The three major constituents of Earth's atmosphere are nitrogen, oxygen, and argon. Water vapor accounts for roughly 0.25% of the atmosphere by mass. The concentration of … See more

Pressure and thickness
The average atmospheric pressure at sea level is defined by the International Standard Atmosphere as … See more

Earliest atmosphere
The first atmosphere, during the Early Earth's Hadean eon, consisted of gases in the solar nebula, primarily hydrogen. There were probably simple See more

In general, air pressure and density decrease with altitude in the atmosphere. However, the temperature has a more complicated profile … See more

Solar radiation (or sunlight) is the energy Earth receives from the Sun. Earth also emits radiation back into space, but at longer wavelengths … See more

Atmospheric circulation is the large-scale movement of air through the troposphere, and the means (with ocean circulation) by which heat is … See more

Air pollution is the introduction of airborne chemicals, particulate matter or biological materials that cause harm or discomfort to organisms. The See more