Three white hang glider shaped objects in clear blue sky flying in a circle, counter clockwise moving in and out of a tight formation.3 white hang glider shaped objects traveling in a circle, like a slightly tilted farris wheel. The objects moved in and out of a loose triangle to a very tight triangle formation. As the objects kept cirlcling counter clockwise, at the 12:00 position the furtherest 2 objects would completely dissapear, then as they reached the 10:00 position, they would reappear again. I don't know if they could have been some kind of kite? If this had been at night or any place else I would have thought maybe they were advertising something, but there is NOTHING around to advertise. Also, for some reason, as I was intently watching these strange objects I never once mentioned to my husband what I was seeing. He may have noticed them, but if so, he isn't the type to admit it or talk about it. What I saw has been on my mind for over a month now so I decided to report it. Also, because of the mountains and hills I couldn't tell if they were small objects close by, or large objects far away. Also difficult to tell if they were large and very high in the clear blue sky, or small and low. This was my first time in the Hat Creek, Lasson National park area, so maybe this is something common that I am not familiar with, I just don't know.((NUFORC Note: Witness elects to remain totally anonymous. Description seems to be not inconsistent with sailplanes, gliders, or hang-gliders thermalling in a tight thermal, but that is only a possibility. PD))