The appearance of the inferior mirage indicates that the surface air is much warmer than the air above it due to the strong heating of the surface by the sun. The superior mirage occurs under reverse atmospheric conditions from the inferior mirage. For it, the air close to the surface must be much colder than the air above it. This condition is common over snow, ice and cold water surfaces. When very cold air lies below warm air, light rays are bent downward toward the surface, thus tricking our eyes into thinking an object is located higher or is taller than it actually is.
Scale is greatly exaggerated.
The superior mirage can also make objects appear to be taller than they actually are, a condition called towering . The image often appears inverted as well. The weather conditions that form superior mirages are quite common at night when radiational cooling of the air near the surface, under clear skies and light winds, is strong. Mirages at this time are seldom noticed, however, since it is usually dark. But artificial lighting, particularly from buildings and vehicle headlights, can be lofted from their expected position.