Photographers have many tools available to them for directing and shaping the light used to make an image. I think, however, any photographer would be hard pressed to duplicate the complex curves found in a snow drift shining in the sun. Deep snow is such a near perfect reflector of light that any deviation from a direct reflection angle results in noticeable light or dark areas. This scene gave me a chance to play around with continuous variation in tones across different areas:
The wind blowing over the fence in the background drives the snow across a growing pile of previously fallen snow. Heavier/larger flakes settle out of the airstream and land on the ground, becoming a foundation for progressively lighter/smaller flakes to attach to and drop out of the wind. Eventually the snowpile gets large enough to interfere with the wind, creating pressure differences on the windward vs. leeward faces. At the single digit temperatures we’ve experienced small snowflakes essentially act like grains of sand, climbing the windward face and streaming away from it as the wind blows them hard enough to move but not sufficient to dislodge them. This “snowflake creep” continues, building a leeward shelf as the wind pushes more and more flakes up the slope and out onto the shelf.
Interesting physics from a material standpoint but my interest is more in the optics going on across both faces. As the low sun hits these frozen waves it gets reflected onto itself where the curvature of the snow concentrates the light, such as under the shelves, resulting in an area of light brighter than the surrounding snow and looking like an extra light is shining in there. Falling across the top of the shelf at a low angle the sun is not reflected back but instead travels away from the viewer, rendering the top of the shelf darker than the surrounding snow. That fine line marking the edge of the shelf separates two zones of contrast; the lower reflects light toward the viewer, the upper directs light away.
For me photographing snow is the most basic lesson in observing tonal differences in light on subjects – and one of the more frustrating compositions I work on. The fine granular nature of the snow is very hard to capture in an image yet it is a quality integral to the scene when you’re standing there. It takes very shallow angle light to capture that level of fine detail, which in this scene would unfortunately mean losing the range of tones that are so interesting. So, for this image, the white areas are just blank, serving as a backdrop for the more interesting math functions portrayed by the waves.