Atmosphere Definition

The gaseous mass or envelope surrounding a celestial body, especially the one surrounding the earth, and retained by the celestial body's gravitational field.
American Heritage
The gaseous envelope (air) surrounding the earth to a height of c. 1,000 km (c. 621 mi): it is c. 21% oxygen, 78% nitrogen, and 1% other gases, and rotates with the earth, because of gravity.
Webster's New World
The air or climate in a specific place.
American Heritage
The gaseous mass surrounding any star, planet, etc.
Webster's New World
A unit of pressure equal to the air pressure at sea level. It equals the amount of pressure that will support a column of mercury 760 millimeters high at 0 degrees Celsius under standard gravity, or 14.7 pounds per square inch (1.01325 × 105 pascals).
American Heritage
The mixture of gases surrounding the Earth or other celestial body, held in place by gravity. It forms distinct layers at different heights. The Earth's atmosphere consists, in ascending order, of the troposphere (containing 90% of the atmosphere's mass), the stratosphere, the mesosphere, the thermosphere, and the exosphere. The atmosphere is composed primarily of nitrogen (78%) and oxygen (21%) and plays a major role in the water cycle , the nitrogen cycle , and the carbon cycle .
American Heritage Science
A unit of pressure equal to the pressure of the air at sea level, about 14.7 pounds per square inch, or 1,013 millibars.
American Heritage Science

The mixture of gases that surrounds and is retained by the gravity of a celestial body such as the Earth.The atmosphere is denser near the Earths surface, and becomes gradually thinner until it fades away into space. Particularly near the Earths surface, the physical matter in the atmosphere attenuates electromagnetic signals due to absorption, refraction and other phenomena. At the outer limits of the atmosphere are four layers of the ionosphere, which is useful for skywave radio propagation. See also attenuation, ionosphere, propagation, refraction, and skywave.

Webster's New World Telecom

Other Word Forms of Atmosphere



Origin of Atmosphere

  • From New Latin atmosphaera, from Ancient Greek ἀτμός (atmós, “steam”) + Ancient Greek σφαῖρα (sphaĩra, “sphere”); corresponding to atmo- +‎ -sphere (?).

    From Wiktionary

  • New Latin atmosphaera Greek atmos vapor wet-1 in Indo-European roots Latin sphaera sphere sphere

    From American Heritage Dictionary of the English Language, 5th Edition


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