Fascinating Meteorology Terms: Fata Morgana

(Photo of a Fata Morgana mirage over water by Pekka Parviainen)

(Diagram by Tom Phillips)

Fata Morgana is a term given to a type of mirage that occurs over water. This type of mirage is famous for its ability to make ships and islands appear to be floating in thin air. The origin of the term stems back to Italy over the Strait of Messina. It was claimed that castles or buildings would appear out of thin air over the strait and then vanish within seconds. Fata Morgana is Italian for Fairy Morgan whom was a mythical being in the fairy tale of King Arthur. In her tale, she lived in a castle underwater and her mystical powers gave her the ability to build castles out of thin air and destroy them just as quickly. This is exactly how the Fata Morgana mirage is observed and how it came to get its name.
    
Mirages are defined as an object that appears to be displaced from its original position. Experiencing a mirage feels as if your eyes are playing tricks on you, when in fact, it is the atmosphere that is tricking you. Unlike hallucinations, mirages can be depicted in pictures. This provides proof for people experiencing the phenomenon that the objects being viewed do indeed exist. Many mirages are created by light passing through layers of air that have different densities. Air density is determined by air temperature. Colder air is associated with a higher density as warmer air is associated with lower density. When light hits an area of higher or lower density, it bends at a different angle. This is called refraction of light.
    
Fata Morgana is created from refraction of light through warm air settling on top of a cold surface such as water. For example, in the diagram below, light reflected off the object passes through cold air settled above that cold surface of water. As that light begins to pass through a warmer pocket of air above that cold surface, the light will start to bend as the air it passes through gets warmer. Eventually, that light would bend in such a way that it reaches the eyes of the observer at a different angle making the object appear to be floating. Now it is pretty clear why so many people claimed to see floating ships or islands over the strait of Messina in Italy. A lot of the light that reflected off ships and the land across the way was refracted into their eyes at a different angle.
  





Fata Morgana is called the superior mirage. A superior mirage occurs where an object appears to be above its original position. An inferior mirage, the opposite of superior mirages, occurs when the object appears to be below or upside down its original position. This happens when light is bent upward from its original path. Along with Fata Morgana being such a superior mirage, it is also a superior meteorology term with a very fascinating origin from Arthurian legend.   

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© 2019 Meteorologist Alex Maynard

  

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