Within the ice

Ice formation

Figure 2) the formation of frazil ice

Frazil ice (fig 2) forms first on the surface of the seawater as long as it is below the freezing point of water. The ice crystals are only 3-4mm. The next stage in the freezing process occurs as the frazil crystals begin to coagulate to form a thin soupy layer called grease ice due to its resemblances to an oil slick (Horner et al. 1992). The freezing process in a calm sea, with no wind or waves present, the ice crystals start to freeze together forming a uniform sheet, called Nilas ice. If the process occurred in more turbulent then ice forms into circular pieces known as pancake ice. The pancakes start to raft together due to pressure pushing them atop of each other to from an ice sheet.

Ice growth begins to slow down, and instead of more frazil ice being formed columnar crystals grow on the underside of the ice producing congelation ice (Lange et al. 1989). This is mainly due to the lower temperature causing the ice crystals to become elongated. TheĀ greatest growth of the columnar is in waters of low turbulence. This is one of the distinguishing features between the two Polar Regions as the Arctic is far less turbulent so columnar ice can be up to 60-80% of the total pack ice. In comparison the Antarctic, which is much more turbulent in nature than the Arctic, frazil ice plays a much bigger role in the formation of ice with taking up to 80% of the pack ice (Thomas 2008).

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