Composition of the Earth's atmosphere?

~75% nitrogen. ~25% oxygen. + tiny fraction of other stuff

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  • Nitrogen . . . 78.1%
  • Oxygen . . . 20.9%
  • Argon . . . 0.93%
  • Carbon dioxide . . . 0.04%
  • Neon . . . 0.002%
  • Helium . . . 0.001%


Less than 0.001% :

  • Methane
  • Krypton
  • Hydrogen

Less than 0.0001%
  • Nitrous oxide
  • Carbon monoxide

Less than 0.00001%
  • Xenon
  • Ozone
  • Nitrogen dioxide
  • Iodine
  • Ammonia

Water vapor . . .
  • about 0.4% in the whole atmosphere
  • typically 1% to 4% at the surface