An immense natural mirror
The mirages at Lake Gairdner are a direct result of physics acting on a massive scale. The phenomenon is an example of an inferior mirage. On a hot, sunny day, the white salt crust absorbs solar radiation, heating the layer of air directly above it. This creates a sharp temperature gradient, where the air at the surface can be more than 10°C hotter than the air just a meter above. Hot air is less dense than cool air and has a lower refractive index.
As light from a distant object, like a speeding car or the sky itself—travels toward an observer, the rays that pass close to the ground enter this superheated, less-dense layer. This causes the light rays to bend, or refract, upwards in a gentle curve. The human brain, which assumes light travels in straight lines, interprets these upward-curving rays as if they are coming from below the ground. This creates an inverted, shimmering image directly below the real object, giving the illusion of a reflection in water or, for moving cars, the appearance of flying above a phantom surface.