A mirage is a phenomenon where you think you see water. In this picture it looks as though these mountains are reflected in a lake. There might not even be mountains there at all.
Mirages are most common in deserts. They happen when light passes through two layers of air with different temperatures. The desert sun heats the sand, which in turn heats the air just above it. The hot air bends light rays and reflects the sky.
When you see it from a distance, the different air masses colliding with each other act like a mirror. The desert ahead seems to have become a lake but it is actually a reflection of the sky above.
Mirages can be seen almost anywhere – those shimmering heat hazes that appear on the road ahead of you on sunny days, but disappear as you approach are mirages.
In the countryside you may seem to see a small lake or pond near trees or in a field, this is also created by differences in temperature between the ground temperature and the air just above ground level.
A beautiful mirage called the Fata Morgana appears in the Straits of Messina, between Sicily and Italy. It is an image of a town in the sky, like a fairy tale landscape. It is believed to be a mirage of a fishing village situated further along the coast.