The composition of the atmosphere (excluding water vapor) below 80 kilometers is about 78 percent nitrogen and 21 percent oxygen by volume (76 percent nitrogen, 23 percent oxygen by mass). The remaining 1 percent includes all other dry gases, chiefly argon, carbon dioxide, neon, helium, krypton, hydrogen, and ozone. Water vapor, the most variable constituent of the atmosphere, typically occupies between 0 percent and 4 percent of the atmospheric volume. This mixture of gases is commonly... więcej

Salem Press Encyclopedia of Science, 2023. 3p.