How does a mirage?

In the summer, in hot weather, when the sun shines brightly on the highway can be seen in the distance puddles reflecting the sky. In fact, there is no puddles: this visual deception, a mirage!

The water surface of the lake reflects the light rays and creates an image of riparian vegetation. Layer of air can also reflect light rays and create an inverted image of the landscape, located very far. This occurs when the hot weather: the heated air rises, and there is in contact with a cold layer of air.

Contact surface, like a mirror, reflects a waterless desert oasis of lush vegetation, which is very far away. In the same way on the highway sky reflected in the puddles, which is actually not.