Question

why does sun appear 2 minutes early in morning? why not 2 minutes delay like evening?

Answer 1

Dear Student
Advancement in sunrise is due to atmospheric refraction.
When the Sun is slightly below the horizon, the light coming from it travels from less dense to more dense air and is refracted downwards. So image formed is above horizon Thus, the Sun appears to be raised and can be seen 2 min before actual sunrise. Same is case when sunsets.So when sun sets and goes below horizon, after then also we can see sun for some time as image formed is above horizon due to atmospheric refraction.
So, at time of sun rise Sun appears to come early above horizon and at time of sun sets sun appear to go late below horizon.

Regards