Explain the occurrence of advanced sunrise and delayed sunset on the basis of atmospheric refraction.

Explanation

i. In the morning, the Sun should be seen by the observer when it reaches the horizon, but it is seen two minutes before that.
ii. As ray of light from· the Sun enters the earth's atmosphere, it follows a curved path due to refraction, before reaching the observer.
iii. This makes the apparent position of the Sun slightly higher than actual position for the observer. Hence, the Sun is seen earlier before the Sun reaches the horizon.
iv. Atmospheric refraction of sunlight also occurs at the sunset. In this case, the observer on the earth continues to see the setting Sun for two minutes after the Sun has dipped below the horizon, thus delaying the sunset.