Advanced sunrise and delayed sun- set found in the sky are due to the phenomenon of

The phenomena of advanced sunrise and delayed sunset are primarily caused by the atmospheric refraction of sunlight [2]. As sunlight enters the Earth's atmosphere, it passes through layers of varying air density, which causes the light to bend or refract [2]. This bending allows the Sun to be visible to an observer even when it is physically below the horizon [1]. Specifically, the Sun appears about 2 minutes before the actual sunrise and remains visible for about 2 minutes after the actual sunset [2]. This occurs because the atmosphere acts as a refractive medium, making the Sun's apparent position higher than its actual position. Other phenomena like scattering contribute to the sky's color, but the shift in timing and position is strictly due to refraction [1].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 10: The Human Eye and the Colourful World > Advance sunrise and delayed sunset > p. 168
2. [2] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 19: The Motions of The Earth and Their Effects > Days Are Always Longer Than Nights at The Equator > p. 255