Atmosphere Flashcards
what is the atmosphere
a layer of gas surrounding the earth
what was the early atmosphere composed of
mostly co2
how did the oceans form
water vapour condensed as the earth cooled
how did the amount of co2 in the atmosphere decrease to todays level
dissolved in oceans, photosynthesis, covered to fossil fuels, precipitated as insoluble metal carbonates
when did life start to appear and what was the impact of this on oxygen in the atmosphere
2.7 billion years ago, amount of oxygen increased as it was released in photosynthesis
how has the amount of nitrogen in the atmosphere changed overtime
increased slowly as its a very stable molecule
why can scientists not be sure about the composition of the earths early atmosphere
it was billions of years ago and evidence is limited
what is the current composition of the 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
longer wavelength infrared radiation
name 3 greenhouse gases
methane, co2, water vapour
give 2 ways recent human activities have increased atmospheric co2
burning fossil fuels and cattle farming
what is global warming
an increase in the overall global average temp
what is global climate change
the change in long term weather patterns across the planet
what are some possible effects of climate change
sea levels rising, extreme weather events, changes to ecosystems and habitats, ice caps melting
