That dark ring. The only rings you get like that are the 22 1/2 degree rings you get around a light source like the sun or moon in diffused misty light......except it's light, not dark. It is caused by internal refraction and reflection in water drops and appears as a ring- especially noticeable with a full moon and light cloud some nights. I guess this one is 'dark light'! Every time I look at this picture it becomes more fake.