C18 Earth's atmosphere Flashcards
Name 3 greenhouse gases
Carbon dioxide
Water vapour
Methane
What is the atmosphere?
A layer of gas surrounding the Earth
What was the Earth’s atmosphere mostly composed of?
CO2
How did the oceans form?
Water vapour condensing as the Earth cooled
How did the amount of CO2 in the atmosphere decrease to todays levels?
-Dissolved in oceans
-Photosynthesis
-Fossil fuels
-Precipitated as insoluble
metal carbonates
When did life start to appear?
2.7 billion years ago
How did the beginning of life impact oxygen in the atmosphere?
Oxygen was more present due to photosynthesis
How has nitrogen in the atmosphere changed over time?
Increased slowly because it is a very stable molecule
Why can scientists not entirely be sure about early Earth’s atmosphere composition?
As evidence is limited and as it was very long ago
What is the current composition of Earth’s atmosphere?
80% nitrogen
20% oxygen
Trace amounts of CO2, water vapour and noble gases
What is a greenhouse gas?
A gas that traps radiation from the sun
What type of radiation do greenhouse gases absorb?
Infrared radiation
2 ways methane levels have increased due to human activity
Rice farming
Cattle farming
2 ways CO2levels have increased due to human activity
Fossil fuels
Deforestation
What is global warming?
Increase in the overall global average temperature