Heat shimmer

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Heat shimmer from the engine exhaust of a Lockheed SR-71 A.
Heat shimmer over fire.

Heat shimmer (also known as air shimmer ) is a phenomenon of atmospheric optics and is caused by the formation of streaks that vary over time due to rising layers of air at different temperatures, and thus different air densities , over hot surfaces. The refractive index of the air changes due to the fluctuations in air density . At the boundary layers of differently heated air masses, the light is refracted differently , which can then be perceived as heat shimmer.

This phenomenon can also occur if - for example in the case of ice and snow - different air densities arise due to cooling effects.

A typical example is driving on an asphalt road in summer. The poor visibility caused by the shimmering air may make obstacles on a road invisible.

Turbulence is essential for the flicker. If reflections occur in layers of air with different refractive indices, one speaks of a mirage .

See also

Individual evidence

  1. ^ Jearl Walker: The Flying Circus of Physics: Questions & Answers . 8th edition. Oldenbourg, Munich a. a. 2000, ISBN 3-486-25478-2 , pp. 264 .