Maine’s giant, spinning ice disk is taking shape again. In 2019, it reached about 91 meters across, rotating slowly in the Presumpscot River. How exactly these features form is still a matter of debate, but scientists have worked out a few relevant mechanisms. The spinning of the disk seems to depend on a vortex that forms beneath the ice as melting water sinks. (One of water’s peculiarities is that it’s densest around 4 degrees Celsius, so newly melted water is actually denser than ice. Otherwise ice wouldn’t float!) The plume of sinking water sets up a vortex that drags the ice disk with it as it spins in the river beneath. (Image credit: R. Bukaty/AP; via Gizmodo)
Tag: ice disk
Enormous Ice Disk
We’ve seen spinning ice disks before, but this month Westbrook, Maine has developed the largest one I’ve ever seen. A research paper from 2016 indicates that this seemingly alien formation spins due to an oddity of water. Water is at its densest around 4 degrees Celsius, so as the ice of the disk melts in the warmer waters of the river, it sinks. That downward plume sets up a vortex in the water beneath the disk. And as the water spins, it drags the ice with it, causing the disk’s rotation. The warmer the water is, the faster the disk spins. (Image credit: T. Radel/City of Westbrook; research credit: S. Dorbolo et al.; via Gizmodo; submitted by jpshoer)
