| A | B |
|---|
| atmosphere | Mixture of gas surrounding the earth |
| Nitrogen | Most abundant gasin atmos. |
| Oxygen | Second most abundant gas in atmos |
| Homosphere | Evenly mixed layer 1 |
| Heterosphere | Gases stratified according to weight |
| Water vapor | Third largest component of near surface gases |
| Ionosphere | Gases exist in their ionized state |
| Argon | Third most abundant elemental gas |
| Carbon Dioxide | Fourth most abudant in air w/o water |
