
the earliest microorganisms had evolved without such high oxygen levels, so had little places to survive in and largely died out.

Question 6

proportion of gases in atmosphere today

Answer 6

78% nitrogen
21% oxygen
0.9% argon
0.04% carbon dioxide

Question 7

what type of radiation does the Earth’s surface emit?

Answer 7

long wavelength, infrared

Question 8

what type of radiation do greenhouse gases let pass through?
which type do they absorb?

Answer 8

short wavelength can pass through
they absorb long wavelength, infrared

Question 9

how do greenhouse gases increase the temp of Earth’s atmosphere?

Answer 9

they absorb long wavelength (infrared) radiation emitted from the Earth’s surface
the greenhouse gases trap the energy in the atmosphere
raising its temperature

Question 10

how does methane get into the atmosphere?

Answer 10

• more cattle (from their decomposing waste),
• rice fields,
• swamps,
• landfill sites.

Question 11

how has human activity increased the level of carbon dioxide in the atmosphere?

Answer 11

• burning fossil fuels releases carbon dioxide into atmosphere,
• deforestation means there are less trees to take it from the atmosphere for photosynthesis,
• climate change: temperature rises make carbon dioxide less soluble in water, so dissolve less in oceans.

Question 12

what is carbon footprint?

Answer 12

the total amount of greenhouse gases emitted over the full life cycle of a product, service or event

Question 13

how to reduce carbon dioxide emissions?

Answer 13

• use less fossil fuels,
• burn biofuels instead,
• use less electricity,
• plant more trees,
• home insulation to conserve energy,
• carbon capture and storage.

Question 14

how to reduce methane emissions

Answer 14

• lower demand for beef, plant-based diets,
• lower landfill.

Question 15

describe carbon capture and storage

Answer 15

-pump carbon dioxide released into atmosphere into underground fossil fuel power stations to be absorbed into porous rocks

Question 16

why is it a problem that fossil fuels all contain at least some sulphur impurities?

Answer 16

• the sulfur reacts with oxygen to form sulfur dioxide,
• this acidic gas is toxic and causes acid rain.

Question 17

when does incomplete combustion happen? what does it produce?

Answer 17

when fossil fuels are combusted with not enough oxygen
forming carbon monoxide

Question 18

why is carbon monoxide dangerous?

Answer 18

• it is picked up by haemoglobin in red blood cells in place of oxygen,
• meaning the body no longer has enough oxygen,
• meaning you can get drowsy, unconscious or die.

Question 19

how can nitrogen oxides form?
how can they be harmful?

Answer 19

• temperatures in engine are high during combustion,
• which allows the usually unreactive nitrogen gas to react with oxygen,
• forming nitrogen oxides,
  = which are toxic, cause acid rain and can trigger asthma.

Question 20

how can particulates enter the air from combustion in engines?

Answer 20

• when large hydrocarbon molecules in engines don’t burn completely,
• forming tiny solid particles of carbon and unburnt hydrocarbons which are carried into the air.

Question 21

impacts of carbon and unburnt hydrocarbon particulates in the air?

Answer 21

• global dimming (reflect sunlight back into space),
• could damage cells in lungs and cause cancer.

Question 22

products of combusting fossil fuels

Answer 22

sulfur dioxide
carbon dioxide
carbon/hydrocarbon particulates
nitrogen oxides
(incomplete): carbon monoxide