Development of new ice

When sea water is freezing, it initially forms ice crystals called frazil. Frazil develops into an oil-like mixture of ice crystals and sea water, which is called grease ice. In calm conditions, further cooling will form an elastically solid ice cover up to 10 cm thick [Carsey, 1992, p. 10]. This ice cover is known as nilas. On the other hand, the presence of wind and waves will form masses of ice, which develops circular shapes, when they are bumping together. This is called pancake ice, and the individual pancakes normally grow in diameters of 30-300 cm [Carsey, 1992, p. 10]. Slush is formed in the open water areas between the pancakes, and on further freezing, the slush consolidates, forming a solid field of pancake ice.
Over time, a consolidated ice cover is referred to as first year ice. It has a high brine content and generally a smooth surface. In the subsequent summer melt period, brine drainage reduces the brine concentration, and a low saline ice with air voids is produced. This is known as multi year ice.