Question

The setting sun appears higher in the sky than it really is:
A) True
B) False

Answer 1

Hint: The given problem seems to be similar to a situation of the apparent depth of a coin when placed in a beaker of water and viewed from a slant angle. The light rays from the coin get refracted at the surface of the water and reach the eye. Our eye is unable to trace the bent images and hence it forms a virtual image of the coin by extending the bent rays backwards to meet at a point higher than the actual depth of the beaker.

Complete step by step solution:
Refraction is defined as the change in direction of a wave when passing from one medium to another with different optical densities. Refraction of light is a commonly observed phenomenon, but sound waves and water waves also experience refraction, meaning that refraction is not only limited to electromagnetic rays.

The atmosphere around the earth has layers of air which do not have the same temperature. The hotter air is lighter and hence less dense than the cooler air. Due to the difference in the densities, the air layers have a different refractive index. When light rays pass through the atmospheric layers of different refractive index, then refraction takes place.

When light rays from the sun are incident at atmospheric layers, they suffer multiple refractions and the rays bend towards the surface of the earth. Our eyes, being unable to trace the bent rays, follow the incident rays backwards until we see an apparent image of the sun at a height more than its actual height.

Therefore, option (A) is the correct answer or the setting sun indeed appears higher in the sky than it is.

Note: Some other very important practical phenomenon observed because of atmospheric refraction are as follows:
1. The apparent flickering of an object seen through a turbulent stream of hot air rising above a fire, such as the flame of gas burners.
2. Twinkling of stars.
3. Advanced sunrise and delayed sunset.