Composition of "Dry" Air


 

Gas

Symbol

Volume %

Nitrogen

N2

78.084

Oxygen

O2

20.946

Argon

Ar

0.9340

Carbon Dioxide

CO2

0.03697

Neon

Ne

0.00182

Helium

He

0.00052

Methane

CH4

0.00014

Krypton

Kr

0.00010

Ozone

O3

variable

Nitrous oxide

N2O

trace

Hydrogen

H2

trace

Xenon

Xe

trace


from Christopherson (2003)


 

Water vapor, H20, may range from near zero to about 2%.