The fact that ice floats is one of its most amazing and important properties. There are very few other materials on Earth, and none as abundant as water, that expand as they solidify so that the solid form becomes less dense than the liquid form. The source of this remarkable trait is at the molecular level and how the electric charge surrounding the two hydrogen atoms and the oxygen atom that comprise the water molecule is distributed. This leads to a more open crystal structure in ice, as opposed to the denser packing of water molecules in liquid water. The structure of the water molecule and its arrangement in the solid also gives rise to the spectacular six-fold symmetry of snow flakes.
The buoyancy of ice is such a well-known phenomenon that it is easy to forget its importance. The world would be a vastly different place if ice sank to the bottom of the sea, where it would accumulate and fill the ocean basins. In our floating-ice world however, the ice remains on the surface where it modulates global climate by reflecting solar energy and insulating the waters beneath. It also provides a habitat and platform for a wide range of organisms and is used as a travel corridor by man as well. In the Floating Ice Group, we study a broad range of subjects with global implications that all arise from the peculiarities of the water molecule.
Visit the Sea Ice Group website.