One of the most common examples of a mirage happens on highways during the summer. A car ahead may seem to be traveling through a shallow pool of water that forms a ripply reflection of the car. The reason for this false image is that a thin layer of heated air forms above the hot black pavement. This hot air meets the cooler air above, and light is bent—or refracted—where they meet. Light rays from the entering car are bent upward, and the inverted image is seen below the car. Light refracted from the blue sky looks like water on the ground. The “water” disappears as the observer approaches. A mirage similar to this one can lead people to think they are seeing a pool of water in the middle of a desert.

People have described various types of mirages. Many are seen around water because of the atmosphere there. For example, ships may seem to be sailing upside down above the horizon. One of the most famous of all mirages is the Fata Morgana. It is seen over the Strait of Messina between Italy and Sicily. Castles seem to rise from the sea and change shapes.