Fata Morgana

There’s an interesting atmospheric phenomenon called Fata Morgana that will make an appearance along the horizon over the Ross Sea and Ice Shelf every now and then, and it is quite an awesome sight when you can see it right from McMurdo Station! The first time I saw it I didn’t know what was going on, so I took the opportunity to educate myself about it, and I would like to share that with all of you in this post, along with some pictures, of course!

fa·ta   mor·ga·na (fä’tә môr-gä’nә): n. (Physics/General Physics) a mirage, attributed to the sorcery of Morgan le Fay [Italian, mirage, Morgan le Fay (from the belief that the mirage was caused by her witchcraft)fatafairy (from Vulgar Latin fātagoddess of fate) + Morgana, Morgan (probably from Old Irish Morrigain).]

A Fata Morgana is a type of complex mirage in which objects that are far away (particularly along the horizon in your field of view) are either distorted, inverted, or stretched in the vertical direction (or sometimes all of the above at the same time) so as to appear larger than they actually are. This type of mirage is commonly seen in the Polar Regions on cold days, as well as out in the open sea. Here’s a mild example of it:

View of Mt. Discovery across the sound from McMurdo station. The thick band that you see at the base of the mountain, which looks like a tall cliff, is not actually there. This is a Fata Morgana mirage (see the next image).© A. Padilla
View of Mt. Discovery across the sound from McMurdo station. The thick band that you see at the base of the mountain, which looks like a tall cliff, is not actually there. This is a Fata Morgana mirage (see the next image).
© A. Padilla
View of Mt. Discovery across the sound from McMurdo station. Note that the thick band at the base of the mountain (from the picture above) is absent.© A. Padilla
View of Mt. Discovery across the sound from McMurdo station. Note that the thick band at the base of the mountain (from the picture above) is absent.
© A. Padilla

If you’re as curious as I am, at this point you’re probably asking yourself how this happens. I’ll do my best to simplify the explanation (it took me quite some time and a lot of reading the same thing over and over again before I got a good grasp on it).

First off, there are a couple atmospheric conditions that are needed before you can see a Fata Morgana. One of those is that, of course, it has to be a cold day. This is important for another one of the required conditions: the presence of a “thermal inversion.” The way our atmosphere works is that as you go higher and higher the air gets colder and thinner (it expands and loses energy). A thermal inversion simply means that this pattern is reversed (or inverted): you get hot air sitting on top of cold air. On a really cold day, you can get a layer of hot air that flows over a layer of cold air, and the hot air can stay on top because it is less dense than cold air. If the temperature gradient is sharp enough (it goes from cold air below to hot air above over a relatively short distance) it will create something called an “atmospheric duct,” or a horizontal layer, in the lower atmosphere that can guide (or “duct”) light rays when they pass through it, following the curvature of the Earth. Another way of thinking about it is that, because the optical density and therefore the optical properties of hot air is also lower than those of cold air, you essentially end up with an optical lens (much like a camera lens) that can bend and re-direct the light as it goes through it. The presence of this atmospheric duct is very important because this is what creates the Fata Morgana: light is bent in the duct and arrives at your eye from a different direction than that from which it originated, making it seem like there is an object there. Here are a couple of illustrations that might help you understand that:

