The Earth's atmosphere Flashcards
1
Q
Why is Earth’s atmosphere different to other planet’s?
A
- Not too far or close to the sun
- Can stay at a constant temperature as it looses and gains energy
- 79% nitrogen and 21% oxygen
2
Q
What is the early atmosphere believed to be made up of ?
A
- mainly carbon dioxide with little or no oxygen
small quantities of water vapour ammonia and methane.
3
Q
How did oceans form?
A
The Earth cooled down and the water vapour condensed and formed oceans.
4
Q
How did the proportion of oxygen then increase?
A
This is because of photosynthesis in plants
5
Q
How did the proportion of carbon dioxide increase?
A
- locked up in rocks like limestone
- absorbed by plants for photosynthesis
- dissolved in the oceans
6
Q
What is Earth’s atmosphere made of now?
A
- 79% nitrogen
- 21% oxygen
7
Q
What happened to the excess oxygen?
A
It reacted to the UV light and formed the ozone layer which filters most of the damaging ultra-violet light and allows more complicated life forms to evolve.
8
Q
How was more nitrogen formed.
A
This was because of bacteria in the soil.
