chemistry of the atmosphere Flashcards
(38 cards)
what was the earths surface like 4.5 bn years ago
originally molten for millions of years, eventually things cooled down and a thin crust formed, but volcanoes continued erupting
what gases were there 4.5 bn years ago
- intense volcanic activity
- early atmosphere is mostly CO2, some N2 and O2
- possibly water vapour too
what is the evidence for the gases there were billions of years ago
- similar to the atmosphere of Venus and mars today
- comes from gases released by volcanoes today
how did the first clouds form
as earth cooled, water vapour in the atmosphere condensed
what happened to most of the carbon dioxide that was released in volcanic eruptions
gradually removed from the atmosphere
how was the CO2 removed from the atmosphere
- oceans are a natural store of CO2
- when oceans formed a lot of CO2 from the atmosphere dissolved into them
- green plants and algae evolved over most of the Earth. they absorbed some of the CO2 and used it for photosynthesis.
what happened as green plants and algae evolved
CO2 was removed and O2 is added to the atmosphere
how has long has the earths atmosphere stayed relatively the same
200 million years
what are the main gases in the atmosphere now
- nitrogen (78%) and oxygen (21%)
- other gases that make up 1% include CO2, water vapour and noble gases
what happened to the CO2 that was absorbed from the atmosphere by green plants and algae
- green plants and algae that absorbed it died, buried under sediment, along w/ shells and skeletons of marine organisms that had slowly evolved
- formed fossil fuels
what happened to the CO2 that was dissolved from the atmosphere into the oceans
- insoluble compounds became sediment and formed sedimentary rock
- soluble compounds taken in by animals, animals w/ shells/skeletons die and become part of sediment
- form sedimentary rock
what are greenhouse gases
gases in the atmosphere that maintain temps. on earth high enough to support life
- carbon dioxide
- methane
- water vapour
explain the greenhouse effect
1) short wavelength radiation emitted by sun enters earths atmosphere
2) this radiation is absorbed by earth warming it up
3) long wavelength radiation is emitted from earth
4) greenhouse gases absorb some of this long wavelength radiation
5) they re-radiate this radiation in all directions including towards earth, warming it up
what human activities increase carbon dioxide in the atmosphere
- burning fossil fuels for electricity/running cars
- deforestation, cutting down trees reduces co2 that us absorbed by photosynthesis
what human activities increase methane in the atmosphere
- cattle producing methane, cattle reared for humans to eat or milk
- the decay of landfill sites by microorganisms
what do most scientists believe ab earths temp.
that human activities will cause temperature of earth’s atmosphere to increase at the surface, causing global climate change
what is the theory of climate change based on
peer-reviewed evidence
what is peer-reviewed evidence
- conclusions from new scientific research are reviewed or checked by other scientists. they look at the method used, the accuracy of the results and the conclusions drawn.
- ensure bias is avoided and to have confidence in what they are being told ab
what are the problems w/ modelling climate change
- modelling something so complex is difficult
- scientists have a duty to report any uncertainties in their models
- non-scientists w/ a vested interest may present a biased opinion on only part of the evidence in the media
what are the effects of global warming
- rising sea levels
- melting ice caps
- increased natural disasters
- loss of habitat
what are the effects of weather changes
- extreme weather events more frequent and severe
what are the effects of extinction
- as climate changes rapidly animals and plants are unable to adapt to changing environment and die out
what is a carbon footprint
total amount of CO2 or other GHGs emitted over a the full life cycle of a product service or event
what are ways to decrease our carbon footprint
> eating less meat - reduces methane
using public transport or walking - reduces CO2
recycle more - less rubbish in landfill so less methane
taxation of polluting vehicles - encourages people to walk or take public transport - reduces CO2
carbon capture and storing in rocks - reduces CO2
