F layer

[ ef ley-er ]

noun

, Physics.

1. the highest of the radio-reflective layers of the ionosphere, beginning at an altitude of about 80 miles (130 km) and consisting of two parts, the lower part F1 layer being detectable in the daytime only, the higher F2 layer, or Appleton layer being constant and constituting the ionospheric layer most favorable for long-range radio communication.

F layer

1. See F region

Word History and Origins

Origin of F layer¹

First recorded in 1925–30