The Misleading Appearance: Mirage

“Mirage: An optical effect that is sometimes seen at sea, in the desert, or over a hot pavement, that may have the appearance of a pool of water or a mirror in which distant object are seen inverted, and that is caused by the bending or reflection of rays of light by a layer of heated air of varying density.”(Merriarn-Webster’s Medical Dictionary)
Imagine yourself walking alone in the desert, you haven’t drink any water for a long time, you were tired, thirsty and exhausted. Suddenly, there was something catching your eyes, a pond far away in the front. You faster your pace to get there as soon as you can, however, the pond disappeared. Where did it go? The phenomenon in this situation is called Mirage, and it doesn’t happen very often in the nature. Usually this phenomenon is caused by refraction and the vary density of the air. As we learned in the lecture, refraction is the light bending when it travels through different index of material. The good example for the refraction is the straw in the glass of water; the straw looks broken in the water. The different index of air and water makes the light bending and it reflects back to our eyes as virtual image. Same theory applies to the Mirage, when the light travels through the different layer of air, the refraction occur because the density of each layer is different. The light is bending and creates the virtual image, that’s the illusion we see as the Mirage. That explains why the pond disappear all the sudden at nowhere in the dessert. There are two different types of mirage such as Superior Mirage and Inferior Mirage. Superior Mirage is the image on the top of the actual object; and Inferior Mirage is the image below the actual object. The cause of Superior Mirage and Inferior Mirage is the opposite patterns of temperature change in height. The density of the air changes when the pressure, temperature, and humidity in the air changes. When the height is different, those factors above can be