Blog post: Bill Angel: Visualizing "rainbows" in ice on the surface of a pond.

This image was created by photographing the ice on the surface of a pond. The patterns displayed here are not visible to the naked eye. They become visible when the camera's lens is equipped with a polarizing filter that only allows light to reach the film that was reflected by the ice at one particular angle of polarization. To enhance the color contrasts of the polarized light, air was injected under the surface of the ice. This air layer, besides adding to the aesthetic interest of the images,causes more of the light incident on the ice layer to be reflected back to the surface, rather then being transmitted through the ice layer into the water underneath. Other images created using this same technique can be viewed here

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