A superior mirage occurs when an image of an object appears above the actual object, this phenomenon appears in the Arctic because of the weather condition – temperature inversion, where cold air lies close to the ground with warmer air above it. Cold air is denser than warm air, so it bends light towards the eyes of people standing on the ground, modifying how distant particular object appears. Superior mirages can result in few different types of images: distant objects may seem to float higher than their actual position (e.g., a boat can look like it is floating in the sky), or a distant object can become visible.
It is possible that mirages helped sailors on Arctic waters to find out what was below the horizon. The first Celtic explorers of Iceland may have sailed on small leather – covered boats because of Faroe Islands mirage, 385 km from Iceland.