topic 4 - earth and atmosphere Flashcards
What formed the earths early atmosphere
Gases produced by volcanic activity (water vapour, CO2, CH4, and small amounts of others)
How much O2 did the early atmosphere contain?
Virtually none
What was the early atmosphere composed of?
Majority - CO2
Small* - Nitrogen
*but increasing
What is today’s atmosphere composed of?
78% - Nitrogen
21% - Oxygen
0.04% - Carbon Dioxide
What were the oceans formed from?
Water vapour from volcanoes condensed and formed oceans.
Why did the amount of CO2 in the atmosphere decrease when oceans were formed?
CO2 dissolved into the oceans
How did the growth of primitive plants change the atmosphere’s composition?
When green (photosynthesising) plants evolved, gradually CO2 was removed from the air and replaced by O2
Describe the chemical test for oxygen
Oxygen will relight a glowing splint.
- Hold a glowing splint near an open tube filled with the substance, if O2 is present it will relight
What is the green house effect (natural process)?
When greenhouse gases in the atmosphere absorb long wavelength radiation and re-radiate it in all directions, including back towards earth, helping to keep the earth warm
What gases contribute to the greenhouse effect?
Carbon dioxide, methane, water vapour
What is the evidence for human activity causing climate change?
Increased population means more greenhouse gases because more:
- fossil fuels burnt - (for energy) more CO2 released
- deforestation - less CO2 removed by photosynthesis
- farming - more methane produced
2 possible consequences of climate change:
- Flooding due to the melting of the polar ice caps causing sea levels to rise
- Changing rainfall pattern (extreme weather)
how can effects on the climate may be mitigated (individuals)
- Walk/cycle instead of driving
- turn down central heating
how effects on the climate may be mitigated (governments)
- use legislation and financial incentives
- fund research into new energy sources
