ion·​o·​sphere | \ī-ˈä-nə-ˌsfir \

Definition of ionosphere 

: the part of the earth's atmosphere in which ionization of atmospheric gases affects the propagation of radio waves, which extends from about 30 miles (50 kilometers) to the exosphere, and which is contiguous with the upper portion of the mesosphere and the thermosphere also : a comparable region of charged particles surrounding another celestial body (such as Venus)

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Other Words from ionosphere

ionospheric \ ˌī-​ˌä-​nə-​ˈsfir-​ik , -​ˈsfer-​ \ adjective
ionospherically \ ˌī-​ˌä-​nə-​ˈsfir-​i-​k(ə-​)lē , -​ˈsfer-​ \ adverb

Examples of ionosphere in a Sentence

Recent Examples on the Web

The ionosphere is where high-energy cosmic rays collide with our atmosphere and the Northern Lights appear. Avery Thompson, Popular Mechanics, "A Group of Scientists Want to Launch a Satellite to Make an Artificial Aurora," 29 Oct. 2018 Many of those ions accumulate in (surprise!) the ionosphere. Diana Gitig, Ars Technica, "Oxygen ions may be an easy-to-track sign of life on exoplanets," 16 Feb. 2018 As a result of this launch profile, the rocket maintained a nearly vertical trajectory all the way through much of the Earth's ionosphere, which ranges from about 60km above the planet to 1,000km up. Eric Berger, Ars Technica, "SpaceX launch last year punched huge, temporary hole in the ionosphere," 22 Mar. 2018 The rocket launch also punched a temporary, 900-km-wide hole into the plasma of the ionosphere. Eric Berger, Ars Technica, "SpaceX launch last year punched huge, temporary hole in the ionosphere," 22 Mar. 2018 The site’s phased array radar bounces energy off the ionosphere to scan for objects beyond the line of sight, well over the horizon. Joe Pappalardo, Popular Mechanics, "What Putin Would Nuke," 5 Mar. 2018 Those same energetic specks flood the ionosphere, sometimes disabling the stable layer off which high-frequency radio signals bounce. Ned Rozell, Anchorage Daily News, "Space weather: Havoc caused by the sun," 17 Feb. 2018 But little is known about this boundary zone, called the ionosphere, which begins about 60 miles above Earth. Alex Stuckey, San Antonio Express-News, "New NASA mission to study little-known boundary between Earth and outer space," 5 Jan. 2018 These rings affect the way the ionosphere is charged, researchers report today in Science. Andrew Wagner, Science | AAAS, "Watch rain and shadows from Saturn’s rings give the planet a funky ionosphere," 11 Dec. 2017

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'ionosphere.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of ionosphere

1926, in the meaning defined above

History and Etymology for ionosphere

ion or ion(ization) + -o- + -sphere

Note: The term was introduced by the British engineer and physicist Robert A. Watson-Watt (1892-1973), apparently first in an unpublished letter (November 8, 1926) to the secretary of the Radio Research Board, a government agency (see Nature, vol. 224, December 13, 1969, p. 1096). Watson-Watt used it in print in the Quarterly Journal of the Royal Meteorological Society, vol. 55 (1929), p. 278.

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Last Updated

13 Nov 2018

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Time Traveler for ionosphere

The first known use of ionosphere was in 1926

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More Definitions for ionosphere


ion·​o·​sphere | \ī-ˈä-nə-ˌsfir \

Kids Definition of ionosphere

: the part of the earth's atmosphere beginning at an altitude of about 30 miles (50 kilometers) and extending outward that contains electrically charged particles

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