In polar regions the Fata Morgana phenomenon is observed on relatively cold days. It may, however, be observed in almost any area. While a thermal inversion often takes place without there being an atmospheric duct, an atmospheric duct cannot exist without there first being a thermal inversion.Ī Fata Morgana is most commonly seen in polar regions, especially over large sheets of ice that have a uniform low temperature. A Fata Morgana requires a duct to be present thermal inversion alone is not enough to produce this kind of mirage.
Superior mirage series#
In calm weather, a layer of significantly warmer air may rest over colder dense air, forming an atmospheric duct that acts like a refracting lens, producing a series of both inverted and erect images. An observer needs to be within or below an atmospheric duct in order to be able to see a Fata Morgana. It will guide the rays along the surface of the earth rather than shooting out into space. If the thermal inversion is strong enough (greater than 10 degrees C in 100 meters), the curvature of the light rays within the inversion layer is stronger than the curvature of the Earth (called “super-refracting”), thus trapping them. Like other superior images, a Fata Morgana occurs because rays of light are bent when they pass through air layers of different temperatures in a steep thermal inversion where an atmospheric duct has formed. Fata Morgana mirages also show alternating compressed and stretched zones. The mirage comprises several inverted (upside down) and erect (right side up) images that are stacked on top of one another.
It may involve almost any kind of distant object, including boats, islands, and the coastline. A Fata Morgana may be seen on land or at sea, in polar regions, or in deserts. Although the term Fata Morgana sometimes is applied to other more common kinds of mirages, true Fata Morgana is different from both an ordinary superior mirage and an inferior mirage, in which the image appears below the actual object.įata Morgana mirages significantly distort the object or objects on which they are based, often such that the object is completely unrecognizable. It is an Italian term named after the Arthurian sorceress Morgan le Fay, from a belief that these mirages, often seen in the Strait of Messina, were fairy castles in the air or false land created by her witchcraft to lure sailors to their deaths. This example shows a ship that appears to be floating above the horizon Fata MorganaĪ Fata Morgana is a complex form of superior mirage that is seen in a narrow band right above the horizon. Superior mirages can also distort images so that the object appears stretched and elevated, called towering.įataMorgana photographed off the Queensland coast, 26 August 2012 (Source: Timpaanen, Wikicommons). This is known as a looming type of superior mirage. Superior mirages can produce a few different types of images: distant objects can appear to float high above their actual position, for example a boat can look like it is floating in the sky, or an object below the horizon can become visible. Often the image appears as a distorted mixture of up and down parts. A superior mirage can be right-side up or upside down, depending on the distance of the true object and the temperature gradient. Superior mirages can make things appear bigger, closer, or suspended in air. Superior mirages can make objects below the horizon visible at least in some form or distort the image of an object at the horizon. Most superior mirages tend to be stable, as cold air has no tendency to move up and warm air has no tendency to move down.
Passing through the temperature inversion, the light rays are bent down, and so the image appears above the true object, hence the name superior. Superior MirageĪ superior mirage occurs when there is a temperature inversion the air below the line of sight is colder than the air above it. In particular, a Fata Morgana is a superior mirage. Refraction refers to the bending of, in this case, light waves as they move through mediums of different density, typically layers of air with different temperatures. A mirage is an image caused by atmospheric refraction.
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