The Earth's Sea and Atmosphere Flashcards
What is the atmosphere?
An envelope of different gases (air) surrounding Earth
Why is Earth different to other planets in our solar system?
It has an atmosphere that can support life
What is the composition of today’s atmosphere?
Nitrogen: 78% Oxygen: 21% 1% other gases:- Argon: 0.93% Carbon dioxide: 0.035% Varying amounts of water vapour Trace amounts of other gases
How has the atmosphere changed from 4.5 billion to today?
At first there was no atmosphere
Then the surface cooled and formed a solid crust
Volcanoes formed and released Carbon Dioxide, Methane, Steam and Ammonia
The Earth cooled even more and the steam condensed to form the oceans
Trees and animals evolved
What did the early atmosphere contain?
Little or no oxygen
A large amount of carbon dioxide
Water vapour and a small amount of other gases
How can you figure out the amount of oxygen in the atmosphere?
By oxidising copper.
Move 100cm^3 of air over copper while heating it. Only the oxygen will react with the copper, so the amount of air left will have no oxygen.
Therefore 100 minus the amount of air left will give you the oxygen content of air.
How were cyanobacteria and stromatolites useful in the development of the atmosphere?
They were the first organisms to photosynthesise, which created oxygen, allowing other organisms to develop
What is the chemical formula for ozone?
O3
Where is the ozone layer found?
In the stratosphere
Why was the ozone layer important in the development of the atmosphere?
It blocks harmful radiation from the sun which can damage and kill life on Earth
Why did the amount of ammonia in the atmosphere go down?
It reacted with oxygen in the atmosphere to form nitrogen and water:
4NH3 + 3O2 —-> 2N2 + 6H2O
What were iron bands?
Iron bands were made of iron oxide or rust. The iron came from volcanic activity in the oceans and the oxygen came from stromatolites photosynthesising. They prevented the oxygen level from rising for a few billion years because they were using up the oxygen being produced. They eventually went away because there was so much life producing oxygen the iron was deposited where it formed.
What is the global average temperature and what would it be without the greenhouse effect?
It is 13 degrees Centigrade, compared to -22 degrees Centigrade without the greenhouse effect.
What are the stages of the greenhouse effect?
Stage 1: Radiation from the Sun in the form of light waves enters the atmosphere and warms the Earth
Stage 2: Infrared radiation is produced by the Earth. Some of this heat travels through the atmosphere and escapes into space
Stage 3: Some of this heat is absorbed by greenhouse gases in the atmosphere and so is reflected back to Earth. This causes the temperature of the Earth to rise
Stage 4: Increased levels of greenhouse gases in the atmosphere trap more of the emitted heat. This leads to a greater increase in hte Earth’s temperature
What are the three main greenhouse gases?
Water vapour, methane and sulphur dioxide
