Question

Explain advanced sunrise and delayed sunset.......

Answer 1

And due to this sun appears to be raised above the horizon and so rising can be seen before 2 mins.... Same phenomenon applies for delayed setting of sun

Answer 2

the sun becomes rarer as it's height above the earth increases . It's refractive index decrease. A ray of light from the sun when enters the atmosphere at the horizon get refracted from rarer to denser medium. The ray therefore gradually bend towards the normal and the sun appears to be raised . As a result the sun is visible to an observer nearly two minutes before actual sunrise at the horizon.