Antarctica Glossary of terms A - H
ablation - The removal of material from
a glacier, melting, evaporation, or calving (bits dropping
off the end into the sea to form icebergs). Opposite of
ablation zone - That portion of a glacier where more material is lost (by melting or evaporation) than gained by snowfall.
abyssal plain - The deep ocean plain, a relatively flat part of the ocean floor lying at depths between 3500 meters (11,480 feet / 2.2 miles down) and greater than 6000 meters (19,680 feet / 3.7 miles down). This region is dark, cold (and very gloomy) subject to little or very slow water movements and very stable.
accumulation - The addition of material
to glaciers, snow, rain, material blown by wind, and avalanches.
Opposite of ablation.
accumulation zone - The region of the glacier where mass is only added (as snow or rain), no mass is lost. Usually this area is near the origin of the glacier at higher altitudes.
albedo - How reflective a surface is.
High albedo means that much of the incoming radiation is
reflected (for example snow and ice); low albedo means that
much of the incoming radiation is absorbed (for example
algae - A plant group that compose the majority or all of the phytoplankton in bodies of water, mostly unicellular though there are multicellular forms such as kelp. Algae can form lichens in a symbiotic relationship with fungi. Usually neglected when the plant groups are listed, algae are responsible for more than half of all photosynthesis on earth.
Antarctic Bottom Water - The coldest and densest water mass in the global oceans. Formed in particular places on the Antarctic continental shelf such as Weddell Sea and Ross Sea when surface water cools and becomes more dense and so sinks to the ocean floor. Once formed it tends to flow northwards hugging the seafloor. It can be traced into many ocean basins, including parts of the North Atlantic Ocean.
Antarctic Circumpolar Trough - An atmospheric feature located between 60°S and 65°S. A zone of low pressure that causes variable winds moving from west to east and responsible for the "Screaming sixties" as known to seamen.
Antarctic Convergence (Polar Front) - A surface boundary where which the colder, north flowing Antarctic Surface Waters sink beneath warmer circulating waters. This marks a change in the oceans surface temperature and also chemical composition. North of the convergence, the area is known as the sub-Antarctic.
arid - Very dry. An area with little
rain or precipitation of any kind (snow, hail, sleet etc.)
usually less than 25 centimetres (10 inches) of annual rainfall,
Antarctica is largely classed as arid.
arthropod - A group of invertebrates with hard exoskeletons and jointed limbs such as insects, spiders, and crustaceans (shrimps, crabs, lobsters).
atmosphere - The gases that surround a planet. Earth's atmosphere consists of about 20% oxygen and 79% nitrogen with smaller amounts of other gases. "Atmosphere" is also used as a unit for the measurement of pressure. One atmosphere equals 14.7 pounds per square inch being the pressure due to the mass of the gases acting on the earth at sea level.
atmospheric circulation - Movement within the atmosphere, winds and air currents, caused by differences in pressure from one region to another. Air moves from a region of high pressure where it is concentrated to "thinner" areas of low pressure.
atmospheric pressure - The amount of pressure exerted by the atmosphere at a given point (force per unit area). Essentially the effect of the mass of the air above a particular point being pulled down by gravity
atmospheric sciences - The study of
the atmosphere, of the envelope of gases that surround the
Earth. Atmospheric science include meteorology and climatology.
aurora - The display of "dancing" light patterns seen in areas of high latitudes - nearer the poles. Auroras are caused by magnetic storms from the sun releasing huge amounts of energy. The energy travels toward the Earth as an ionic cloud. On reaching the earth, the cloud "blows" over the poles and interacts with Earth's magnetic field. The ions interact with the ionosphere energize oxygen and nitrogen molecules which causes them to emit light.
Anything in the northern hemisphere is referred to as "Boreal", in the southern hemisphere as "Austral", hence Aurora Borealis in the north and Aurora Australis in the south.
avalanche - A mass of snow and/or ice detached from where it rested and slipping down a slope.
axis - An imaginary line through the centre of the Earth, around which the planet rotates.
bacteria - A group of acellular microscopic organisms, bacteria are found everywhere. Different types may be involved in the decomposition of organic matter, in making food by photosynthesis, in the guts of all multicellular organisms, in the deepest ocean and in Antarctica, even living inside rocks as protection from the elements.
