Topic 9- The evolution of the atmosphere

Question 1

how much nitrogen is there in our atmosphere

Answer 1

about four-fifths (approximately 80%)

Question 2

how much oxygen is there in our atmosphere

Answer 2

about one-fifth (approximately 20%)

Question 3

what are the other gases in our atmosphere

Answer 3

carbon dioxide,

water vapour and noble gases.

Question 4

why is evidence for the early atmosphere limited

Answer 4

because of the time scale of 4.6 billion years.

Question 5

What did volcanoes do to the atmosphere?

Answer 5

-intense volcanic activity that released gases that formed the early atmosphere.
-water vapour that condensed to form the oceans.
- it consisted of mainly carbon dioxide with little or no oxygen gas
-volcanoes also produced nitrogen which gradually built up in the atmosphere
-may have been small proportions of methane
and ammonia.

Question 6

what did oceans do to the atmosphere?

Answer 6

-water vapour condensed to form the oceans
-carbon dioxide dissolved in the water and
carbonates were precipitated producing sediments, which reduced the amount of carbon dioxide in the atmosphere.

Question 7

how did oxygen increase?

Answer 7

• Algae and plants produced the oxygen by photosynthesis, that is now in the atmosphere today
• Algae first produced oxygen about 2.7 billion years ago
• Over the next billion years plants evolved and the percentage of oxygen gradually increased to a level that enabled animals to evolve.

Question 8

how did carbon dioxide decrease?

Answer 8

-Algae and plants decreased it by photosynthesis
- by the formation of sedimentary
rocks and fossil fuels that contain carbon
-locked up in rocks and fossil fuels after the organisms died

Question 9

explain the formation of deposits of limestone

Answer 9

• sedimentary rock

- made of calcium carbonate deposits from the shells and skeletons of marine organisms.

Question 10

explain the formation of coal crude oil and natural gas

Answer 10

• when plants plankton and marine animals die they fall to the seabed
• these get buried by layers of sediment
• over millions of years, they become compressed and formed sedimentary rocks, oil and gas, trapping co2 in them

Question 11

what do greenhouse gases in the atmosphere do

Answer 11

maintain temperatures on Earth high enough to support life

Question 12

give some greenhouse gases

Answer 12

Water vapour, carbon dioxide and

methane

Question 13

what’s the greenhouse effect in terms of long and short length radiation

Answer 13

• all particles absorb certain frequencies of radiation
• greenhouse gases dont absorb the incoming short wavelength radiation from the sun
• they do absorb the long wavelength radiation that gets reflected back off the earth
• they then re-radiate it in all directions, including back to Earth
• longwave radiation is thermal radiation, so results in warming of the earth.

Question 14

give forms of human activity which affect the amount of greenhouse gases in the atmosphere

Answer 14

deforestation- fewer trees makes less CO2 is removed from the atmosphere via photosynthesis

burning fossil fuels- carbon that was locked up in these fuels is released

agriculture- more farm animals produce methane through digestion

creating waste- more landfill sites and more waste from agriculture means more co2 and methane released by decomposition of waste.

Question 15

give four consequences or climate change?

Answer 15

• polar ice caps melting, causing a rise in sea levels, increased flooding and coastal erosion.
• changes in rainfall patterns - food production
• frequency and severity of storms
• changes in temperature and amount of water available in a habitat- differences in distribution of a species

Question 16

what is carbon footprint

Answer 16

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

Question 17

describe some actions to reduce emissions of carbon dioxide and
methane

Answer 17

• renewable energy sources
• more efficient processes could conserve energy or cut waste, as when waste decomposes, it releases methane.
• tax cars that release more co2
• put cap on emissions of companies
• technology can capture the c0s before its released into the atmosphere, it can then be stored deep underground

Question 18

why might actions to reduce the carbon footprint be limited?

Answer 18

• still a lot of work needed on alternative technologies
• affect economic growth of communities, which could be bad for people’s well-being for countries that are still developing.
• hard to make international agreements.
• hard to get everyone on board- education is needed

Question 19

what’s a major source of atmospheric pollutants

Answer 19

The combustion of fuels

Question 20

what do most fuels, including coal, contain?

Answer 20

carbon and/or hydrogen (hydrocarbons) and may also contain some sulfur

Question 21

what happens during combustion of fossil fuels?

Answer 21

carbon and hydrogen are oxidised so that co2 and water vapour are released into the atmosphere

Question 22

whats happens to the fuels when there’s lots of oxygen?

Answer 22

all the fuel burns- complete combustion

Question 23

what happens to fuel when there isn’t enough oxygen?

Answer 23

some of the fuel doesn’t burn- incomplete combustion

under these conditions, solid particles (particulates) of soot (carbon) and unburnt fuel are released and carbon monoxide can be produced as well ads co2.

Question 24

what problems can particulates in the air cause

Answer 24

if particulates are inhaled, they can get stuck in the lungs- respiratory problems

they’re bad for the environment- reflect sunlight back into space- global dimming

Question 25

what problems can carbon monoxide cause

Answer 25

toxic

colourless and odourless so hard to detect

Question 26

name other substances released when burning fossil fuels

Answer 26

oxides of nitrogen, sulfur dioxide, carbon monoxide

Question 27

when is sulfur dioxide released?

Answer 27

during combustion of fossil fuels, such as coal, that contain sulfur impurities- the sulfur in the fuel becomes oxidised

Question 28

when is nitrogen oxides released?

Answer 28

when the nitrogen and oxygen in the air react, because of the heat of the burning

Question 29

what happens when nitrogen oxides and sulfur dioxide react with clouds?

Answer 29

they form dilute sulfuric acid or dilute nitric acid

this falls as acid rain

Question 30

what else is bad about when nitrogen oxides and sulfur dioxide

Answer 30

bad for health- respiratory problems

Question 31

whats released in incomplete combustion

Answer 31

soot, unburnt fuel and carbon monoxide

Question 32

why is evidence of human activity reliable

Answer 32

its been peer reviewed

Question 33

why is it difficult to understand the worlds climate

Answer 33

its very complex and there are a lot of variables involved

Question 34

why is there speculation in the media

Answer 34

some poeple may be biased or not all the information is given