20.95 % of oxygen is in the earth's atmosphere.
20.95 % of oxygen is in the earth's atmosphere.
how much oxygen is in the earth's atmosphere?
20.95 %
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.
atmosphere of earth
the amount of oxygen in the atmosphere has fluctuated over the last 600 million years, reaching a peak of about 30% around 280 million years ago, significantly higher than today's 21%. two main processes govern changes in the atmosphere: plants use carbon dioxide from the atmosphere, releasing oxygen. breakdown of pyrite and volcanic eruptions release sulfur into the atmosphere, which oxidizes and hence reduces the amount of oxygen in the atmosphere. however, volcanic eruptions also release carbon dioxide, which plants can convert to oxygen. the exact cause of the variation of the amount of oxygen in the atmosphere is not known. periods with much oxygen in the atmosphere are associated with rapid development of animals. today's atmosphere contains 21% oxygen, which is great enough for this rapid development of animals.
atmosphere of earth