Pack Ice Term used in a wide sense to include any area of sea ice, other than fast ice , no matter what form it takes or how it is disposed. It may be formed on a slight swell from grease ice , shuga or slush or as the result of the breaking of ice rind, nilas or, under severe conditions of swell or waves, of grey ice . The pancakes start with a diameter of tens of centimetres, but through wind and wave action they aggregate with loose frazil crystals to increase in diameter, and raft with other pancakes to increase in thickness. In this manner the pancakes can rapidly grow to a few metres in diameter and up to 1 m thick. Eventually the pancakes can freeze together into larger floes or a consolidated ice cover.
Pancake ice can rapidly cover vast areas within the pack.
The characteristic upturned edges of the pancakes result from continuous collisions. Small pancakes welding together to form larger floes. Polynya Any non-linear shaped opening enclosed in ice. Sometimes the polynya is limited on one side by the coast and is called a shore polynya or by fast ice and is called a flaw polynya. If it recurs in the same position every year, it is called a recurring polynya.