|Tin Hat Mirage
Green flashes and a highly distorted sunset imaged by Rick Albrecht from Florida.
©Rick Albrecht, shown with permission.
Rick uses a 1100mm F/7 lens/scope extended to 2200mm to capture unusual sunsets from Blind Pass between Sanibel and Captiva Islands, Florida.
A temperature inversion, abnormally cooler air beneath warmer, is necessary to produce the mirage. Sun rays are refracted downwards towards the ocean by the temperature gradient between the two air layers. The rays produce an inverted slice of the sun beneath the ‘normal’ image. Rays passing deeper into the inversion layer produce a third erect image closest to the horizon.
If the temperature inversion gradients are strong enough the ray bent toward the ocean can travel for long distances around the curvature of the Earth. This ‘ducting’ often produces highly flattened sunset mirages. It is possible that the Florida mirage was produced by a very thin duct close to the ocean surface. In that case the line is an extremely flattened image of the whole solar disk.