what causes the mirage to appear?

Question

Our brains can be tricked by the things we see. For example, on a sunny day a mirage of a pool of water may appear on the road.

Answer 1

It is known that light waves are bent away from the normal due to refraction while travelling from a denser to a lighter medium.
Near the hot ground(or road) on a sunny day,air very near the ground becomes extremely hot and light,while air considerably above the ground remains dense.Light rays from a distant object coming towards the ground are continuosly refracted away from the normal and undergo total internal reflection and the image of the object appears to come to the observer as if after reflection from a water surface.This optical illusion is known as the mirage.

Answer 2

What Creates A Mirage

Answer 3

Almost all mirages are "refraction" mirages. Refraction simply means the bending of light. And a mirage is caused by light being "bent" by the rising currents of heated air coming off of any heated surface, the most usual example being the horizon in the desert. Since the heated air is less dense (that's why it's rising) than the air above, it bends (refracts) the light coming to your eye along the ground level creating false images along the horizon (the appearance of "water" is merely a reflection of the sky above projected onto the plane of the ground by refraction).

Answer 4

Just a comment on Utarch's answer. The fact that the air near the ground is hotter and less dense than air higher up is what causes light to refract/bend. It has nothing to do with the fact that air is rising.

Answer 5

I agree with the above although also dehydration can cause people to imagine seeing things which is another reason people see mirages although i guess you'll go with the other guys response :P

Answer 6

change in density of the layers of air very close to the ground on a hot day.

The hot ground heats the layers of air and they have changed refractive indices, causing the light to "bend"