The sun near the horizon appears flattened at sunset and sunrise. Explain why.

Explanation

At sunrise and sunset, the rays from the sun travel a larger distance in the earth.s atmosphere to reach the eyes of the observer. Due to a decrease in density and refractive index in the atmosphere, with increasing altitude these rays undergo refraction [atmospheric refractio]. So, the rays from the top and bottom portion of the sun near the horizon are refracted by different degrees. But the rays from the middle portion of the sun are refracted by the same amount. This causes the apparent flattering the sun.s disc at the top and bottom but it remains curved at the middle.