Definitions for "Atmospheric refraction"
The refraction of light entering the Earth's atmosphere from the near-vacuum of space; it is best toward the zenith.
The change in direction of a ray of light as it passes from space into the atmosphere. This causes celestial objects to appear to be in a location different from their actual ones.
as light from the sun (or another celestial body) travels from the vacuum of space into Earth's atmosphere, the path of the light is bent due to refraction. This causes stars and planets near the horizon to appear higher in the sky than they actually are, and explains how the sun can still be visible after it has physically passed beyond the horizon at sunset. See also apparent sunrise. Click here for a graph of atmospheric refraction vs. elevation.