Question

A bird flying high in the air appears to be higher than in reality. Explain why?

Answer 1

Hint: When attempting questions like the one given above keep in mind the concepts about temperature gradient and how it affects the perception of objects in different mediums. Remember the various refractive indexes of different materials and how it affects the pathway of light crossing through the mentioned materials.

Complete answer:
When we talk about refraction, we're talking about the bending of light (as well as sound, water, and other waves) when it passes through a transparent substance. We can have lenses, magnifying glasses, prisms, and rainbows because of this bending through refraction.
Real Depth is the true depth of an object beneath the surface, as measured by immersing it with a precise ruler. The depth of an object in a denser medium as perceived from a rarer medium known as apparent depth in a medium. It has a lower value than the actual depth.
The flying birds seem to be higher in the sky than they actually are due to temperature gradients.
The light beams of a bird refracted as they pass through the various layers of air. As a result, at each layer, the light rays bend towards the normal. The light from the bird appears to come from a place that is higher than its actual position due to continual refraction.
In simpler terms it means that when a bird is flying high in the air, it is in medium which is rarer to the ground whereas the air near the ground is denser. When we perceive the bird, light beams from the bird's body travel from a rarer to a denser medium, bending toward the normal.
This refraction of light causes the bird to appear flying higher in the air in contrast to what we see in reality.
Hence, we can conclude by saying that a bird flying high in air appears higher than in reality because of the phenomenon of temperature gradient surrounding refraction.

Note: When we talk about refraction, we need to remember the various laws surrounding refraction. First law states that the incident ray, refracted ray and the normal all lie in the same plane. And the second law we need to keep in mind is the Snell’s law of refraction which explains the relation between angles of incidence and refraction.