Atmospheric refraction refers to the bending of light as it passes through Earth's atmosphere. This causes the light to deviate from its straight path, making objects appear higher and distorted, especially near the horizon.
Full definition
• This effect is caused
by atmospheric refraction, the same type that makes the sun appear to rise earlier and set later than would be expected from astronomical calculations.
«By the time the apparent sun (that is, the sun as we see it in the sky) just starts to set, the actual sun (as we would see it if there were
no atmospheric refraction) has completely set.