T9:Atmosphere

Question 1

What phases were involved in the evolution of the atmosphere?

Answer 1

• Volcanoes gave out gases
• Oceans,algae and green plant plants absorbed carbon dioxide
• Green plants and algae produced oxygen

Question 2

What happened during the first phase?

Answer 2

• First billion years: volcanoes erupt and release gases too make early atm.
• Early mostly CO2, no oxygen. Like Venus/Mars..
• Volcanic activity also released Nitrogen (built up in atm), water vapour , methane and ammonia.

Question 3

What was the early atmosphere like?

Answer 3

-Early mostly CO2, no oxygen. Like Venus/Mars..

Question 4

What happened during the 2nd phase?

Answer 4

• Water vapour condenses=oceans
• Lots of CO22 dissolves in oceans. Then chem.react to form carbonates precipitates that formed sediments on the sea bed.
• Green plants/algae evolve to absorb some of co2 they