Question

What is called atmospheric refraction? Which phenomenon results from it?Answer the given question in brief.

Answer 1

 you know that Earth's atmospher has different layers. the densities of these layers decrease as we go higher and higher from the earth's surface. due to difference in their densities, they act as different medium if slightly different refractive indices. so , when a ray of light passes from space ( where ref.index is least) to the earth's atmosphere, it undergoes continues change in ref. index and bends or deviates from its original path giving rise to various phenomenon like twinkling of stars , white colour of the clouds , etc...