Caustics: Light and a Glass of Water; Our Sun and Our Atmosphere

Photographer: Photography Class, Southern Maine Community College Summary Author: John Stetson    

Caustics are a significant element in the composition of Andre Kertesz’s 1917 photo, “Underwater Swimmer.” Though often seen in shallow streams and pools, caustics can be found whenever rays of sunlight intersect and converge, resulting in areas of enhanced brightness.

To let my students directly observe caustics, a glass of water was placed in sunlight (top photo). Another place to see "caustics" is in the sky (bottom photo, taken on October 10, 2013, from near Portland, Maine). 

Portland, Maine Coordinates: 43.6591, -70.2568

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Caustics in the Virgin River, Utah