The atmosphere contain the following gasses:
Carbon Dioxide: 0.03%
And a small trace of other gases.
Water (in the form of vapor, droplets and ice crystals) is the next most common thing. There are also small amounts of other gases, plus many small solid particles, like dust, soot and ashes, pollen, and salt from the oceans.
Water Vapor: There is much more water vapor than carbon dioxide in the atmosphere. Water vapor changes from a trace in extremely cold and dry air to about 4% in extremely warm and humid air. The average amount of water vapor in the atmosphere averaged for all locations is between 2 and 3%.
Methane: Methane is an important trace gas in Earth’s atmosphere. Even though it only makes up 0.00017% of the atmosphere, methane traps a significant amount of heat, helping the planet remain warm and habitable.
Nitrous Oxides: On a global basis, it is estimated that natural sources account for over 60% of the total N2O emissions. Nitrogen oxides are produced in combustion processes, partly from nitrogen compounds in the fuel, but mostly by direct combination of atmospheric oxygen and nitrogen in flames. Nitrogen oxides are produced naturally by lightning.