The theme park people say it is a ring of smoke from their volcano ride. The ring stays perfectly stationary as clouds drift past it. It doesn't float up, it doesn't move with the wind, it doesn't dissipate. Some smoke ring footage included below for comparison.
Possible UFO Caught on Video
Original footage
here.
Some images of a ring shaped UFO from Fort Belvior in 1957 .
Ring shaped UFO over Orlando FL in 1999 .
Smoke ring at Bonnaroo .
Smoke ring at Burning Man .
Smoke ring from a volcano .
Totally unrelated: fun with .
Enjoy!