We are able to see the Sun even when it is a little below the horizon at sunrise and sunset. Which phenomenon is responsible for this?

1. The atmosphere's refractive index increases with decreasing height, so its layers refract light along a curved path. 2. The chapter states that when the Sun is below the horizon, its rays reach us along a curved path due to refraction through the earth's atmosphere. 3. Thus we see the Sun before it actually rises and after it sets. 4. Reflection, dispersion and absorption do not bend the rays around the horizon, so they are ruled out. _Source: Balbharati (Maharashtra Board) Class 10 Science & Technology, Ch 6 "Refraction of Light", p.86_