The Earth's atmosphere is a mixture of gases, with the following approximate composition by volume:

* Nitrogen (N2): 78.084%

* Oxygen (O2): 20.946%

* Argon (Ar): 0.934%

* Carbon dioxide (CO2): 0.041%

Other gases present in trace amounts include:

* Neon (Ne)

* Helium (He)

* Methane (CH4)

* Krypton (Kr)

* Hydrogen (H2)

* Nitrous oxide (N2O)

* Ozone (O3)

* Xenon (Xe)

Variable components:

* Water vapor (H2O): This varies significantly depending on location and weather conditions.

* Aerosols: These are tiny particles suspended in the air, including dust, smoke, pollen, and sea salt.

Note: The composition of the atmosphere can vary slightly depending on altitude and location.