Mirages

Until I saw my 1st photograph of a mirage (I was in my teens), I didn't think they could be caught on film. But of course they can, just like the refraction of a knife in a glass of water. A mirage is a trick of the light, not a trick of the brain. The optical phenomenon occurs when light rays are bent to produce a displaced image of distant objects or the sky. How we interpret these is a function of our minds, however, for instance a mirage of the sky appearing on the ground is often interpreted as pools of water (1st image). Mirages are described as inferior if the image is refracted below itself, superior if it is refracted above itself. A 3rd type of mirage called a fata morgana is a complicated series of rapidly moving, vertically stacked images. The science quickly becomes too hard for me to understand, but basically the light rays are bent when they cross sharp boundaries between warmer and cooler (less dense) air. These distinct boundaries are formed when a certain temperature gradient as reached, such as when there is strong heating at ground level caused by the sun shining on sand or asphalt. The angles at which the light rays are refracted determine whether the mirage is upside down. Because hot air rises, inferior images are not stable, which is why they are distorted and may vibrate (2nd image). Shown here are an inferior mirage in the desert (3rd image), a superior image in the Antarctic (4th image), and a superior image off the east coast of China in which skyscrapers, streets, cars, and crowds were clearly visible (5th image).