WITH PHOTO - Walker 'stunned' to see ship hovering high above sea off Cornwall

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.

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.

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