Approximately circular, floating pads of ice, often with raised rims. The pads form through the aggregation of slush in the water, either derived from falling snow or present as frazil ice. Collisions with neighbouring pads are responsible for both the circular shape and the rims, where the slush deforms plastically on impact. Splashes of water assist freezing to consolidate both the disks of ice and the rims.
Subjects: Meteorology and Climatology.