Kangastus

Kangastus is a Finnish term that refers to a visual phenomenon, most commonly experienced as a mirage. Mirages are optical illusions caused by the bending of light rays in layers of air with different temperatures and densities. The most frequent type of kangastus observed in Finland is the inferior mirage, where a distant object, such as a lake or a road, appears to have a shimmering reflection below it. This effect is often seen on hot, sunny days when the ground heats up the air directly above it, creating a layer of warmer, less dense air. Light rays passing from the sky or a distant object through this warm layer are refracted upwards, creating the illusion of a reflection.

Superior mirages are also possible, though less common. In these instances, the object appears to be displaced upwards, sometimes elongated or even inverted. This type of kangastus typically occurs when there is a temperature inversion, with cooler air near the surface and warmer air above. Light rays passing through these layers are bent downwards, making the object appear higher than it actually is. Kangastus can be observed in various environments, including over bodies of water, deserts, and even flat, open land. The term is also sometimes used more broadly to describe any striking visual distortion or illusion, though its primary association is with atmospheric optical phenomena.