i.
In the
atmosphere, there are different layers of air with different refractive indices
which keep on changing as the physical conditions of air are not stationary
(still).
ii.
When we observe
any object through this air, the light coming from them refract randomly due to
which the apparent position of the object fluctuates.
iii.
The large scale
effect of this phenomenon is the twinkling of stars, advanced sunrise and
delayed sunset.
iv.
Due to change in
the refractive index of atmosphere, the intensity of light that reaches our
eyes from the stars varies and hence the stars appear twinkling at night.
v.
Advanced sunrise
occurs as a ray of light from the sun enters the earth’s atmosphere; it follows
a curved path due to refraction before reaching to the observer.
vi.
It appears to
the observer as if the rays are coming from the position where the sun is seen
by the observer, hence, the sun is seen earlier before it reaches the horizon.
