Topic 8b - The Earth's Atmostphere
Gases in the Early Atmostphere
Little or no oxygen
Large amounts of CO2
Water vapour
Small amount of other gases
Evidence
Mixture of gases released by volcanoes
Atmostpheres from other planets
Today's Atmostphere
78% Nitrogen
21% Oxygen
1% Other gases made like argon, water vapour and CO2
Decreasing CO2 and increasing oxygen
Oxygen
As the earth cooled, water vapour condensed and fell as rain forming the oceans
Forms of life evolve in the oceans and photosynthesis begins by algae
Oxygen builds up in the oceans, and carbon dioxide decreased
Oxygen builds up in the atmostphere
CO2
Carbon dioxide dissolved in the oceans forming sediments , and levels fell
Marine orgainsim used it to make calcium carbonat for shells
The shells of dead marine organism fall to the sea bed and become part of the sediment
Over millions of years, the layers of sediment become squashed and form sedimentary rocks
Laboratory test
A glowing splint relights in the presence of oxygen
Limewater turns cloudy in the presence of CO2
A lit splint makes a squeaky pop in the presence of hydrogen
The Greenhouse effect
Reducing radiaiton to space
Greenhouse gases in the atmostphere absorb heat radiated from the Earth
The IR radiation is radiated in all directions, including back to earth
IR radiation is thermal radiation, so it warms the surface of the earth
Greenhouse gases
Carbon Dioxide - burning fossile fuels
Methane - livestock farming
Water Vapour - evapouration from oceans
Global warming and climate change
The accumulation of greenhouse gases in the atmostphere increases the greenouse effect, more IR radiation is absorbed and radiated back to earth
This increase the warming effect in the atmostphere - global warming
Global warming is associated with long term changes to weather patterns - climate change, and rising sea level due to ice caps melting
Green plants and algae absorbed some of the CO2 in the atmostphere
Ozone layer was created which blocks harmful rays from the sun, and enables complex organisms to live
The Sun emits short wavelength radiation which passes through the atmostphere and is re-emitted as long wavelenth radiation (IR) by the earth
Enhanced greenhouse effect
Energy consumption
Since the population has shot up, wev've become more industrialised
Both these factors mean that energy consuption hs increased
We are burning more fossil fuels, releasing more into the atomstphere
Deforestation
We've had to chop down trees to make space for housing
Plants absorb CO2 by photosynthesis
Fewer platns mean less CO2 is being removed from the atmostphere
Farming
Cows prouce large amounts of methane
Crops likes rice do aswell
As the population grows and more food needs to be produced, more methane is produce aswell
Reducing effects of climate change
Cut down on the amount of greenhouse gases we release
Limit fossil fuel use
Walking or cycle instead of taking a car
Using renewable energy
Flood defences can be used to keep homes safe
Intense volcanic activity