I don't know. I have seen something like that when the sun reflected into the pinhole. One of my cameras has a 1/4" drilled hole in the side of a can, and the pinhole is taped inside the can. The edges of the 1/4" hole are shiny, and a glint of sun can reflect directly onto the pinhole. It causes something similar.
The exposure in the 2nd one looks very good.
I like UV reflection in the air or mist, but I don't think it could be that strong.