Atmosphere of Earth Atmosphere of Earth The atmosphere of Earth is the layer of gases, commonly known as air, that surrounds the planet Earth and is retained by Earth's gravity. The atmosphere of Earth protects life on Earth by creating pressure allowing for liquid water to exist on the Earth's surface, absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect), and reducing temperature extremes between day and night (the diurnal temperature variation). By volume, dry air contains 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.04% carbon dioxide, and small amounts of other gases. Air also contains a variable amount of water
Trace gas causes its strong absorption of infrared radiation. Below is a table of some of the major greenhouse gases with man-made sources and their contribution to the enhanced greenhouse effect. Key Greenhouse Gases and Sources In contrast, the most abundant gases in the atmosphere are not greenhouse gases. The main reasons is because they cannot absorb infrared radiation as they do not have vibrations with a dipole moment. For instance, the triple bonds of atmospheric dinitrogen make for a highly symmetric molecule that is very inert in the atmosphere. The residence time of a trace gas depends on the abundance and