Mirages like the ones that are shown on the road when you are driing are of course caused by heat but there i s uch more than just that. The most common mirage happens when something looks like it is being reflected looking like a puddle or pool of water on the ground or street (when your driving). This is known as light refraction-the bending of light beams. Light bends when it passes from one medium into another. An example would be when air goes into water or even from colder air to warmer air.

Mirages often occur when there is a sudden change in air density in the air-when the air at one level is hotter then the air at the next level. This usually happens when it is summer, like when the asphalt on the road has been baking in the sun all day and the sun heats the air right above it, creating the chang in air density by the ground. As the light passes between the different levels of air it bends and creates the mirages.

Usually the rays from the sun bounce off objects and go in all direction. Then you will see the oblect when it reflects in your eyes. On a day with lots of clouds you will only see the light that bounces right toward you. For more information go to the link provided. http://science.howstuffworks.com/mirage.htm/printable