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.
Refraction by an atmosphere (usually Earth's) as a consequence of refractive index gradients resulting from molecular number density gradients arising from pressure, temperature, and possibly water vapor gradients. Near surfaces on the earth (within a few meters or so), atmospheric refraction of visible and near-visible light usually is dominated by temperature gradients. Although atmospheric refraction used without qualification usually means refraction of electromagnetic waves, it could mean refraction of acoustic waves. See mirage.
This is the bending of light the Earth's atmosphere. This causes an increase in the apparent height ( altitude) of an object above the horizon. This increase is zero at the zenith (because the observer is looking out from the Earth at 90 degrees) to about half a degree (the width of the full Moon) at the horizon.
Atmospheric refraction is the deviation of light or other electromagnetic wave from a straight line as it passes through the atmosphere due to the variation in air density as a function of altitude. Atmospheric refraction near the ground produces mirages and can make distant objects appear to shimmer or ripple.