Mirage is a natural phenomenon, the result of which appear imaginary visible images of different subjects. They arise due to total internal reflection of light in the atmosphere with an unusual distribution of air vertically.
Mirages are stable and wandering, horizontal and vertical. Are even special cards caravan routes, where there are places where there are mirages. In these maps is denoted by, where there are wells, palm groves, buildings, oases, mountain chain.
Very often the victims of mirages are the travelers in the desert of Erg er-Ravi. Before people are awake, seemingly near, appear oases, which are actually not less than 700 miles. For example, 360 km from the oasis of bir-Ula victim Mirage was the caravan, which was led by an experienced guide; 60 people and 90 camels, followed by Mirage, died. Mirage drew them aside 60 kilometers from the Holy well.