Glass bead bow

While at work I was on break time I took some blast sand out of the sand blaster and scattered it on the ground and I happened to look down and saw a bright bow around the head of my shadow. The bow is like a rainbow but the higher refractive index of glass made a bow with a radius of 28 degrees rather than 42 for a water drop rainbow. Look for these glass bead bows on reflective signs and freshly painted black top.

Posted by Michael Ellestad

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Posted on May 13, 2011, in rainbow and fogbow, theory and tagged , , . Bookmark the permalink. 7 Comments.

  1. Les Cowley said…

    Nice bow Michael. The radius of glass bead bows is about 21 degrees, depending on the type of glass.

  2. Peter-Paul Hattinga Verschure said…

    I sometimes see strongly spectral-colored light patches in sun-lit backgammon-boards which are provided of a special reflection structure. But I never saw a real bow shape, and still certainly not in road surfaces. Although I am a dyed-in-the-wool cyclist. Obviously there always remain chances to see new things!

  3. Marko Riikonen said…

    Michael, your work breaks are very productive. Nice shot.

  4. Michael Ellestad said…

    21 degrees? I always thought it was 28 I need to revise that on my homepage. In some ways Les it reminds me of the road paint bow I got in the smokey MTNS in 2003 when new road edge lines were being painted

  5. Les Cowley said…

    28° – Yes, for some reason that figure is also stuck in my mind. I just happened to be preparing the diagram for Gunther””s seawater bow when I read yours and had to go away and double check!

  6. Les Cowley said…

    Michael – I””ve mailed a little spreadsheet to compute rainbow angles. Glass of n~1.5 will be nearer 22-23 deg.

  7. Michael Ellestad said…

    Yeah I got it but I don””t have MS Spreadsheet I have MS word only

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