ionosphere

noun

A region of the earth’s atmosphere where ionization caused by incoming solar radiation affects the transmission of radio waves. It extends from a height of 70 kilometers (43 miles) to 400 kilometers (250 miles) above the surface.

noun

the outer region of the earth’s atmosphere, beyond which is the exosphere; it contains a high concentration of free electrons and ions, and extends from about 50 miles to about 250 miles above the earth’s surface, but the height shows daily and seasonal variation, and the composition of the particles in the ionosphere is also affected by events such as solar flares.

noun

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.

noun

The similar region of the atmosphere of another planet.

noun

the outer region of the Earth’s atmosphere; contains a high concentration of free electrons