Fata Morgana is an atmospheric phenomenon which produces bizarre, intriguing low-level visions along the horizon. These can be mysterious villages, or hills, ships or objects that become so distorted that it’s hard to tell what or where they are. This is a complex superior mirage. A mirage is an object that appears to be displaced from its original position. It can include objects beyond the horizon, looming. Ships or islands that appear double their normal height towering above the horizon. There will be layering in the distortion and inversion all, of which waver and alter adding to the mystical nature of the sights. It is caused by variations in the atmosphere, of air temperature which affects the density of the air, and this impacts the path of light, it causes it to bend.
It is not an illusion so you can photograph Fata Morgana. However, it does rely on your brain expecting light rays to travel in straight lines to your eye. In a Fata Morgana setup, the light rays are bent (refracted) by different density/temperature layers of air. As they curve, things over the horizon ‘become visible’ and as your brain interprets the straight-line view of where the image ‘must be’ they change apparent position.
It is a rare enough occurrence to feel special to see it. A few places around the world are more prone such as Alaska and other areas with ice cover. The name is linked to the Straits of Messina, a narrow body of water between Sicily and the toe of Italy. I’ve seen it a few times over the Firth of Forth, Scotland.
Fata is the Italian word for fairy. Fairy Morgana is Morgan le Fay, King Arthur’s half-sister and an enchantress. There are various tales around the Straits of Messina involving a powerful man gazing across the water and ‘seeing’ cities, churches, mountains even a volcano appearing. Wishing to own the lands, he would then encounter stunning Morgan le Fay rising out of the sea and she would entice him towards the new lands. And as of course, they didn’t exist the nobleman would then drown if he didn’t realise in time. The mirage would fade back to cypress trees, like witchcraft. Around the Sicilian coast, there is often a thin veil of mist which adds to the spooky conditions.
Progression of the mirage leading up to Top image
Initial haze but writing is clear
Deck house begins to stretch and distort, writing less clear
Superior mirage above with much layering and distortion of upper deck, not the hold as seen in top image where it is inverted. These variations come about due to changes in the temperature profile and duct.
There is a scientific explanation now, but the mirage is still most bizarre to behold. Sailors in centuries past would learn of the strange goings-on as they sailed far and wide. That ships on the horizon could be further away, as could land or lighthouses. That floating ships or even upside-down ones were not ghostly terrors. Nor devilish if they appeared and disappeared suddenly or even grew tall.
This image has been created during "DensityDesign Integrated Course Final Synthesis Studio" at Polytechnic University of Milan, organized by DensityDesign Research Lab in 2015. Image is released under CC-BY-SA licence. Attribution goes to "Ludovica Lorenzelli, DensityDesign Research Lab".other fields=, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons
There are two types of mirage. The common hot day, shimmering water one where we see ‘water’ on a hot road or surface, the oasis in a desert. This is an inferior mirage where the ground is much hotter than the air above it. The bright light is refracted upwards, away from the hotter area.
A superior image bends the light away from the cooler lower surface and floats above, inverted. All of this relates to the eye to brain messages expecting that the light is travelling in a straight line to you. It is not because it is being bent/refracted by the temperature contrasts of the air.
This image has been created during "DensityDesign Integrated Course Final Synthesis Studio" at Polytechnic University of Milan, organized by DensityDesign Research Lab in 2015. Image is released under CC-BY-SA licence. Attribution goes to "Ludovica Lorenzelli, DensityDesign Research Lab".other fields=, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons
Looming was a common maritime phrase for any objects appearing above the horizon. It is an exaggeration of a more everyday occurrence. Remembering that the earth is not flat, and the lower atmosphere can cause a little refraction (bending) of light rays due to the usual change in air pressure and density away from the surface. The object doesn’t alter in appearance, just appears up a bit.
“This phenomenon of atmospheric refraction makes extra-terrestrial objects such as the Sun and Moon appear above the horizon for a few minutes after they've set and is well-known to astronomers as astronomical refraction. What’s being observed is looming -- an exaggeration of normal refraction, produced by a steeper than usual decrease in density with height.” USRA
Isle of May growing tall and deformed in the Firth of Forth
Abnormal refraction causes objects ‘to lift” and almost look large, nearer than usual. The effect is usually due to a thermal inversion. Usually, the temperature in the lower atmosphere decreases with increasing height. When warmer air is above colder air it is known as a thermal inversion or inversion layer. This is the first ingredient for Fata Morgana as a thermal inversion is required to produce a superior mirage.
“The elevation of coasts, ships and mountains above their usual level, when seen in the distant horizon, has long been known and described in the name of Looming”
Towering – if the temperatures profile is not constant with height, there can be vertical stretching of an image in the distance. Again, it is a result of refraction, no inversion and this is called towering. The opposite is stooping where the image is squashed down and compressed. Both can add into the complex mirage of Fata Morgana
A duct is a passageway. When looking at the rain radar we are taught about AnaProp - Anomalous Propagation where, under certain still atmospheric conditions, the radar beam can get trapped in a lower of the lower atmosphere rather than fading away into the sky in a straight beam. Radio operators revel in this as they can reach callers huge distances away temporarily.
The second ingredient for Fata Morgana is an atmospheric duct. This is needed to manoeuvre the light rays of the complex mirage to the viewer. Not allow them to head off into the sky. The Fata Morgana is a low-level phenomenon, occurring along the horizon. You don’t need to be high up yourself to see it.
The Isle of May on a more usual day but with colour layering visible in the sea
A False Horizon - There have been pictures online of boats seemingly floating in mid-air, often on a still day. This isn’t Fata Morgana. Often the sea is just about visible but there is an illusion and colour change that makes it look like a layer of the sea is the same colour as the sky. Haze can add into the picture. You can pull the colour contrasts to check and looks for other clues in the wider image. The Flying Dutchman phantom ship could have been one of these or looming over the horizon.
It is a complex mirage, a combination of inversion, towering, looming there will be distortion effects but all within a shallow layer along the horizon. In the Firth of Forth, Bell Rock lighthouse is barely visible from the north coast of East Lothian but can loom over the horizon and appears near to the towering Isle of May in Fata Morgana episodes.
The Bell Rock light house seen in the distance from SW of Isle of May and in Fata Morgana from just SE, much taller and inverted
When cold air is near the surface and warm air lies just above it the rays of light are bent (refracted) towards the cooler air or sea. The atmospheric duct acts like a refractive lens and produces inverted and erect images. These merge and distort which adds to the mystery before you. You have to be at the right level to see the effect, not too high up and the curvature within the duct has to be greater than the usual curvature of the earth’s surface. The effect can be fairly rapid and changeable. IN the Straits of Messina, the hills and villages appear and disappear. But in the Firth of Forth some kind of mirage can be visible for hours. It is easier to spot if you are familiar with how the landscape should look. Ships are more tricky except when they distort or invert.
If you do see something weird on the horizon, it could be down to bending light rays and you’re not going crazy if you see an upside-down ship or very tall 'new' lighthouse.
With many thanks to Kenny Maule for additional photos