on some of the shots the flash did go off and it was the built in flash. that might be some of it. some of the pictures at the last bridge also had orbs but the flash was off and the humidity lower (late afternoon).
there were some strange things going on at the last bridge outside of the pictures. the first bridge was at 9:30 am an still a lot of frost melting.
the first bridge was mostly taken into the sun. maybe that had something to do with it?