chemistry of the atmosphere Flashcards
(32 cards)
atmospheric gas proportions today
approximately 78% nitrogen approximately 21% oxygen small proportions of various other gases: - carbon dioxide - water vapour - noble gases.
why is evidence of he early atmosphere limited?
because of the time scale of 4.6 billion years, therefore theories about what was in the Earth’s early atmosphere and how the atmosphere was formed have changed and developed over time
gas proportions in early atmosphere
mostly carbon dioxide with little or no oxygen gas
reasons for the early atmosphere
intenseVOLCANIC activity that released gases - volcanoes also produced NITROGEN (which gradually built up in the atmosphere), - small proportions of methane and ammonia - water vapour formed oceans
how carbon dioxide decreased
- carbon dioxide dissolved in the ocean and
- carbonates were precipitated producing sediments
- photosynthesis (by algae and plants)
- formation of sedimentary rocks and fossil fuels that contain carbon
- marine aminals formed removing carbonates from the oceans to produce shells
how oxygen increased
- photosynthesis (by algae and plants)
word equation for photosynthesis
carbon dioxide + water –light energy–> glucose + oxygen
symbol equation for photosynthesis
6CO2 + 6H2O —> C6H12O6 + 6O2
how many years ago did the earth form?
4.6 billion years ago
when did the first photosynthetic organisms form?
2.7 billion years ago
name greenhouse gases
Water vapour
carbon dioxide
methane
explain the greenhouse effect
_sun emits SHORT wavelengt_h infrared radiation that enters the atmosphere and travels towards the Earth’s surface.
Earth ABSORBS some of this radiation
LONG wavelength radiation is REFLECTED back into the atmosphere.
Greenhouse gases can’t absorb the frequency of radiation emitted by the SUN (SHORT), but they can ABSORB the LONGER wavelength reflected radiation.
gases then RE-RADIATE this energy in all directions, including back towards Earth.
This increases the temperature at the Earth’s surface.
good use of the greenhouse effect
maintains temperatures on Earth high enough to support life
Human activities which contribute to an increase in greenhouse gases in the atmosphere
land fills (more decomposition which releases methane)
deforestation (less photosynthesis = less uptake of CO2)
agriculture (animals release methane during digestion)
burining fossil fuels (releases carbon in the form of CO2)
scientific concensus on greenhouse effect
human activities will cause the temperature of the Earth’s atmosphere to increase at the surface
and that this will result in global climate change
(all based on PEER-REVIEWED evidence)
models used for predictions of climate change
it is difficult to model such complex systems as global climate change
This leads to simplified models,
speculation and
opinions presented in the media (that may be based on only parts of the evidence and which may be biased)
potential effects of global climate change
polar ice caps melting (rise in sea levels, thus flooding, and no habitat for polar bears, coastal erosion)
meteorological events increase (extreme floods/droughts, storms and natural disaster)
changes in water availability (changes in species distribution)
changes in precitipation
foos shortages/ famine
define carbon footprint
total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event
how to reduce carbon footprint for INDIVIDUALS
(release of methane/carbon dioxide)
reduce waste
use renewable resources
maximise energy efficiency
carbon off-setting
how to reduce carbon footprint for GOVERNMENT
(release of methane/carbon dioxide)
emission caps
emission-based taxes
emission liscenes up to a certain cap (these must be bought)
carbon dioxide capture and storage technology
Barriers to Reducing Carbon Footprints:
economic reasons
government worries making changes required may restrict economic growth, this is a major concerns for developing countries
Barriers to Reducing Carbon Footprints:
social reasons
people in developed countries might not want to change lifestyle
there is a lack of education on the importance of changing lifestyle
Barriers to Reducing Carbon Footprints:
political reasons
countires have different opinions on how to act
countires they don’t know what other countires would do when presented with potential international agreement
uncertainty
scientists also disagree (on causes and solutions)
what is the major source of atmospheric pollutants
combustion of fuels
(most fuels, including coal, contain carbon and/or hydrogen and may also contain some sulfur)
