The atmosphere is constantly changing because of pollution and global warming.
There are many ways in which the gases in the atmosphere get there. Nitrogen and oxygen get there because of the green plant respiration process and that is also the reason that there is so little...
The atmosphere is made up of approx 79% Nitrogen, 20% Oxygen and 1% Argon and other trace gasses.
nitrogen - 78.084%oxygen - 20.946%argon - 0.934%water vapour - 0.4%carbon dioxide - 0.039%neon - 0.01818%helium - 0.000524%methane - 0.000179%krypton - 0.000114%hydrogen - 0.000055%nitrous oxide -...
nitrogen, oxygen, carbon dioxide, and many others.