The Atmosphere

Air and Air Pressure

What is air

Sometimes when people think of “air” the gas that comes to mind is oxygen. Actually, oxygen molecules (O2) are in the minority in our atmosphere. Only 21 percent of Earth’s atmosphere is oxygen, with the majority of it being nitrogen gas (78 percent). The rest is a mixture of argon gas (0.9 percent), 0.035 percent carbon dioxide (CO2), water vapor, and traces of helium, xenon, methane (CH4), nitrous oxide (N2O), neon, and krypton (not to be confused with kryptonite, the stuff that hurts Superman), and a scattering of dust, pollen, and other particulates.


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