That said, we ended up with a somewhat disturbing photo7 as it apparently contradicts the conclusions and reasoning presented! It shows a small colored arc, which relative to the observer is visible almost vertically and on the side of the sun, in addition having the concavity facing upwards - the opposite of everything said above!

• To find an explanation for this phenomenon, it is helpful to look closely at a photograph of the sun in direct backlight, taken on the same occasion. There is hardly any breeze, the surface of the water is a mirror and you can clearly see the strong reflection of the sun on the water. It is this reflected light and not direct sunlight that causes the phenomenon photographed and, therefore, it is easy to verify that everything agrees with the adaptation of the previous considerations to this special situation!

7 It was taken in the Aveiro estuary, near Torrão do Lameiro, on 26 October 2014.