What is a Mirage?
Puddles don’t just evaporate instantly into thin air. Buildings don’t shimmy like belly dancers. But sometimes, mirages make faraway objects look like they’re rippling. “A mirage is an inverted image produced by atmospheric refraction,” says Andrew Young, an astronomer at San Diego State University. Atmospheric refraction occurs when varying air densities cause the sun’s rays to bend, moving in directions other than the normal straight lines. “When refraction is strong enough to produce inverted images, it usually produces multiple images and distortions as well,” Young explained, “and that refraction displaces images only in the vertical direction, not sideways. Everything we see appears slightly displaced from its geometric direction by refraction caused by density gradients in the air.” Mirages are often seen on the streets on sunny days. These are produced by warmer air developing at the surface, where dark asphalt is heated by solar energy. They’re known as “inferior mirages” beca
There are two types of mirages: inferior and superior. Mirages are caused by light refraction, which is the bending of light waves. Refraction occurs when light goes through one type of material into another. For example it may pass through air and go into water. Light can also be refracted when it passes through an area of warm air into an area of cooler air because cold air has a higher density than warm air. In an inferior mirage, which is the most common type, an object seems to be present as if it were both the actual object and its reflection in a pool of water. When the ground is very hot, heat radiates up out of the ground and warms the air directly above it. When light passes through the cooler air above into the warmer air below, it bends and creates a mirage. The mirage looks like an object that is reflected in water because part of the light would usually go to the ground, but it is bent and goes up to your eyes instead, creating a double image. Inferior mirages are commonl
