Rotating ice discs seen on a small creek near Palmer, Alaska, January 2013
I’ve shown you some cool ice discs on the River Ice photo Blog in a couple of earlier posts, but here’s a new twist on that phenomenon. Brian Miller took these photos on a tiny creek near Palmer, AK while snowmobiling earlier this week. Click this link if you would like to see a little video clip of this. As the video shows, the ice pans were swirling around in the opening due to an eddy in the flow here.
These photos and video likely depict the early stages of ice disc formation. Notice how the some of the smaller frazil pans are moving together? This is because they tend to freeze together to form rafts. You can also see how they have been grinding against the intact ice; this rounds the opening and the edges of the pans themselves. As more and more frazil pans get trapped in the eddy, they will eventually all freeze together forming one large spinning raft. This rotating raft will also have its edges ground smooth as it rotates within the opening – eventually creating one large spinning disc.
Thanks Brian for sharing these great photos and video with us!