Hourglass shape of sunlight reflected on the sea

 

Mrs B pointed out that the line of reflected sunlight narrows to a neck coming away from the Sun but widens again as it gets near us. If the Sun was a small point source of light in the sky, the light should spread out in a wedge towards us. My best guess is that the Sun is spherical and rays are coming in at different angles. If there are waves at the correct angle, they can redirect rays that were spreading out and down back in our direction. The spreading nearer to us would then be the normal point source phenomenon. Now we've noticed it, we need to see if it repeats and under which circumstances.