Definition
Bent from its original straight path as it passes from one medium into another of different density, or through a medium whose density changes. In radio propagation, a sky wave is refracted when it enters the ionosphere and the change in electrical density bends the wave back toward Earth.
Plain English
The wave's path is bent rather than continuing in a straight line. When a radio signal travels upward and hits the ionosphere, it doesn't just keep going into space — its direction is changed, often enough to send it back down to the ground.
Context Anchor
Seen in basic radio principles when explaining sky waves and how some radio signals can travel beyond the normal straight path from the transmitter.
Derivation
From the Latin refractus, meaning 'broken back.' The idea is that the wave's path is 'broken' at the boundary and bent in a new direction — not snapped, but redirected.
Why Pilots Care
Refraction determines how far an HF signal travels and whether it returns to earth for long-range communication beyond line of sight.
Analogy
Like looking at a straw in a glass of water — the straw appears bent at the surface because light is refracted as it passes from water to air. Radio waves do the same thing when they pass through layers of the atmosphere with different properties.
Grounding Statement
Picture a radio wave traveling upward, entering a charged layer high above the Earth, bending, and then returning toward the surface.
Intuition Check
Refracted does not mean the signal simply bounced off a hard surface. It means the signal’s path bent as it passed through a different atmospheric condition.
Example Sentence 1
High-frequency sky waves are refracted by the ionosphere and returned to Earth far beyond the transmitter's line of sight.
Example Sentence 2
Because the signal was refracted rather than absorbed, the pilot maintained contact with the distant station.