The Superior Mirage
The superior mirage can make objects appear to be floating in the air or cause objects actually located below the horizon to appear above it (remember the setting-sun example), a condition called looming. The figure above shows an example in which we apparently see a sailboat floating in the air. Superior mirage images often appear inverted. The superior mirage can also make objects appear to be taller than they actually are, a condition called towering.
Superior Mirage causing "towering" of sailboat.
The superior mirage is as common in cold polar regions as the inferior mirage is in the hot deserts and is known as the arctic mirage or hillingar in Icelandic. There is ample evidence to suggest that arctic explorers may have discovered new lands because they saw mountains looming above the western ocean horizon that were actually pack ice or small icebergs altered by superior mirage conditions to appear as coastal mountains. Some historians believe the voyages of Erik the Red to Greenland and his son Lief Erikson to North American shores were undertaken because they believed they had seen great lands and mountains to the west, visions produced by persistent and strong superior mirages. (For more on the Arctic Mirage, click here.)
Superior Mirage allows sight beyond the horizon.
Scale is greatly exaggerated.
When the air temperature increases from the surface at a rate of 11 Celsius degrees per 100 metres, the Earth's horizon will appear flat. As the inversion becomes stronger, the horizon edge will continue to rise from the flat position. When the inversion gradient reaches 18 C deg/100 m, the observer will have the illusion of being in a saucer -- that is, the horizon appears as if turned upward.
Mirages also have their playful side -- inverting images of ships at sea and hanging them in mid-air, or constructing dancing fairy castles over the waters, the Fata Morgana. In a Fata Morgana mirage, distant objects and features at the horizon appear as spikes, turrets or towers, objects with great vertical exaggeration rising from the surface.
Charles Earle Funk of Funk & Wagnell's Dictionary fame traced the origin of Fata Morgana to Italian poets who named what they saw rising up across the Strait of Messina after the fairy castles of Morgana. Literally, Fata Morgana means the Fairy Morgana, a reference to the English legends of King Arthur's enchanted sister Morgana, who dwelled in a crystal castle
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