ionosphere -
the outer region of the Earth's atmosphere; contains a high concentration of free electrons
region,
part a knowledge domain that you are interested in or are communicating about; "it was a limited realm of discourse"; "here we enter the region of opinion"; "the realm of the occult"
atmosphere,
air the mass of air surrounding the Earth; "there was great heat as the comet entered the atmosphere"; "it was exposed to the air"
d-layer,
d region the lowest region of the ionosphere (35 to 50 miles up) that reflects low-frequency radio waves
ionosphere -
The part of the Earth's atmosphere beginning at an altitude of about 50 kilometers 31 miles and extending outward 500 kilometers 310 miles or more.
ionosphere -
The similar region of the atmosphere of another planet.
Wikipedia
The ionosphere is a portion of the upper atmosphere, between the thermosphere and the exosphere, distinguished because it is ionized by solar radiation. It plays an important part in atmospheric electricity and forms the inner edge of the magnetosphere. It has practical importance because, among other functions, it influences radio propagation to distant places on the Earth.
OmegaWiki Dictionary
Ω
ionosphere A region of the earth's atmosphere, extending from about 60 to 1000 kilometers above the earth's surface, in which there is a high concentration of free electrons and ions formed as a result of ionizing radiation entering the atmosphere from space.
