a ship floating high in the air
The weirdest mirage you'll ever see: a ship floating high in the air
https://projectavalon.net/floating_ship_mirage.jpg
https://www.theguardian.com/science/...tical-illusion
Walker 'stunned' to see ship hovering high above sea off Cornwall
David Morris encounters rare optical illusion known as superior mirage while out on coastal stroll
There are only so many polite words that come to mind when one spots a ship apparently hovering above the ocean during a stroll along the English coastline.
David Morris, who captured the extraordinary sight on camera, declared himself “stunned” when he noticed a giant tanker floating above the water as he looked out to sea from a hamlet near Falmouth in Cornwall, SW England.
The effect is an example of an optical illusion known as a superior mirage. Such illusions are reasonably common in the Arctic but can also happen in UK winters when the atmospheric conditions are right, though they are very rare.
The illusion is caused by a meteorological phenomenon called a temperature inversion. Normally, the air temperature drops with increasing altitude, making mountaintops colder than the foothills. But in a temperature inversion, warm air sits on top of a band of colder air, playing havoc with our visual perception. The inversion in Cornwall was caused by chilly air lying over the relatively cold sea with warmer air above.
https://projectavalon.net/superior_mirage.png
Because cold air is denser than warm air, it has a higher refractive index. In the case of the “hovering ship”, this means light rays coming from the ship are bent downwards as it passes through the colder air, to observers on the shoreline. This makes the ship appear in a higher position than it really is – in this instance, above the sea surface.
“Superior mirages occur because of the weather condition known as a temperature inversion, where cold air lies close to the sea with warmer air above it,” said David Braine, a BBC meteorologist. “Since cold air is denser than warm air, it bends light towards the eyes of someone standing on the ground or on the coast, changing how a distant object appears.”
Photographers around the world have captured striking images of ships, yachts and other vessels apparently hovering in mid-air thanks to superior mirages. One potential clue that the sight is a mirage is the lack of any detail below the vessel’s waterline – for example a mirage of a “hovering” yacht lacked the lower hull and keel.
The latter effect is well known to sailors who can sometimes rely on refraction to spot ships that are geometrically beyond the horizon. Sailors say such ships are “looming” over the horizon and sometimes report distortions that stretch or compress the images, making them “towering” or “stooping” mirages, respectively.
