Forms: Also 16 -sphære, -sphear.
Etymology: < modern Latin atmosphæra, < Greek ἀτμός vapour + σϕαῖρα ball, sphere.
a. The spheroidal gaseous envelope surrounding any of the heavenly bodies.
1638 Bp. J. Wilkins Discov. World in Moone x. 138 There is an Atmo-sphæra, or an orbe of grosse vaporous aire, immediately encompassing the body of the Moone.
1693 R. Bentley Boyle Lect. vii. 13 The Sun and Planets and their Atmospheres.
1881 Stokes in Nature No. 625. 597 In the solar atmosphere there is a cooling from above.
b. esp. The mass of aeriform fluid surrounding the earth; the whole body of terrestrial air.The name was invented for the ring or orb of vapour or ‘vaporous air’ supposed to be exhaled from the body of a planet, and so to be part of it, which the air itself was not considered to be; it was extended to the portion of surrounding air occupied by this, or supposed to be in any way ‘within the sphere of the activity’ of the planet (Phillips 1696); and finally, with the progress of science, to the supposed limited aeriform environment of the earth or other planetary or stellar body. (It is curious that the first mention of an atmosphere is in connection with the Moon, now believed to have none.)
1677 R. Plot Nat. Hist. Oxford-shire 4 That subtile Body that immediately incompasses the Earth, and is filled with all manner of exhalations, and from thence commonly known by the name of the Atmosphere.
1728 E. Chambers Cycl. (at cited word), Among the more accurate Writers, the Atmosphere is restrain’d to that Part of the Air next the Earth, which receives Vapours and Exhalations; and is terminated by the Refraction of the Sun’s Light.
1867 E. B. Denison Astron. without Math. 56 The earth’s atmosphere decreases so rapidly in density, that half its mass is within 3½ miles above the sea; and at 80 miles high there can be practically no atmosphere.
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