mirage

An optical illusion due to the deviation undergone by the sun's rays as they cross the lower stretch of the atmosphere, located near the Earth's surface, when there is a strong vertical temperature gradient there, which substantially modifies the refractive indices of the air. The phenomenon, also known as espejeo - from the Latin speculum (mirror) -, alters our visual perception of objects far from us, on the horizon. Stable or shimmering images of them are formed, which, depending on the type of mirage, we see distorted, repeated, inverted, or displaced from their original position.