Describe the formation of mirage through an appropriate figure.

Mirage is a type of optical illusion that is generally seen in deserts and in very cold regions.

When the light rays coming from tall objects pass through the air of gradually decreasing refractive index( as the air gradually becomes hot), the light rays bend gradually away from the normal and their angle of refraction increases gradually so that they enter observer’s eye after total internal reflection occurs. Hence, the image formed in a mirage is virtual and upside down.

Fig. Diagram of a mirage