Humidity is the los angeles type=LOW. As I said, I repositioned the neg to the other side of the frame and the rings show up on the same spot on the print.
Your probably getting rings elsewhere, they're just getting printed over. The stuff is all guesswork, and it is a maddening problem. I'll hold forth that the glass, the pressure, or the humidity in some combination are the problem. I used to get them here, and it doesn't get much drier. Went away for me when I went to a frame with more pressure.