earth and atmospheric science Flashcards
chapter 8
What did gases do from volcanic activity
Gases produced by volcanic activity formed the earths early atmosphere
what was the earths early atmosphere thought to have contained
little or no oxygen
a large amount of carbon dioxide
water vapour
small amounts of other gases
two processes that caused changes were
cooling of atmosphere and photosynthesis
how did cooling change the composition of the earths atmosphere
rainfall due to water
vapour condensing forming oceans
explain evidence that supports the idea that oxygen was not present in the early earths atmosphere
oxygen is not produced by volcanoes, other evidence is from iron based compounds which are present in very old rocks, that could have formed only if there was little or no oxygen
how does condensation of water vapour form oceans
the earth cooled down, causing water vapour in the atmosphere to condense to liquid water which then formed oceans
how did the amount of carbon dioxide in the atmosphere decrease
Carbon dioxide dissolved in the oceans. Sea creatures used the dissolved carbon dioxide to form shells made of calcium carbonate, this then allowed more carbon dioxide to dissolve in the oceans
Explain how the growth of primitive plants used Carbon dioxide and released Oxygen by photosynthesis and consequently the amount of oxygen in the atmosphere gradually increased
Some of the earths earliest photosynthetic organisms were cyanobacteria, which lived in shallow waters. These bacteria grow in huge colonies and produces sticky mucus. The mucus traps a layer of sediment, the organisms need to move this sediment layer in order to get sunlight. Over time the sediment layers build up to form rocky shapes called stromatolites. These provide evidence that photosynthetic organisms were living at this time. It is thought that microorganisms like these causes a rise in oxygen levels in oceans and then atmosphere. When land plants evolved there was another increase in oxygen levels
chemical test for oxygen
relight a glowing splint
explain the greenhouse effect
The earth emits infrared waves. Some gases in the air absorb energy transferred by these infrared waves. When the gases re-emit the energy, some of it goes back to the earths surface and warms it. The green house gases include carbon dioxide, methane and water vapour
state the influence of the greenhouse effect on the earth
greenhouse effect causes the earth to warm as when gases re emit energy, some of it foes back to earths surface and warms it
What is the correlation between the change in atmospheric carbon dioxide concentration, consumption of fossil fuels and temperature change
as consumption of fossil fuels increases, the carbon dioxide concentration increases therefore the green house effect will increase
what are the uncertainties
caused by location where these measurements are taken and the historical accuracy. The oldest continuous temperature records are for central England and they go back to 1659, these cannot asses global temperature chaange because it is only from one place. Earlier measurements weren’t very accurate
what is the composition of today’s atmosphere
main gas being nitrogen, increase in oxygen amounts, smaller proportions of gases such as carbon dioxide, water vapour and argon
what are the potential effects on the climate of increased levels of carbon dioxide and methane, generated by human activity including burning fossil fuels and livestock farming
causes ice at the south pole and glaciers to melt
extra water raises sea levels
increased flooding
higher average temperature results
animals will move away from their natural habitats to find cooler areas
some animals and plants may become extinct if they cannot survive at warmer temperatures or dins new places to live
more extreme weather events
changes weather patterns
effects crops
