Moon Mirage

Last Sunday's (6th May '12) super large moon rising over New Zealand.   Shot by Andrew Drawneek from 1100m on the side of Mt. Taranaki. Image ©Andrew Drawneek, shown with permission.
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The moon changed shape over a few tens of seconds. As it climbed over the landscape, ripples and indents slid from top to bottom .

A piece has broken off in the top image made 38s after the pinched moon at right.

The rising moon was viewed through multiple temperature inversion layers – horizontal air layers unusually warmer than those immediately below. The layers are usually stable and quiescent rather than turbulent. The upper boundary of the main layer is very faintly visible at right (slightly below the large pinch). At lower right the moon has climbed sufficiently that its rays are no longer passing through the main layer boundary.

Air is insubstantial. The moon’s or sun’s rays must traverse it almost horizontally to be significantly refracted between layers at slightly different density (it is density gradients rather than temperature differences themselves that refract).

The need for grazing incidence restricts sun/moon distortions and mirages to within a few degrees above the horizon.

Similarly, the distortions are upwards or downwards. The frequently reported "double suns" or moons with a secondary image to the side are invariably caused by viewing or shooting through windows.