The sun is visible to us about 2 minutes before actual sunrise and about the actual sunset.give reasons.
The Sun is visible to us two minutes before the sunrise (advance sunrise) and two minutes after the Sunset (delayed sunset), because of the bending of the light due to atmospheric refraction. The light from the Sun got refracted by the atmospheric layers and reaches the observer. This causes the observer to think that the light is coming straight from the Sun.
During morning hours, the sky will be filled with water molecules and other particles. Due to gradually increasing refractive index, the sun when below the horizon, its light bends. Due to this, the apparent position of the sun appears little raised.
Similarly, during evening hours, the sky will be filled with water molecules. As the apparent position of the sun appears raised, the sun gets set before 2 minutes and its apparent position sets after 2 minutes.
Here, both the pictures show the position of the observer.
Hope this helps u............