Illumination of an Old Spider Web
November 29, 2011
Photographer: David Lynch; Dave's Web sites: 1, 2
Summary Author: David Lynch
A daddy longlegs spider (Pholcus phalangioides) had built a chaotic web in my office window that was reshaped by insects flying into it. The drooping filaments folded delicately over themselves, with stray wisps and strands around it. Lovely all by itself, as the Sun rose and shined on the web, it displayed many different contrasts. At first, the web was in shadow and its silhouette was dark against the bright sky (main picture and upper right). When the Sun hit it, the web lit up brightly, even against the sky (next small picture down). By moving slightly, I could view the web against the dark hillside (next small picture down). For context, the small picture on the lower right shows the web in my window -- the main patch of the web is about four inches (10 cm) long.
Spider silk is very fine (a few micrometers thick) and scatters light efficiently. Sometimes there are bright colors, especially when backlit and viewed against a dark background. Whether the web is “dark” or “bright” depends on the illumination and background against which it's viewed. The same is true of thin clouds, dust, hair and other material that's largely transparent. Sun angle and background can make big differences in the way things look. Photo taken on November 7, 2011 in Topanga, California.