Colored Spider Webs

I'm a nature photographer, please excuse my mangling of any physics terms or concepts. Recently I captured images of a spider web displaying rainbows as light passed through it. I have been trying to understand exactly why this is caused, the best explanation I have read was that the web acts as a diffraction grate. However, in my research I found in most photos of this phenomenon the colors in the spider webs were fairly faint. In the spider web I was photographing, the colors were very bright and prominent. In this particular instance the light was also passing through standard window screening on our outside patio before it hit the web, and I photographed it in the first two hours of the day, towards the sun. My questions are, is the diffraction grate description of the web accurate or is their another effect occurring? Does the window screening also have an effect on the light to create the brighter colors, and from a physics standpoint just what is occurring to the light? Here is a link to a video of the web as well as to a gallery of images. I know there is always a question in photography about the use of Photoshop, in this case there was very minimal processing via Photoshop done. Thanks for any information you have to offer on what is occurring in this!Video: https://youtu.be/0oqNPAOQeA8Photo Gallery: http://www.jasonhahn.com/collection/photography/rai-rainbow-spider-web/Thanks,Jason
- Jason Hahn (age 43)
34638

Your video makes it clear that this is some sort of diffraction effect, with the apparent colors shifting around as the web bends in the wind. I was coming up with nothing trying to think what little objects on those web fibers could have the right sort of spacing to form an effective diffraction grating. Fortunately a quick web search turned up:

https://www.itp.uni-hannover.de/~zawischa/ITP/spiderweb.html 
https://www.itp.uni-hannover.de/~zawischa/ITP/spiderweb.html

They say " The colours are caused by interference of the rays scattered by the arrays of tiny sticky droplets on the catching threads". So apparently some types of spider deposit these tiny droplets in a very regular pattern.

Mike W.

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(published on 02/08/2017)