Look at the photo below

Advanced Sunrise - Example.jpg

Here, we see sun above the horizon, but the sun is actually not above the horizon.

 

Infact:

We see sunrise 2 minutes before actual sunrise

We see sunset 2 minutes after sunset

This is because of atmospheric refraction

 

Explanation for Advanced Sunrise

Before Sunrise, sun is below the horizon

Sun's rays are coming from more dense air towards less dense air

This causes sun rays to refract and appear to come above the horizon

Our eyes see sun rays as a straight line, it appears to us that sun has risen but it has actually not yet risen

Explanation for Delayed Sunset

After Sunset, Sun is below the horizon

Sun's rays are coming from more dense air towards less dense air

This causes sun rays to refract and appear to come above the horizon

Our eyes see sun rays as a straight line, it appears to us that sun has not yet set

Reason of Advanced Sunrise and Delayed Sunset - Teachoo.png

What about Flattening of Sun's Disc?

During sunrise and sun's set, shape of sun appears to be little flatter

This is also because of refraction of light (bending of light coming from sun to earth due to earth's atmosphere)

  1. Class 10
  2. Chapter 11 Class 10 - Human Eye and Colourful World

About the Author

Davneet Singh's photo - Teacher, Computer Engineer, Marketer
Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.