Light effect at sunset at Merville

Once again I was able to see the green flash from the beach at Merville in Normandy. On this particular night I was unconvinced but I did film it to try to catch the moment. Reviewing the film has brought out a detail that I missed. There is a clear V shape in the light, 10 degrees up from the surface of the sea on each side.Maybe it was about particular conditions that night. I have not yet found an explanation.