Superior Mirage
A superior mirage occurs when an image of an object appears above the actual object, due to the refraction or bending of light waves from the object down toward the eyes of the observer. Downward refraction occurs because air closer to the ground is colder, and therefore more dense, than air higher up.
Superior mirages can take the form of looming, towering, and inversion, depending on the particular density structure of the air column.
In looming, distant objects appear to float above the horizon, and objects that are below the horizon may come in to view. In towering, rays from the upper portion of an object are bent more than those from the lower portion. This results in the object appearing to be stretched as well as elevated.
The towering mirage ( Sechrist et al. 1989)
In a superior mirage with an inverted image, the gradient in atmospheric density is so sharp that rays from the lower portion of an object are bent considerably more than rays from the upper portion of an object, causing a mirage of the object to appear inverted above the object. The object appears as it normally would at the same time, because some light continues to travel to the eye directly from the object.
The superior mirage (Sechrist et al. 1989)
Fata Morgana
The fata morgana is a complex mirage in which distant objects are distorted as well as elongated vertically. For example, a relatively flat shoreline may appear to have tall cliffs, columns, and pedestals. The phenomenon occurs under much the same meteorological conditions as the superior mirage with inversion, and contains features of both towering and inversion.
Aurora Borealis | Halos and Sun Dogs | Coronas | Water Sky | Superior Mirages | Optical Haze