F layer

An ionized layer in the F region of the ionosphere which consists of the Fi and F2 layers in the day hemisphere, and the F2 layer alone in the night hemisphere; it is capable of reflecting radio waves to earth at frequencies up to about 50 megahertz.

Related terms:

• E layer
• D layer
• layer
• F1 layer
• earth-layer propagation
• low-velocity layer
• surface boundary layer
• critical frequency
• F2 layer
• shielding layer