F region

F region

n.

See F layer.

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F region

The highest region of the ionosphere, consisting of free electrons generated by the ionizing effect of solar radiation. This region is subdivided into two layers, designated the F₁ layer, and the F₂ layer. The F₁ layer extends from about 150 km (93 mi) to 240 km (149 mi) above the surface of the Earth and exists only during sunlight hours. At night it merges into the F₂ layer. The F₂ layer extends from about 240 km (149 mi) to 400 km (248 mi). The density of free electrons in this layer is much higher than it is in the F₁ layer. It is the main reflecting layer for high frequency communications, both during sunlight hours and during the night. Also called F layer. See also ionosphere.

Thesaurus

Noun

1.

F region - the highest region of the ionosphere (from 90 to 600 miles up) which contains the highest concentration of free electrons and is most useful for long-range radio transmission Appleton layer, F layer ionosphere - the outer region of the Earth's atmosphere; contains a high concentration of free electrons