Here a practical link for optical calculations like Brewster angle


Thanks for the feedback.
I had not heard of Brewster's angle.
I will need time to consider these suggestions.


On Fri, Aug 11, 2023 at 3:11 PM MSF <> wrote:

    We call them "colors" down here south of the border, Harry. But to
    your question, yes I have experienced the same phenomenon. Keep in
    mind that peripheral vision is more light sensitive than foveal

    I can think of two possibilities to explain the phenomenon. Light
    from the clear sky is partially polarized along a north to south
    axis. So if you are walking in a mostly north or south direction
    you would see these colors to your left or right as the angle to
    the area you are observing is around Brewster's angle. They would
    be secondary colors.

    Alternatively, it might just be a very thin oil slick formed from
    the asphalt and you need the more sensitive peripheral vision to
    perceive it.

    More than you wanted to know, probably.

    ------- Original Message -------
    On Wednesday, August 9th, 2023 at 7:36 PM, H L V
    <> wrote:

    This summer I have been walking to work in the morning during
    twilight just before the sun rises.
    As I walk across asphalt paved streets which are old and
    cracking, sometimes I see very faint bands of colour
    in my peripheral vision when I am looking at the pavement. When
    it happens I am walking roughly southward ( at 46 degrees north
    latitude) and the bands seem to appear on the left side of my
    peripheral vision. The colours remind more of those found in the
    Goethe spectrum rather than the rainbow spectrum. I wondered if
    it might be an effect of LED street lighting reflecting off the
    pavement but sometimes it seems to arise far from any LED street
    lights. Has anyone else experienced this?


Jürg Wyttenbach
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