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Atmosphere
This article is about the general term "atmosphere". For specific information about the Earth's atmosphere, see Atmosphere of Earth.
For other uses, see Atmosphere (disambiguation)
View of Jupiter's active atmosphere, including the Great Red Spot.
An atmosphere (New Latin atmosphaera, created in the 17th century from Greek ἀτμός [atmos] "vapor"[1] and σφαῖρα [sphaira] "sphere"[2]) is a layer ofgases surrounding a planet or other material body of sufficient mass[3] that is held in place by the gravity of the body. An atmosphere is more likely to be retained if the gravity is high and the atmosphere's temperature is low.
Earth's atmosphere, which contains oxygen used by most organisms for respiration and carbon dioxide used by plants, algae and cyanobacteria forphotosynthesis, also protects living organisms from genetic damage by solar ultraviolet radiation. Its current composition is the product of billions of years of biochemical modification of the paleoatmosphere by living organisms.
The term stellar atmosphere describes the outer region of a star, and typically includes the portion starting from the opaque photosphere outwards. Stars with sufficiently low temperatures may form compound molecules in their outer atmosphere.
Atmospheric pressure is the force per unit area that is always applied perpendicularly to a surface by the surrounding gas. It is determined by a planet's gravitational force in combination with the total mass of a column of gas above a location. On Earth, units of air pressure are based on the internationally recognized standard atmosphere (atm), which is defined as 101,325 Pa (or 1,013,250 dynes per cm2). One (atm) equals 14.696 pounds per square inch (psi).
The pressure of an atmospheric gas decreases with altitude due to the diminishing mass of gas above each location. The height at which the pressure from an atmosphere declines by a factor of e(an irrational number with a value of 2.71828..) is called the scale height
This article is about the general term "atmosphere". For specific information about the Earth's atmosphere, see Atmosphere of Earth.
For other uses, see Atmosphere (disambiguation)
View of Jupiter's active atmosphere, including the Great Red Spot.
An atmosphere (New Latin atmosphaera, created in the 17th century from Greek ἀτμός [atmos] "vapor"[1] and σφαῖρα [sphaira] "sphere"[2]) is a layer ofgases surrounding a planet or other material body of sufficient mass[3] that is held in place by the gravity of the body. An atmosphere is more likely to be retained if the gravity is high and the atmosphere's temperature is low.
Earth's atmosphere, which contains oxygen used by most organisms for respiration and carbon dioxide used by plants, algae and cyanobacteria forphotosynthesis, also protects living organisms from genetic damage by solar ultraviolet radiation. Its current composition is the product of billions of years of biochemical modification of the paleoatmosphere by living organisms.
The term stellar atmosphere describes the outer region of a star, and typically includes the portion starting from the opaque photosphere outwards. Stars with sufficiently low temperatures may form compound molecules in their outer atmosphere.
Atmospheric pressure is the force per unit area that is always applied perpendicularly to a surface by the surrounding gas. It is determined by a planet's gravitational force in combination with the total mass of a column of gas above a location. On Earth, units of air pressure are based on the internationally recognized standard atmosphere (atm), which is defined as 101,325 Pa (or 1,013,250 dynes per cm2). One (atm) equals 14.696 pounds per square inch (psi).
The pressure of an atmospheric gas decreases with altitude due to the diminishing mass of gas above each location. The height at which the pressure from an atmosphere declines by a factor of e(an irrational number with a value of 2.71828..) is called the scale height