Sat March 12, 2011 By: Chandranath Jha

why there is advanced sunrise and delayed sunsets.........

Expert Reply
Sat March 12, 2011
Dear student

Advance sunrise and delayed sunset

The Sun is visible to us about 2 minutes before the

actual sunrise, and about 2 minutes after the actual

sunset because of atmospheric refraction. By actual

sunrise, we mean the actual crossing of the horizon by

the Sun. Fig. 11.10 shows the actual and apparent

positions of the Sun with respect to the horizon. The

time difference between actual sunset and the apparent

sunset is about 2 minutes. The apparent flattening of

the Sun’s disc at sunrise and sunset is also due to the

same phenomenon.


Hope this clarifies your doubt.




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