User:Milton Beychok/Sandbox

Composition of the atmospheric air

Filtered air includes trace amounts of many of the chemical elements. Substantial amounts of argon, nitrogen, and oxygen are present as elementary gases. Note the major greenhouse gases: water vapor, carbon dioxide, methane, nitrous oxide, and ozone. Many additional elements from natural sources may be present in tiny amounts in an unfiltered air sample, including contributions from dust, pollen and spores, sea spray, vulcanism, and meteoroids. Various industrial pollutants are also now present in the air, such as chlorine (elementary or in compounds), fluorine (in compounds), elementary mercury, and sulfur (in compounds such as sulfur dioxide (SO₂)).

Composition of Dry Air

Gas		Concentration
Name	Symbol	Volume %	ppmv
Nitrogen	N2	78.084	780,840
Oxygen	O2	20.947	209,470
Argon	Ar	0.934	9,340
Carbon dioxide	CO2	0.033	330
Neon	Ne	0.001820	18.20
Helium	He	0.000520	5.20
Methane	CH4	0.000200	2.00
Krypton	Kr	0.000110	1.10
Sulfur dioxide	SO2	0.000100	1.00
Hydrogen	H2	0.000050	0.50
Nitrous oxide	N2O	0.000050	0.50
Xenon	Xe	0.000009	0.09
Ozone	O3	0.000007	0.07
Nitrogen dioxide	NO2	0.000002	0.02