Göran Strand of Östersund, Sweden wrote:
The height of a rainbow depends on the height of the sun. When the sun is high in the sky we get a low rainbow and when the sun is low in the sky we get a higher rainbow.
In this picture taken by sunset, when the sun is at its lowest, the rainbow is the highest. With the reflection in the water you see that there is a perfect circle, this can only happen at sunset. If the sun was higher in the sky, we would have seen the rainbow and the reflection had the shape of an ellipse.
Outside the primary rainbow, it’s possible to suspect the secondary bow. It was a little more visible during shorter periods, but then the water wasn’t as cool.