This phenomena occurs most every year right behind our house on the Androscoggin River in Gorham, NH. There is a small eddy and at the right time of year and with perfect conditions (foam and ice crystals floating down the river) they spin off to the eddy, develop a core and it grows and grows. When I first saw it, I thought someone had thrown paper plates into the river. I have an older photo of one disk that I pulled out and photographed on the river bank. And I have several recent videoclips also, if you are interested.

My earlier photos I sent to the weather man at WMUR and the Boston ABC station and also some weather phenomena site (can't recall the name).