Fast ice may be more than 1 year old and may then be prefixed with the appropriate age category old, second-year or multi-year. Fast-ice boundar y. The ice boundary at any given time between fast ice and pack ice. Fast-ice edge. The demarcation at any given time between fast ice and open water.
First-year ice. Sea ice of not more than one winter's growth, developing from young ice, with a thickness of 30 centimeters to 2 meters. Any relatively flat piece of sea ice 20 meters or more across. Floes are subdivided according to horizontal extent. A giant flow is over 5. A massive piece of sea ice composed of a hummock, or a group of hummocks frozen together, and separated from any ice surroundings. It may float showing up to 5 meters above sea level. Old snow which has recrystallized into a dense material.
Unlike snow, the particles are to some extent joined together; but, unlike ice, the air spaces in it still connect with each other. Frazil ice. Fine spicules or plates of ice, suspended in water. Glacier ice. Ice in, or originating from, a glacier, whether on land or floating on the sea as icebergs, bergy bits, or growlers.
A coating of ice, generally clear and smooth but usually containing some air pockets, formed on exposed objects by the freezing of a film of super cooled water deposited by rain, drizzle, fog, or possibly condensed from super cooled water vapor. Grease ice. Ice at that stage of freezing when the crystals have coagulated to form a soupy layer on the surface. Grease ice is at a later stage of freezing than frazil ice and reflects little light, giving the sea a matte appearance.
Grounded ice. Floating ice which is aground in shoal water. It extends less than 1 meter above the sea surface and its length is less than 20 feet 6 meters. A growler is large enough to be a hazard to shipping but small enough that it may escape visual or radar detection. A hillock of broken ice which has been forced upwards by pressure. It may be fresh or weathered. Hummocked ice. Sea ice piled haphazardly one piece over another to form an uneven surface.
When weathered, hummocked ice has the appearance of smooth hillocks. A massive piece of ice greatly varying in shape, showing more than 5 meters above the sea surface, which has broken away from a glacier, and which may be afloat or aground. Icebergs may be described as tabular, dome shaped, pinnacled, drydock, glacier or weathered, blocky, tilted blocky, or drydock icebergs. For reports to the International Ice Patrol they are described with respect to size as small, medium, or large icebergs.
A whitish glare on low clouds above an accumulation of distant ice. A narrow fringe of ice attached to the coast, unmoved by tides and remaining after the fast ice has moved away. Land sky. Dark streaks or patches or a grayness on the underside of extensive cloud areas, due to the absence of reflected light from bare ground.
A fracture or passage-way through ice which is navigable by surface vessels. Beset in the ice with the surrounding ice forcibly pressing against the hull. Old ice. Most topographic features are smoother than on first-year ice. Open pack ice. Pancake ice. Predominantly circular pieces of ice from 30 centimeters to 3 meters in diameter, and up to about 10 centimeters in thickness with raised rims due to pieces striking against one another. It may be formed on a slight swell from grease ice, shuga, or slush or as a result of the breaking of ice rind, nilas, or under severe conditions of swell or waves, of gray ice.
It also sometimes forms at some depth, at an interface between water bodies of different physical characteristics, from where it floats to the surface; its appearance may rapidly cover wide areas of water.
A non-linear shaped area of water enclosed by ice. All highlights. Glaciers and icebergs represent two of the most important facets of Earth's ecosystem, accounting for Arctic and Antarctic glaciers, icebergs, and other ice trivia Glaciers and icebergs represent two of the most important facets of Earth's ecosystem.
Still, glaciers and icebergs are far more vital than even this statistic indicates. Image by Jamie Scherbeijn What really is the difference between glaciers and icebergs?
No, it's not a Seinfeld bit. It's actually a very common question. Image by Mark Vogler The underrated importance of icebergs and glaciers Another reason glaciers and icebergs are vital to the rest of the planet is because glaciers continually grow and release icebergs into the Arctic and Antarctic seas.
Without glaciers and icebergs, many of those critical rivers and lakes would dry up. How glaciers and icebergs contribute to quence your thirst The majority of Earth's water is saltwater, which is undrinkable.
You can thank them best by recycling that plastic. Tip of the iceberg not just an Arctic or Antarctic saying Have you ever heard someone say, "The tip of the iceberg"? How Arctic and Antarctic glaciers get their colorful texture As glaciers grow, they accumilate sediment from the ground and volcanic materials from the air.
Explore the glaciers and icebergs of Antarctica and the Arctic When you head out on an Arctic trip or expedition cruise to Antarctica, you won't be able to help noticing how beautiful and multiform these regions' glaciers and icebergs are.
Title image by Melissa Scott. Share this article:. Related cruises. Ross Sea Incl. Cruise date: 14 Jan - 16 Feb, The rest is trapped and becomes multi-year ice or perennial ice, averaging around 7 years old, and m thick, compared to first year ice at m thick. Because of the salt content, seawater begins to freeze at about —1. Ice formation begins at the surface with the formation of small needle-like ice crystals called frazil , which accumulate and make the water appear slushy and cloudy; this stage is referred to as grease ice Figure In calmer water these small crystals can freeze together into a thin surface layer called nilas , which can reach a thickness of up to 10 cm Figure Wave action can break up the nilas into small mats m across, which then bump into each other and form rounded shapes with raised edges, called pancake ice Figure If temperatures remain cold the pancake ice freezes together into solid ice floes , a hard surface covering the ocean Figure Ice floes then freeze together into ice fields.
Once ice floes form, the water underneath becomes insulated and heat loss to the atmosphere declines, so the water no longer cools and no more ice formation occurs. As a result, young sea ice is usually relatively thin, not more than m thick. The ice can get thicker through precipitation; there is not a lot of precipitation at the poles, but due to the low temperatures, whatever does occur tends to accumulate rather than melt.
Over time the accumulated ice and snow can add to the overall thickness of the sea ice, but it will still never approach the thickness of glacial ice.
As sea ice crystals form, most of the salt is excluded, so sea ice contains much less salt than seawater, and can be melted for drinking if needed. As ice forms and salts are excluded into these pockets, the salinity of the remaining water increases and it can become too salty to freeze. These unfrozen pockets of briny water make sea ice a little softer and more slushy than fresh water ice, which is harder and more rigid. For example, cm of fresh water ice is enough to support the weight of a single person, but you would need at least 15 cm of sea ice to do the same.
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