ionosphere

American  

[ahy-on-uh-sfeer] / aɪˈɒn əˌsfɪər /

noun

1. 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.

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ionosphere British  

/ aɪˈɒnəˌsfɪə, aɪˌɒnəˈsfɛrɪk /

noun

1. 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

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ionosphere Scientific  

/ ī-ŏn′ə-sfîr′ /

1. 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.

2. See more at D region E region F region

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ionosphere Cultural  

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

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Discover More

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.

Other Word Forms

• ionospheric
  adjective

Etymology

Origin of ionosphere

First recorded in 1925–30; iono- + -sphere

Example Sentences

See Examples For:

ionosphere

When solar activity surges, electron density in the ionosphere can rise significantly.

From Science Daily ● Feb. 24, 2026

As the storm weakened, the plasmasphere began to replenish with particles supplied by the ionosphere.

From Science Daily ● Nov. 23, 2025

The satellites will map the magnetic fields, upper atmosphere and ionosphere of Mars in 3D, gathering data that will help humans land or even settle on the Red Planet.

From MarketWatch ● Nov. 7, 2025

The vortex spins fastest in the ionosphere, progressively weakening as it reaches each deeper layer.

From Science Daily ● Nov. 26, 2024

The massive disturbances to the ionosphere would knock out communications systems everywhere, so survivors would have no idea what was happening elsewhere or where to turn.

From "A Short History of Nearly Everything" by Bill Bryson