In this figure, the dashed lines indicate the direction in which the man on the left is looking (upward toward the sky), and the lines with the arrows indicate the direction in which the light was traveling. The curvature of the light path reflects the effect of the atmospheric duct (hot air above, cold air below), thus creating the mirage seen on the upper right side as the light arrives at the observer’s eyes from the same direction in which he is looking after being bent.(Image source: Astronomy.org)
In this figure, the dashed lines indicate the direction in which the man on the left is looking (upward toward the sky), and the lines with the arrows indicate the direction in which the light was traveling. The curvature of the light path reflects the effect of the atmospheric duct (hot air above, cold air below), thus creating the mirage seen on the upper right side as the light arrives at the observer’s eyes from the same direction in which he is looking after being bent.
(Image source: Astronomy.org)
A different illustration of the same process described in the figure above, with one slight difference: in this figure, the light travelling from the bottom of the object (the pine tree) to the observer’s eye is travelling at a slightly different angle than the light travelling from the top of the object, and thus arriving at the observer’s eyes from slightly different directions resulting in an optically inverted mirage (the upside down pine tree). Again, the dashed lines represent the direction in which the observer is looking, and the solid lines represent the bent light paths. The graph on the left side of the figure shows temperature (on the x-axis) increasing with altitude (on the y-axis).(Image source: National Snow & Ice Data Center)
A different illustration of the same process described in the figure above, with one slight difference: in this figure, the light travelling from the bottom of the object (the pine tree) to the observer’s eye is travelling at a slightly different angle than the light travelling from the top of the object, and thus arriving at the observer’s eyes from slightly different directions resulting in an optically inverted mirage (the upside down pine tree). Again, the dashed lines represent the direction in which the observer is looking, and the solid lines represent the bent light paths. The graph on the left side of the figure shows temperature (on the x-axis) increasing with altitude (on the y-axis).
(Image source: National Snow & Ice Data Center)
Another look at the optical inversion, though slightly exaggerated as the light rays (solid lines) do not actually bounce off the boundary (or duct) between the hot and cold layers of air, but rather bend as they approach and cross it. Perhaps it is easier to understand the inversion by looking at it this way. Again, the dotted line indicates the direction in which the observer is looking, and thus the location where the mirage is seen.(Image source: Leifi Physik)
Another look at the optical inversion, though slightly exaggerated as the light rays (solid lines) do not actually bounce off the boundary (or duct) between the hot and cold layers of air, but rather bend as they approach and cross it. Perhaps it is easier to understand the inversion by looking at it this way. Again, the dotted line indicates the direction in which the observer is looking, and thus the location where the mirage is seen.
(Image source: Leifi Physik)

These figures basically depict a single point of the mirage (only one reflection, in a perfect situation), but if you can imagine that if you look in-between the mirage and the actual object you will see many other mirages of the same object, then you’re essentially imagining what happens during the Fata Morgana: you end up with a lot of mirages stacked on top of each other filling up that space, stretched from the actual object upwards into the atmosphere (the larger the atmospheric duct, the larger the effect will be) and with alternating inverted and right-side-up images, giving you the final view of a Fata Morgana.

Below are some pictures of the Fata Morgana that we have seen across the McMurdo Sound. Pretty amazing!

Emperor Penguins marching across the Ross Sea Ice, with Black Island and a thin Fata Morgana in the background.© A. Padilla
Emperor Penguins marching across the Ross Sea Ice, with Black Island and a thin Fata Morgana at its base in the background.
© A. Padilla
Emperor Penguins huddle on the Ross Sea Ice, discussing which way to go as they are clearly lost. You can see a thin Fata Morgana at the base of Black Island in the background, and on the very right edge within the Fata Morgana you can barely catch a glimpse of the Pegasus Airfield, enlarged by the mirage!© A. Padilla
Emperor Penguins huddle on the Ross Sea Ice, discussing which way to go as they are clearly lost. You can see a thin Fata Morgana at the base of Black Island in the background, and on the very right edge within the Fata Morgana you can barely catch a glimpse of the Pegasus Airfield, enlarged vertically by the mirage!
© A. Padilla

Fata Morgana at the base of Hobbs Peak, in the Royal Society Mountains, just across the sound from McMurdo Station.© A. Padilla
Fata Morgana at the base of Hobbs Peak, in the Royal Society Mountains, just across the sound from McMurdo Station.
© A. Padilla
Hobbs Peak, in the Royal Society Mountains, without a visible Fata Morgana.© A. Padilla
Hobbs Peak, in the Royal Society Mountains, without a visible Fata Morgana.
© A. Padilla

