For Example, on a sunny, hot summer day, when you happen to be on a long, straight road, take a look at the surface of the road up ahead of the car. it often appears that there are pools of water on the road. what you are actually seeing is an optical illusion called a mirage.
The reason for this illusion is that under certain conditions, usually on hot sunny days, light beams bend when they hit the hot air close to the ground. instead of reaching the ground, they bounce up toward your eyes. what you see is a mirror image of something on the ground, a reflection that looks like a puddle.