Chapter 13 - The Earth's atmosphere Flashcards
how long ago was the earth formed?
4.6 billion years ago
how do scientists collect data on what the earth was like? 2
gas bubbles trapped in rocks
data gathered from other planets and their moons
what was the first phase in the evolution of the atmosphere?
the surface was covered in volcanoes which released gases (CO2 and oxygen)
then nitrogen, water vapour, methane and ammonia were released by volcanoes
what gases would the early atmosphere be made from?
mostly carbon dioxide and a little oxygen
how were oceans formed? (2 theories)
water vapour in the atmosphere condensed as the planet cooled
icy comets melted and released water
what happened to the CO2 in the atmosphere once oceans were formed?
it dissolved into the water and formed carbon precipitates that formed sediments on the sea floor
what happened once algae had evolved?
they absorbed the CO2 from the oceans to photosynthesise and produce oxygen as a waste product
how are sedimentary rocks formed?
when organisms die, thy sink to the sea bed and are covered in layers of sediment
they then become compressed and form rocks with clear layers
what is coal made from?
compressed plant deposits
what is crude oil made from?
compressed plankton
what is limestone made from?
calcium carbonate deposits from the skeletons of animals
what happened once more plants evolved to photosynthesise?
they absorbed much of the CO2 and released more oxygen into the atmosphere
more complex animals could now evolve
equation for photosynthesis?
carbon dioxide + water -> glucose + oxygen
overall process of the evolving atmosphere
volcanoes produced gases like CO2 and nitrogen oceans were formed green plants started to photosynthesise CO2 was removed and oxygen released more complex animals could now survive
what happens when animals eat plants?
the carbon dioxide in the plant is transferred to the animal’s tissues
how was limestone formed?
animals ingested CO2 through plants
they die
build up of skeletons on seabed
pressure of other sediments forms this sedimentary rocj
how was coal formed?
plant material, such as ferns, was deposited into swamps
they were buried in anaerobic conditions and compressed for millions of years
how were crude oil and natural gas formed?
remains of plankton were deposited into the mud on the seabed
these were covered in sediments
they were compressed
gas and oil are found in this rock
what are the main two ways in which CO2 was removed from the atmosphere?
photosynthesising into plants
dissolving in oceans
how was methane and ammonia removed from the atmosphere?
they reacted with the oxygen
equation for ammonia + oxygen
ammonia + oxygen -> nitrogen and water
equation for methane + oxygen
methane + oxygen -> carbon dioxide and water
what are the main 4 gases in the current atmosphere?
nitrogen
oxygen
argon
carbon dioxide
percentage of nitrogen in atmosphere
78
percentage of oxygen in atmosphere
21
percentage of argon in atmosphere
0.9
percentage of carbon dioxide in atmosphere
0.04
evidence against global warming
natural fluctuations in earth temperature (milankowitch cycles)
one way of measuring the link between CO2 levels and climate
ice cores are drilled from glaciers which have gases (CO2) inside
how does deforestation impact on CO2 levels?
carbon sinks, like rainforests are cut down
less CO2 is removed from air by these trees
CO2 is also released
how do rising ocean temperatures affect CO2 levels?
CO2 is less soluble in warm water
oceans less effective carbon sinks
3 uses of fossil fuels
electricity
heat homes
fuel cars
3 sources of methane
rice fields
cattle
tips
why are methane levels rising? 2
increased cattle farming to feed growing population
more rubbish in landfill sites = more methane released by decomposition of waste
what is peer reviewing?
where other scientists test hypotheses to make sure they are correct
name 3 greenhouse gases
carbon dioxide
methane
water vapour
what is the greenhouse effect?
sun emits short length radiation
this passes through the greenhouse gases in the atmosphere
the earth heats up
it emits infrared radiation to cool down
this is absorbed by the gases
re radiated towards earth and heats it up
