Image: Nilas Sea Ice1

Description: Nilas Sea Ice Buffin Bay Arctic. In calm water, the first sea ice to form on the surface is a skim of separate crystals which initially are in the form of tiny discs, floating flat on the surface and of diameter less than 2-3 mm. Each disc has its c-axis vertical and grows outwards laterally. At a certain point such a disc shape becomes unstable, and the growing isolated crystals take on a hexagonal, stellar form, with long fragile arms stretching out over the surface. These crystals also have their c-axis vertical. The dendritic arms are very fragile, and soon break off, leaving a mixture of discs and arm fragments. With any kind of turbulence in the water, these fragments break up further into random-shaped small crystals which form a suspension of increasing density in the surface water, an ice type called frazil or grease ice. In quiet conditions the frazil crystals soon freeze together to form a continuous thin sheet of young ice; in its early stages, when it is still transparent, it is called nilas. When only a few centimetres thick this is transparent (dark nilas) but as the ice grows thicker the nilas takes on a grey and finally a white appearance.
Title: Nilas Sea Ice1
Credit: Own work; The image was taken from an icebreaker
Author: Brocken Inaglory
Usage Terms: GNU Free Documentation License
License: GFDL
License Link: http://www.gnu.org/copyleft/fdl.html
Attribution Required?: Yes