Superior mirage, time-lapse sequence. The sequence runs from left to right, showing the development of a superior mirage. At left there is no mirage. As the mirage develops the water tower seems taller. A superior mirage, also known as a Fata Morgana mirage, is an optical phenomenon caused by light passing through a region where two layers of air at different temperatures meet. This results in distortion of objects in the far distance. Photographed in December 2009, in Turku, Finland.