Please note: You are viewing the unstyled version of this website. Either your browser does not support CSS (cascading style sheets) or it has been disabled. Skip navigation.

Dispatch 23: The Many Faces of Sea Ice

   Print Change text to small (default) Change text to medium Change text to large

Alex Kain

October 9, 2009

Water is the only substance on earth that naturally occurs as a liquid, a solid, and a gas. Its appearances are many. In liquid form, water appears as the dark gray of the North Sea and the spectacular green of the Caribbean. Vapor, in its varied forms, composes stratospheric clouds, San Franciscan fog, and disorienting desert mirages.

Yet when it comes to shape shifting, ice is the superlative transformer of the natural world. Ice can exist as huge and dense bergs, or ephemeral and delicate snowflakes. In the Arctic, ice appears in manifold shapes, colors, and sizes. But from the smallest frost flower to the most massive glacier, it’s all the same substance.

The following images offer a brief summary of ice forms encountered thus far on the CCGS Louis S. St-Laurent.

Meringue Elegant

Snow Cover. Looking like the stiff peaks of a meringue pie, these chunks of sea ice accumulated after currents and winds pushed floes together and pieces fell to the ice’s surface. Once the piles formed, snow covered all exposed surfaces, giving the pieces a soft, whipped appearance.

Cleaving. Pure, clean, and sleek, a flat, a snow-covered ice sheet cleaves as the ship breaks through, cracking open like a geode to reveal a vibrant interior of blue multi-year ice. Ice’s crystal structure allows it to break along linear ridges, much like jewels.

Meringue Elegant

Frost Flowers. These tiny ice crystals, known as frost flowers, occur when individual water molecules in the air freeze to each other. The molecules, seeking a lower state of kinetic energy, move from the air to the colder surface of the ice forms. The larger frost flowers in this image are roughly the size of a pea.

Frost. Best known as the nuisance that requires you to scrape your windshield when it’s still freezing outside, frost is the accumulation of ambient water vapor molecules across an exposed surface. When frost buildup occurs at a rapid rate, as it did three days ago on the Louis, ice formations begin to differentiate and produce frost flowers. Pictured here are a vent and a door handle covered in frost, which accumulated on the ship overnight when temperatures plunged below -20 degrees Celsius.

Icicle Icicle 2

Icicles. These stalactites of the aquatic world form in freezing environments when liquid water drips down ice suspended to a surface. Icicles attach to built structures like the side of the Louis, and also to elements of the natural environment, like these thin spears forming off the underside of a floe. Though they look still and elegant, if a large icicle breaks and falls off the roof ledge of a building, it can easily kill a person.

Color Unifcon

Color. Don’t let the white snow cover deceive you. Sea ice comes in an array of magnificent hues. The color of ice comes from its ability to refract blue hues of sunlight. Color is perhaps the best indicator of ice’s age. Younger pieces are cloudy and white, owing to imperfections like brine content and air channels that cause the ice to reflect white light. Older ice is bright blue in color, owing to its uniform crystal structure that better refracts blue wavelengths of light.

Sastrugis and pattern. Sea ice cover can provide a flat, uniform surface on which wind and snow create uniform shapes. These sastrugis, or dumpling-shaped snow forms, extended into the horizon. When the ship breaks through the ice sheets, seawater erupts with color and ice chunks break into pieces of similar size.

Color Unifcon

Ridges. When ice on either side of a crack is forced together under compressive stresses, one sheet will subduct, and one will form a ridge. This ridging pushes large pieces onto the surface of ice sheets that then pile up and form masses that look like Frank Gehry’s interpretation of Stonehenge.

Finger rafting. As two thin ice sheets respond to forces like wind and current that push them together, they can intersect, interlock, and form a zipper-like pattern in a phenomenon known as finger rafting. The right angles produced by finger rafting stand out in an environment dominated by sensuous curves and acute, sharp angles.

All text and photos property of Alex Kain.

Last updated: October 7, 2019

whoi logo

Copyright ©2007 Woods Hole Oceanographic Institution, All Rights Reserved, Privacy Policy.
Problems or questions about the site, please contact