Whether falling through the air or as a layer on the ground snow is made up of mostly air space. As light reaches snow, there are so many points for it to be reflected that no single wavelength is absorbed or reflected with any consistency. Almost all of the white light from the sun hitting the snow will reflect back and still be white light. Therefore, snow appears white. (http://weather.about.com/od/winterweather/a/snow_white.htm)
Fiona Williams works somewhere between photography and painting. Untitled (snow-white) is a compilation of new work exploring presence, or a sense of something that is at once brightly pointed and strangely muted.