Atmosphere Flashcards
Atmosphere of earth today
78% nitrogen
21% oxygen
1% other gases
What makes up the 1% of other gases in the atmosphere?
Water vapour
Carbon dioxide
Noble gases
How long has the atmosphere of today been around?
Around 200 million years
What happened during the first billion years on earth?
Intense volcanic eruptions
That released the gases that form the atmosphere
What gases were released by volcanoes in the first years of the atmosphere?
Water vapour
Carbon dioxide
Nitrogen
Small amounts of Methane and Ammonia
What happened as the earth cooled?
The water vapour released by the volcanoes condensed (became liquid)
And formed oceans
what was the early stage of earths atmosphere like?
Mainly Carbon dioxide
Small amounts of nitrogen
No oxygen
Early atmosphere vs today
Early atmosphere = large amounts of CO2
Todays atmosphere = small amount
Early atmosphere = very little/no oxygen
Today = 21% is oxygen
How did the level of CO2 in the atmosphere change?
CO2 formed seabed
CO2 formed corals and shells for organisms
Plants evolved and so took in CO2
Thus removed CO2 from the atmosphere
How were seabeds formed?
Some CO2 dissolved in oceans form a weak acid
Which reacted with minerals to form PRECIPITATES
Which over time formed sediments of carbon rock on the sea bed
How were corals and limestone formed?
CO2 dissolved in sea
Made corals and shells of organisms such as mussels
When the organisms died they formed rock limestone
How did oxygen enter the atmosphere?
Algae evolved in the oceans that photosynthesised
Plants also evolved photosynthesising more
Fossil fuels
Formed from remains of dead animals and plants over millions of years
Examples of fossil fuels
Coal, oil and gas
What is coal made of?
Formed from ferns and trees
What is crude oil made of?
Formed from plankton
When they die if no oxygen present to break them up
They don’t decompose and are compressed by sediment
High heat and pressure = oil
What is gas made of?
Hydrocarbon methane
Formed near oil because it’s formed in a similar way
Summary of how carbon dioxide left the atmosphere
Dissolved in water to form sea beds and organism shells
After plants evolved:
Got taken in by algae and plants during photosynthesis
Trapped as fossil fuels when these carbon based organisms died but didn’t decompose
Summary of how oxygen entered the atmosphere
Algae evolved and photosynthesised oxygen which eventually evolved other plants which did the same thing
How is coal formed?
If the ferns and trees die in marshy wetlands they don’t decompose
Because there is no oxygen for the decomposers (bacteria) to respire
Or too acidic
So they are covered in sediment then compressed due to high temp and pressure
How is crude oil formed?
When plankton dies they settle on mud on sea bed
No oxygen = no decomposition
So they are compressed by sediment
Causing a high temperature and pressure to convert to crude oil
How is natural gas formed?
Same way as crude oil
By compressing non decomposed plankton
What do fossil fuels contain?
Trapped carbon taken in as carbon dioxide during photosynthesis
By the plankton and ferns it used to be