Fata morgana

From Glossary of Meteorology

fata morgana

A mirage, but the specific physical circumstances under which fata morgana should be applied to a particular sighting are ill-defined.

The best that can be said is that the mirage interacts with features in the landscape to present a scene of sufficient ambiguity that viewers often arrive at quite fanciful interpretations. Cases reported include those of the apparent sighting of cities, mountains, forests, or islands (sometimes metamorphosing one into the other) in places where it was known that no such things existed. Indeed, the mirage's eponym is the fairy Morgan, the legendary half-sister of King Arthur, whose magical powers enabled her to create castles in the air ("fata" is Italian for "fairy"). It is not that any particular occurrence is the least bit mysterious or that either the meteorological or optical behavior is difficult to understand. Indeed, most cases of the fata morgana are undoubtedly multiple- image superior mirages, sometimes with marked magnification, sometimes complicated by periodic inhomogeneities, sometimes augmented by an inferior mirage.
Compare fata bromosa.