Friday, April 21, 2017

Quételet Scattering

As I was driving along one recent morning I spotted this.

Well not exactly, as I made the video after turning around and going back to drive by again. I then pulled over and walked back to take some pictures (no surprise there huh?).

Above is what I saw while driving up.

It wasn't obvious from the video, but as we can see in the images, the colors were pretty intense as they flashed by.

The images below give a hint to what's going on (as always, click on an image to bigafy it).

Look closely and you'll see a layer of dust on the water surface.

This dust scatters the light such that some is scattered prior to reflecting off the water surface and some is scattered after reflecting off the water surface. The light rays are thus out of phase resulting in interference which manifests to our eyes as colors.

Of course, the Atmospheric Optics site has a full explanation, complete with diagrams. And you might enjoy learning about Adolphe Quételet, who figured this out, as well.

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