Question

the sun is seen on the horizon for sometime even after sunset​

Answer 1

Answer:

The reason the sunset seems to be delayed is because of the bending of light waves - emitted by the sun - as they enters the atmosphere, more popularly known as atmospheric refraction.

The atmosphere is nothing but a blanket of air covering the whole surface of the planet. The air is denser near the surface of the planet. Hence when the light waves from the sun are entering the atmosphere they experience a increase in the refractive indices and tend to bend inwards. These bent waves are received by eyes.

The process of refraction also explain why we can see the sun before it has actually appeared above the horizon i.e. an advanced sunset.

The effect of delayed sunset and advance sunrise varies with latitude but is the maximum at the equator.

Answer 2

It is due to the fact that the layers of atmosphere refract and bend the light of sun to a level that it seems that sun has not set and is seen in the horizon.