A Guide To Ice In The Ocean

Water freezes in many different crystal patterns and ways in the different seas and locations. Information about these different types, and how ships and boats deal with them.

To mariners, ice has many different forms. Certain kinds of ice can stop a boat in its tracks. Other kinds of ice give the ocean an oily appearance and reflect certain parts of the daytime or night sky. Oceanic ice, in all its forms, almost constitutes a science in itself. This article is about the kinds oceanic ice, and their effect on boats and the ocean's surface.

Oceanic ice can be a day or several years old. New ice is ice that has recently formed on the ocean's surface, first-year ice is ice that has existed for one year, Old ice is ice that has passed the one-year mark. Depending on its age, ice can be anywhere from half an inch to 40 feet thick, in the case of icebergs. Ice contains many different states of formation within these categories.

Young ice exists in many forms. It can be thin and covering the surface like an oil sheet, or thicker and slushy, as in the case of Nilas and pancake ice. When ice first begins to form, it often undergoes "frazillation," or the formation of small plates of ice just under the surface of water. Frazil ice is often deceptive, because it gives the ocean a slick, oily feel. In several cases it has been mistaken for an oil spill. When frazil ice hardens, it turns into slush, or a thicker, water-based form or semi-solid snow. When slush congeals into spots on the surface of waves, these are called "shuga" due to their resemblance to powdered sugar. Nilas ice is a very interesting form of new ice. It is a thin crust of ice that moves with waves. It's surface is covered with interlocking snowflake of "finger" patterns, and this allows the ice to move easily, even in storms. Pancake ice is a harder form of Nilas ice. Pancakes of ice form when slush or Nila ice congeals into larger cakes on the surface of the water. When these cakes crash into each other, pieces of ice get stuck to other pieces, and the cakes grow larger. This form of ice is sometimes rather dangerous to ships, because of the size this ice can attain. If pancake ice rips apart or is torn for any reason, in large quantities, it can become brash ice, or broken ice, in the water.



Ice takes on forms past this young ice stage. Ice can exist in floes, or very large flat pieces of ice. (Smaller floes are also pancakes, or pancake ice.) Ice floes have the ability to travel and to remain still, which makes them an interesting adversary to boats. Spaces of clear water in between floes are called "leads," because they allow a boat to make its way father into icy territory. Ice can also exist in the form of icebergs, or large chunks of ice in the water. Icebergs are not pieces of frozen ocean. They are huge pieces of glaciers, that have melted and fallen into the water. To be an iceberg, a piece of ice must measure 5 meters above the surface of the water. Underwater, icebergs can extend up to 100 feet! Icebergs are incredibly dangerous to both submarines and ships, because of their size and their capacity for sharp edges.

In general, ocean ice can be broken apart, ridged, level, bumpy or new. Ice can also be gray or pure white, depending on its age and the water that it is made of. In general, the thicker the ice, the whiter it appears. Icebergs tend to have a bluish quality because of their shape and the fact that they are glacier-made.

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