Topic 10 Flashcards
What formed the early earths atmosphere?
Gases produced by volcanic activity
What do scientists believe about the earths eskryxatomsphere billions of years ago contained:
Little or no oxygen
A large amount of carbon dioxide
Water vapour
Small amounts of other gases
EVIDENCE
mixture of gases released by volcanoes
Atmosphere of other planets in our solar system today which have not been changed by living organisms
Today’s atmosphere
Nitrogen and oxygen are the main gases in the modern atsmisohere
Ntrogen 78%
Oxygen 21%!
Other gases including argon water vapour sndncarbon dioxide 1%
The earth was very hot to start with as it cooled,
Water vapour condensed and fellnas rain to form the oceans
Earth cools and oceans forms …
Forms of life evolve in the oceans and photosynthesis begins
Oxygen builds up in the oceans
Oxygen builds up in the atmosphere
Carbon dioxide dissolved in the oceans …
Marine organisms used the dissolved carbon dioxide to make calcium carbonate for shells
The shells of dead Marin organisms fall to the sea bed and become part of the sediment
Over millions of years the layers is sediment become squashed and form sedimentary rocks
Some rocks contain iron
Very old rocks do not contain iron oxides but later ones do
Explain how these rocks provide evidence for changes o the earths atmosphere
The very old rocks are evidence that the early atmosphere contained little or no oxygen because they do not contain iron oxides
Later rocks do contain iron oxides which is evidence rhatxoxygen was released into the atmosphere and reacted with iron in the rocks
When oxygen was first produced it reacted with iron in rocks to produce
Iron oxides
This meant that even though primitive plants were photosynthesising oxygen levels in the atmosphere did not begin to rise straight away
State how the formation of oceans was a cause of decreasing carbon dioxide levels
Carbon dioxide dissolved in the oceans
Describe why the levels of oxygen in the atmosphere increased
Plants produced oxygen by photosynthesis
Suggest a reason that explains why scientists cannot be certain about the earths early atmosphere
No measurements were made then/no humans were on earth then
What does the greenhouse effect do
Helps to keep the earth warm enough for living organisms to exist
What happens in the greenhouse effect
Greenhouse gases in the atmosphere absorb heat radiated from the earth
The greenhouse gases then release energy in all directions
This reduces the amount of heat radiated into space keeping the earth warm
What types of greenhouse gases are particularly good at absorbing and emitting energy by radiation
Carbon dioxide -> burning fossil fuels
Methane -> livestock farming
Water vapour -> evaporation form oceans
The accumulation of greenhouse gases in the atmosphere :
Increased the greenhouse effect which then
Increases the warming effect in the atmosphere - global warming
Global warming is associated with
Long term changes to weather patterns - climate change
Rising sea levels due to melting ice and expanding ocean water
Describe how the greenhouse effect keeps the earth warm
Greenhouse gases absorb heat radiated from the earth thebgases then release the heat into the atmosphere
Explain how the increased use of fossil fuels which contain carbon and carbon compounds may lead to global warming
Fossil fuels give off carbon dioxide during combustion
Increased consumption releases more carbon dioxide
Which is a greenhouse gas
Socyhe greenhousebeffect increases
Flame test for lithium
Red
Sodium
Yellow
