Pressure ridge (ice) in the context of "Drift ice"

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⭐ Core Definition: Pressure ridge (ice)

A pressure ridge is a linear pile-up of sea ice fragments formed in pack ice by accumulation in the convergence between floes in an oceanic or coastal environment.

Such a pressure ridge develops in an ice cover as a result of a stress regime established within the plane of the ice. Within sea ice expanses, pressure ridges originate from the interaction between floes, as they collide with each other. Currents and winds are the main driving forces, but the latter is particularly effective when they have a predominant direction. Pressure ridges are made up of angular ice blocks of various sizes that pile up on the floes. The part of the ridge that is above the water surface is known as the sail; that below it as the keel. Pressure ridges are the thickest sea ice features and account for up to 30–40% of the total sea ice area and about one-half of the total sea ice volume. Stamukhi are pressure ridges that are grounded and that result from the interaction between fast ice and the drifting pack ice. Similar to undeformed ice, pressure ridges can be first-, second-, and multiyear depending on how many melt seasons they managed to survive. Ridges can be formed from ice of different ages, but mostly consist of 20–40 cm thick blocks of thin and young ice.

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👉 Pressure ridge (ice) in the context of Drift ice

Drift ice, also called brash ice, is sea ice that is not attached to the shoreline or any other fixed object (shoals, grounded icebergs, etc.). Unlike fast ice, which is "fastened" to a fixed object, drift ice is carried along by winds and sea currents, hence its name. When drift ice is driven together into a large single mass (>70% coverage), it is called pack ice. Wind and currents can pile up that ice to form ridges up to dozens of metres in thickness. These represent a challenge for icebreakers and offshore structures operating in cold oceans and seas.

Drift ice consists of ice floes, individual pieces of sea ice 20 metres (66 ft) or more across. Floes are classified according to size: small – 20 metres (66 ft) to 100 metres (330 ft); medium – 100 metres (330 ft) to 500 metres (1,600 ft); big – 500 metres (1,600 ft) to 2,000 metres (6,600 ft); vast – 2 kilometres (1.2 mi) to 10 kilometres (6.2 mi); and giant – more than 10 kilometres (6.2 mi).

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Pressure ridge (ice) in the context of North Pole

90°N 0°E / 90°N 0°E / 90; 0

The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is the point in the Northern Hemisphere where the Earth's axis of rotation meets its surface. It is called the True North Pole to distinguish from the Magnetic North Pole.

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Pressure ridge (ice) in the context of Geographic north pole

The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is the point in the Northern Hemisphere where the Earth's axis of rotation meets its surface. It is called the True North Pole to distinguish from the Magnetic North Pole.

The North Pole is by definition the northernmost point on the Earth, lying antipodally to the South Pole. It defines geodetic latitude 90° North, as well as the direction of true north. At the North Pole all directions point south; all lines of longitude converge there, so its longitude can be defined as any degree value. No time zone has been assigned to the North Pole, so any time can be used as the local time. Along tight latitude circles, counterclockwise is east and clockwise is west. The North Pole is at the center of the Northern Hemisphere. The nearest land is usually said to be Kaffeklubben Island, off the northern coast of Greenland about 700 km (430 mi) away, though some perhaps semi-permanent gravel banks lie slightly closer. The nearest permanently inhabited place is Alert on Ellesmere Island, Canada, which is located 817 km (508 mi) from the Pole.

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Pressure ridge (ice) in the context of Stamukha

A stamukha (plural: stamukhi; from Russian стамуха) is a grounded accumulation of sea ice rubble that typically develops along the boundary between fast ice and the drifting pack ice, or becomes incorporated into the fast ice.- see also NSIDC. It is a pressure ridge. Wind, currents and tides contribute to this phenomenon. Stamukhi tend to occur in belts that are parallel to the shoreline, along coastal shoals, at water depths of about 20 m (65 ft), but that can reach 50 m (160 ft). They can build up to heights 10 metres (33 ft) or more above the waterline. Although they remain pinned to the seabed, these features can be subject to small displacements, either due to thermal expansion or to the pressure exerted by the drifting pack ice onto the fast ice. Because stamukhi tend to be deeply grounded, they may occur as isolated ice features in the open sea during the summer season, after the surrounding ice has melted away.

Since stamukhi extend downward into the seabed, they present a risk to submarine pipelines and telecommunications cables that cross the shoreline. Seabed penetration by the ice can reach a depth of 5 metres (16 ft).

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Pressure ridge (ice) in the context of Cape Columbia

Cape Columbia is the northernmost point of land of Canada, located on Ellesmere Island in the Qikiqtaaluk Region of Nunavut. It marks the westernmost coastal point of Lincoln Sea in the Arctic Ocean. It is the world's northernmost point of land outside Greenland. The distance to the North Pole is 769 km (478 mi).

As the northernmost point of Canada, Cape Columbia is exposed to the ice drift of the Arctic sea ice. The approximately 2 m (6 ft 7 in) thick pack ice of the Arctic Ocean moves several hundred metres per day from east to west. As a result, mighty ice pressure ridges can be piled up at Cape Columbia.

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