F region

noun

1. the ionospheric region in which the F layer forms.

F region

noun

1. the highest region of the ionosphere, extending from a height of about 150 kilometres to about 1000 kilometres. It contains the highest proportion of free electrons and is the most useful region for long-range radio transmission Also calledAppleton layer See also ionosphere

F region

1. 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 F 1 layer, and the F 2 layer. The F 1 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 F 2 layer. The F 2 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 F 1 layer. It is the main reflecting layer for high frequency communications, both during sunlight hours and during the night.
2. Also called F layer
3. See also ionosphere

Word History and Origins

Origin of F region¹

First recorded in 1925–30