ionosphere

noun

ion·​o·​sphere ī-ˈä-nə-ˌsfir 

: 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)

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

Sato said that atmospheric waves, including gravity waves and global-scale tidal waves, affect the ionospheric dynamo, a process generating an electrical current around the planet through the interaction between Earth's magnetic field lines and the motions of the ionized air of the ionosphere. —Tereza Pultarova, Space.com, 21 Jan. 2025

Read more Space Weather Radio Blackouts Anticipated As Sunspot Turns Towards Earth How and When To See the Northern Lights: The Best Way To Find Auroras Solar flares cause radio blackouts at frequencies below 30 MHz due to them ionizing the Earth's ionosphere. —Thomas G. Moukawsher, Newsweek, 6 Nov. 2024

The researchers suggest that these white lights arise due to a combination of heating in the ionosphere due to the surrounding aurora, as well as the chemiluminescence of some other gases in the atmosphere, possibly nitrogen dioxide. —Yaakov Katz, Newsweek, 13 Jan. 2025

However, even though these reactions were confirmed to create various ions, such O+, O2+, and CO2+ in the Martian ionosphere, there is still no evidence to say O2 is formed this way. —Victoria Corless, Space.com, 2 Jan. 2025

Word History

Etymology

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The term was introduced by the British engineer and physicist Robert A. Watson-Watt (1892-1973), apparently first in an unpublished letter (November 8, 1926) to the secretary of the Radio Research Board, a government agency (see Nature, vol. 224, December 13, 1969, p. 1096).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.

First Known Use

1926, in the meaning defined above

Kids Definition

ionosphere

noun

ion·​o·​sphere ī-ˈän-ə-ˌsfi(ə)r 

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

ionospheric

ī-ˌän-ə-ˈsfi(ə)r-ik 

-ˈsfer-

adjective