ATMOSPHERIC GASES NEAR THE EARTH'S SURFACE

Permanent
Gases
Chemical
Composition
Percent by VolumeParts per Million
(ppm)
Nitrogen
N2
78.08
780,800
Oxygen
O2
20.95
209,500
Argon
Ar
0.93
9300
Neon
Ne
0.0018
18
Helium
He
0.0005
5
Hydrogen
H2
0.00005
0.5
Xenon
Xe
0.000009
0.09

Variable
Gases
Chemical
Composition
Percent by VolumeParts per Million
(ppm)
Water vapor
H2O
0.001 to 4
10 to 40000
Carbon dioxide
CO2
0.0375
375
Methane
CH4
0.00017
1.7
Nitrous Oxide
N2O
0.00003
0.3
Ozone
O3
0.000004
0.004
CFCs
 
0.00000001
0.0001