Question

Which of the following are examples of atmospheric refraction?

• A. Twinkling effect of stars
• B. Flattening of Suns disc
• C. Wavering of objects in hot air
• D. All of these

Answer 1

The correct option is D All of these

Hot air is lighter than cool air and hence is less dense. It has refractive index slightly less than that of cool air. Since the physical conditions of the refracting medium (air) are not stationary, the apparent position of the object seems to fluctuate when seen through hot air. The twinkling of a star is due to atmospheric refraction of starlight as the starlight undergoes continuous refraction before it reaches the earth. As the path of rays of light coming from the star goes on varying slightly, the apparent position of the star fluctuates and the amount of starlight entering the eye flickers i.e. the star sometimes appears brighter, and at some other time, fainter, which is the twinkling effect. The apparent flattening of the Suns disc at sunrise and sunset is also due to the same phenomenon.