Ice with everything - Antarctica: Global Science from a Frozen Continent - page 68

Figure 3.1 Antarctic ice velocity derived from satellite radar interferometry. Thick black lines

delineate major ice divides. Thin black lines outline subglacial lakes. Thick black lines along the
coast are ice sheet grounding lines. (Credit: Rignot, E., J. Mouginot and B. Scheuchl (2011).
Ice flow of the Antarctic ice sheet. Science , 333 , 1427-1430)

temperature and thus delays the formation of sea ice. The initial ice is called
frazil ice and its formation usually takes place in bays where the effect of wind is
limited. As the air temperature continues dropping below

20 C,

' '

sea ice forms
in situ . This 2.5 cm thick soft ice is fractured by the tidal movements: when the tide
rises, the expansion of the ocean surface creates ice cracks; when the tide falls, the
decrease of the ocean surface generates an overlap of the slabs of ice at the edges.
Near the shores, pancake-ice is formed when slabs of ice are jostled by the winds
and waves and curl upwards at the edges. They can reach a thickness of 0.50m.

fast