| Constituent | Molecular Weight | Content (fraction of total molecules |
|---|---|---|
| Nitrogen(N2) | 28.016 | 0.7808(75.51% by mass) |
| Oxygen(O2) | 32.00 | 0.2095(23.14% by mass) |
| Argon(Ar) | 39.94 | 0.0093(1.28% by mass) |
| Water Vapor(H2O) | 18.02 | 0-0.04 |
| Carbon Dioxide(CO2) | 44.01 | 364 parts per million |
| Neon(Ne) | 20.18 | 18 parts per million |
| Helium(He) | 4.00 | 5 parts per million |
| Krypton(Kr) | 83.7 | 1 parts per million |
| Hydrogen(H) | 2.02 | 0.5 parts per million |
| Ozone(03) | 48.00 | 0-12 parts per million |
Adapted from J. M. Wallace and P. V. Hobbs, 1977:
Atmospheric Science - An Introductory Survey. Academic Press, New York. 467 pp.