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[ahy-on-uh-sfeer] /aɪˈɒn əˌsfɪər/
the region of the earth's atmosphere between the stratosphere and the exosphere, consisting of several ionized layers and extending from about 50 to 250 miles (80 to 400 km) above the surface of the earth.
Origin of ionosphere
1925-30; iono- + -sphere
Related forms
[ahy-on-uh-sfer-ik] /aɪˌɒn əˈsfɛr ɪk/ (Show IPA),
adjective Unabridged
Based on the Random House Dictionary, © Random House, Inc. 2015.
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Examples from the Web for ionosphere
Historical Examples
  • Extensive reports on the condition 176 of the ionosphere poured into headquarters.

  • Then we were able to modify that to heave sand and to let it tap the ionosphere.

    Sand Doom William Fitzgerald Jenkins
  • The ionosphere of Eisberg was much deeper and, although the intensity was less, the duration was much longer.

    Unwise Child Gordon Randall Garrett
  • They struck the Earth's ionosphere, and their numbers diminished.

    Out Like a Light Gordon Randall Garrett
  • Without the landing grid and the power it took from the ionosphere, they could not receive supplies from the rest of the universe.

    Sand Doom William Fitzgerald Jenkins
  • It was not the intensity of the ionosphere that cracked the drive of the Brainchild; it was the duration.

    Unwise Child Gordon Randall Garrett
British Dictionary definitions for ionosphere


a region of the earth's atmosphere, extending from about 60 kilometres to 1000 km above the earth's surface, in which there is a high concentration of free electrons formed as a result of ionizing radiation entering the atmosphere from space See also D region, E region, F region
Derived Forms
ionospheric (aɪˌɒnəˈsfɛrɪk) adjective
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for ionosphere

1926, from ion + sphere. Coined by Scottish radar pioneer Robert A. Watson-Watt (1892-1973). So called because it contains many ions.

Online Etymology Dictionary, © 2010 Douglas Harper
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ionosphere in Science
A region of the Earth's upper atmosphere, extending from a height of 70 km (43 mi) to 400 km (248 mi) and containing atoms that have been ionized by radiation from the Sun. The ionosphere lies mostly in the lower thermosphere and is subdivided into three regions, the D region (70 km to 90 km; 43 to 56 mi), the E region (90 km to 150 km; 56 to 93 mi), and the F region (150 km to 400 km; 93 to 248 mi). The concentration of ionized atoms is lowest in the D region, intermediate in the E region, and highest in the F region. The ionosphere is useful for radio transmission because radio waves, which normally propagate in straight lines, are reflected off the ionized gas particles, thereby being transmitted long distances across the Earth's curved surface. See more at D region, E region, F region.

The American Heritage® Science Dictionary
Copyright © 2002. Published by Houghton Mifflin. All rights reserved.
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ionosphere in Culture
ionosphere [(eye-on-uh-sfeer)]

A region of the atmosphere that begins at an altitude of about thirty miles.

Note: In this region, free particles carrying an electrical charge, atoms ionized (see ionization) by radiation from the sun, reflect radio waves. “Bouncing” radio waves off the ionosphere makes communication possible over long distances of the surface of the Earth.
The American Heritage® New Dictionary of Cultural Literacy, Third Edition
Copyright © 2005 by Houghton Mifflin Company.
Published by Houghton Mifflin Company. All rights reserved.
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