Fata Morgana seen at the base of Cape Hodgson & the Pegasus Airfield, out in the middle of the Ross Ice Shelf. The Pegasus buildings appear much taller and bigger than they actually are.© A. Padilla
An incredible Fata Morgana seen along the coast of Cape Hodgson, Black Island, and at the Pegasus Airfield, out in the middle of the Ross Ice Shelf. The Pegasus buildings appear much taller and bigger than they actually are.
© A. Padilla
Cape Hodgson, on Black Island, and the Pegasus Runway on the Ross Ice Shelf, seen without the Fata Morgana.© A. Padilla
Cape Hodgson, on Black Island, and the Pegasus Runway on the Ross Ice Shelf, seen without the Fata Morgana.
© A. Padilla
The southwest edge of Black Island with a well-developed Fata Morgana.© A. Padilla
The southwest edge of Black Island with a well-developed Fata Morgana.
© A. Padilla

A well-developed Fata Morgana at the base of Black Island (right) and along Minna Bluff (the slightly faded terrain at the left third of the picture, which is actually about 30 miles beyond Black Island.© A. Padilla
A well-developed Fata Morgana at the base of Black Island (right) and along Minna Bluff (the slightly faded terrain at the left third of the picture, which is actually about 30 miles beyond Black Island.
© A. Padilla
Minna Bluff, at the edge of the Antarctic Continent, with an incredible Fata Morgana.© A. Padilla
Minna Bluff, at the edge of the Antarctic Continent, with an incredible Fata Morgana.
© A. Padilla
Minna Bluff without the Fata Morgana effect.© A. Padilla
Minna Bluff without the Fata Morgana effect.
© A. Padilla

I have been keeping an eye out across the McMurdo Sound, trying to capture other cool Fata Morgana, but it’s been quite warm these past few weeks that we haven’t really seen much of it. As we head into the end of summer we will start getting more cold days and hopefully we’ll see more Fata Morgana. I will do my best to add some more pictures to this post through the rest of our time here!

In the meantime, enjoy these other beautiful examples of Fata Morgana from around the world (click on images for source link):

Superior Mirage, or Fata Morgana, of boats at sea.Author: Frank R. Stockton
Superior Mirage, or Fata Morgana, of boats at sea.
Author: Frank R. Stockton
"Mirage in The Aerial World." An illustration of Fata Morgana, or a Superior Mirage, off the coast from a desert.Author: Dr. G. Hartwig
“Mirage in The Aerial World.” An illustration of Fata Morgana, or a Superior Mirage, off the coast from a desert.
Author: Dr. G. Hartwig
Example of a Fata Morgana off the coast, location unkown.(Source: Wikipedia)
Example of a Fata Morgana off the coast, location unkown.
(Source: Wikipedia)
Fata Morgana observed at Ocean Beach, San Francisco, CA.© Mila Zinkova (via Earth Science Picture of the Day)
Fata Morgana observed at Ocean Beach, San Francisco, CA.
© Mila Zinkova (via Earth Science Picture of the Day)
Fata Morgana of a ship in Nieuw-Haamstede, Zeeland, The Netherlands.© Meneer Zjeroen
Fata Morgana of a ship in Nieuw-Haamstede, Zeeland, The Netherlands.
© Meneer Zjeroen
Fata Morgana in the mountains, location unknown.(Source: RecapWhenNotInUse)
Fata Morgana in the mountains, location unknown.
(Source: RecapWhenNotInUse)
Fata Morgana of a ship off the coast, location unknown.(Source: Frimmbits)
Fata Morgana of a ship off the coast, location unknown.
(Source: Frimmbits)
Fata Morgana of a ship at sea, location unknown.(Source: Vokkaab [Tumblr.com])
Fata Morgana of a ship at sea, location unknown.
(Source: Vokkaab)
Fata Morgana off the west coast of Arctic Greenland, in Kane Basin.© Dave Walsh
Fata Morgana off the west coast of Arctic Greenland, in Kane Basin.
© Dave Walsh
Fata Morgana, or superior mirage of Joe Island, off the west coast of Arctic Greenland, in Nares Strait, near Petermann Glacier.© Dave Walsh
Fata Morgana, or superior mirage of Joe Island, off the west coast of Arctic Greenland, in Nares Strait, near Petermann Glacier.
© Dave Walsh

And lastly, because I’m a scientist… SOURCES:

National Snow & Ice Data Center
Astronomy.org
Leifi Physik
Atmospheric Optics
Smithsonian Magazine (Actually…  awesome article about the Titanic – read it!)
NASA Atmospheric Picture of the Day

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