CBSE Class 10 Answered

Sun can be seen about two minutes before actual sunrise because of refraction of sunlight through the atmosphere. When the sun is just below the horizon, sunlight enters the earth's atmosphere obliquely and gets refracted through the different layers of the atmosphere. As a result of this, sunlight gets bent and reaches the eyes of an observer. Following the path of the light rays entering the eyes, the observer sees the sun slightly above its actual position. As a result of this, sun can be seen about two minutes before the actual sunrise