We spent the week in Berwick upon Tweed, the most northerly town in England. The caravan park was on a hill above the estuary, looking back across to the town and out to sea. I began to notice that the sea looked different shades of blue, depending on which direction you looked relative to the Sun. That got me thinking about how we see things. The picture above is Berwick by night. We only see the luminous objects that make light, and a few that reflect light ( you might make out the arches of the railway viaduct). Below is a picture from the oldest bridge, looking into the Sun. It is obvious that we see the river because it reflects sunlight. The light patch at the bottom of the picture is a true reflection of the Sun in the "angle of incidence = angle of relection" sense, but I'm still thinking about the bright patch at the top of the picture. It must be a reflection of the Sun, but the angles don't quite work...
This picture of the viaduct is taken with the Sun behind me. You can see that it reflects sunlight back at us directly because it looks bright, and that sunlight reflects from it onto the water and up to our eyes. So to some extent, the river is lit up by reflections from elsewhere. It's just that, when I stop to think about it, not all of the angles seem to make sense.
