Question

Write a short note on “Refraction observed in the atmosphere”.

Answer 1

Hint : Refraction is the bending of a light ray as it travels through different mediums. We know that the earth’s atmosphere is made up of several layers which will act as different mediums for the ray of light.

Complete step by step answer
We know that when a light gets refracted when travelling from one medium into the other, it gets deviated from its original path. This happens due to the difference in the velocity of light in the two mediums. The difference in the velocities of light in the two mediums is because of the difference in the optical densities of the mediums.
When a ray light from a distant object in space enters the earth’s atmosphere, it travels through different layers of the atmosphere. We know that the density of air decreases with increasing altitude. So the density of air is low at the high altitudes and is higher below. This difference in the density of air results in the difference in the velocity of light in different layers of the atmosphere. This results in the difference in the refractive indices of the different layers. Also, the refractive index of each individual layer keeps on changing. So the original path of the entered ray is deviated and due to this the observed position of the distant object is different from the actual position.

Note
The atmospheric refraction is responsible for many interesting phenomena observed in nature. For example, the stars appear to be twinkling to us. This is because of the bending of light through different layers of the earth’s atmosphere, whose refractive index is not fixed. So the number of rays entering our eyes keeps on changing due to which the stars appear to be twinkling.