Question

“Looming” in the polar region.
A. is an optical illusion.
B. arise due to variation of the refractive index of the atmosphere.
C. is an example of total internal reflection
D. All of the above,

Answer 1

Hint: There are different types of optical illusion, looming is one of them. Looming in optics can be defined as a deceptive appearance of a distant object caused due to bending of light rays in layers of air with varying density. Due to the bending of light, objects either appear to be floating in the sky above its actual position or the object below the horizon can also become visible.

Complete answer:
Looming is an optical illusion which increases the apparent elevation of the object and also sometimes allows the observer to see the objects that are located below the horizon under normal conditions. In the polar region, the cold air lies close to the ground with warmer air above it. Since, cold is much denser as compared to warm air. It bends light towards the eyes of the observer standing on the ground, changing the appearance of distant objects. Due to the bending of light, the object appears to float high above its actual position. This is known as looming.
Thus, looming in the polar region is an optical illusion arising due to variation of refractive index of the atmosphere and is an example of total internal reflection.

So, the correct answer is option D i.e. All of the above.

Note:
Students must not get confused between mirage and looming. There are few similarities between them while a lot of differences. The similarity between them is that more are results of total internal reflection of light. The difference between them is that the mirage takes place in hot regions whereas the looming takes place in cold regions. Another difference between them is that in case of mirage, the light from distant objects appear to be reflected from ground whereas in case of looming, the distant objects appear to be flying.