Mirages Mirages are optical phenomena caused by the refraction of light through heated air rising from a sandy or stony surface. They occur in the interior of the desert about 10 kilometers from the coast. They make objects that are 1.5 kilometers or more away appear to move. This mirage effect makes it difficult for you to identify an object from a distance. The mirage effect makes it hard for a person to identify targets, estimate range, and see objects clearly.
Mirages make land navigation difficult because they obscure natural features.
You can survey the area at dawn, dusk, or by moonlight when there is little likelihood of mirage. Light levels in desert areas are more intense than in other geographic areas. Moonlit nights are usually crystal clear, winds die down, haze and glare disappear, and visibility is excellent. You can see lights, red flash-lights, and blackout lights at great distances. Sound carries very far.