A Fata Morgana (Italian: [ˈfaːta morˈɡaːna]) is a complex form of superior mirage visible in a narrow band right above the horizon. The Italian term Fata Morgana translates the name of the Arthurian sorceress Morgan le Fay ("Morgan the Fairy"), due to a belief that these mirages, often seen in the Strait of Messina, were fairy castles in the air or false land conjured up by her witchcraft to lure sailors to their deaths.
Fata Morgana mirages significantly distort the object or objects on which they are based, often such that the object is completely unrecognizable. A Fata Morgana may be seen on land or at sea, in polar regions, or in deserts. It may involve almost any kind of distant object, including boats, islands, and the coastline.
Often, a Fata Morgana changes rapidly. The mirage comprises several inverted (upside down) and erect (right-side up) images that are stacked on top of one another. Fata Morgana mirages also show alternating compressed and stretched zones.
- info at (for example) wikipedia: https://en.wikipedia.org/wiki/Fata_Morgana_(mirage)