Question

what is the reason for the refraction of light in atmosphere​

Answer 1

The atmosphere of Earth is not evenly distributed, it is optically and molecularly denser at the bottom and and becomes rarer as we up, so the velocity of light changes from layer to layer. The molecules of different gases and dust partcles have different optical densities , moreover the hot air is optically rarer than cold air. These factors form differnt layers of air with different optical densities and thus cause the atmospheric refration.

Answer 2

When the light of a celestial object enters the Earth's atmosphere from space, the resulting refraction is known as astronomical refraction or atmospheric refraction. This is in contrast to terrestrial refraction that occurs when the source of light is from an object on Earth.

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