Beaufort scale - A way of measuring the strength of the wind given as a number or "force":
|Beaufort wind scale|
|Speed mph||Specifications for use on land||Specifications for use at sea|
|0||Calm||0 - 1 mph||Smoke rises vertically||Sea like a mirror|
|1||Light air||1 - 3 mph||Direction of wind shown by smoke drift, but not by wind vanes.||Ripples with the appearance of scales are formed, but without foam crests.|
|2||Light breeze||4 - 8 mph||Wind felt on face, leaves rustle, ordinary vanes moved by wind.||Small wavelets, still short, but more pronounced. Crests have a glassy appearance and do not break.|
|3||Gentle breeze||9 - 13 mph||Leaves and small twigs in constant motion, wind extends light flag.||Large wavelets. Crests begin to break. Foam of glassy appearance. Perhaps scattered white horses.|
|4||Moderate breeze||14 - 19 mph||Raises dust and loose paper, small branches are moved.||Small waves, becoming larger; fairly frequent white horses.|
|5||Fresh breeze||20 - 25 mph||Small trees in leaf begin to sway, crested wavelets form on inland waters.||Moderate waves, taking a more pronounced long form, many white horses are formed. Chance of some spray.|
|6||Strong breeze||26 - 32 mph||Large branches in motion, whistling heard in telegraph wires, umbrellas used with difficulty.||Large waves begin to form, the white foam crests are more extensive everywhere. Probably some spray.|
|7||Moderate gale||33 - 41 mph||Whole trees in motion, inconvenience felt when walking against the wind.||Sea heaps up and white foam from breaking waves begins to be blown in streaks along the direction of the wind.|
|8||Fresh gale||42 - 50 mph||Breaks twigs off trees, generally impedes progress.||Moderately high waves of greater length, edges of crests begin to break into spindrift. The foam is blown in well-marked streaks along the direction of the wind.|
|9||Strong gale||51 - 61 mph||Slight structural damage occurs (chimney-pots and slates removed).||High waves. Dense streaks of foam along the direction of the wind. Crests of waves begin to topple, tumble and roll over. Spray may affect visibility.|
|10||Storm||62 - 74 mph||Seldom experienced inland; trees uprooted, considerable structural damage occurs.||Very high waves with long over- hanging crests. The resulting foam, in great patches, is blown in dense white streaks along the direction of the wind. On the whole the surface of the sea takes on a white appearance. The 'tumbling' of the sea becomes heavy and shock-like. Visibility affected.|
|11||Violent storm||75 - 91 mph||Very rarely experienced; accompanied by wide-spread damage||Exceptionally high waves (small and medium-size ships might be for a time lost to view behind the waves). The sea is completely covered with long white patches of foam lying along the direction of the wind. Everywhere the edges of the wave crests are blown into froth. Visibility affected.|
|12||Hurricane||92 + mph||The air is filled with foam and spray. Sea completely white with driving spray; visibility very seriously affected.|
bedrock - General term for the underlying rock layer in a region.
benthic - Benthic organism live at the bottom of a body of water such as sea, river, lake etc. These organisms are sometimes referred to collectively as the "benthos".
bergschrund - The crevasse formed where a glacier meets the solid rock of a mountain slope, usually very wide and the widest crevasse on the glacier.
beset - The situation of a ship when
closely surrounded by ice on all sides.
biota - All of the living organisms of an ecosystem or an area, plants, animals, bacteria, fungi etc.
black ice - Newly-formed iced over sea water. It is thin enough for the dark water to be visible through it and can be crossed only at speed by a light sledge.
blizzard - A cold storm with winds of at least 56 kilometres per hour (35 miles per hour) and temperatures below - 6.7°C (20°F). Usually also characterized by poor visibility due to snow blowing around. Little snow may actually fall during a blizzard, the high winds pick up snow from the ground and carry it around, visibility is often greatly reduced.
brash ice - Ice rubble, loose pieces of ice of various sizes from gravel to table sized. Originates from sea-ice that is breaking up or commonly as debris from calving ice bergs or ice bergs that break up as part of their ongoing erosion. Whenever one large piece of ice falls off another, brash is also generated and can cover quite large amounts of sea. There were times in Antarctica when we would gather brash ice that had blown into the cove where our base was to melt down and use as fresh water. The ice usually came from ice bergs that had broken up off shore, with the wind blowing it onshore.
breakable crust - A dreadful surface over which to travel. A layer of snow that has hardened on top and sunk below. Walking across such an area means that you lift your foot and place it as for a normal step, but just a few inches higher, it takes most of your weight, but as you lift your weight onto it, at the last second the crust breaks and you're standing there with both feet a few inches below the surface crust. As much effort as walking up stairs just to stay on the level, going up hill is doubly hard.
calve - The formation of an iceberg from a glacier. Once the ice flowing from a glacier reaches a body of water it begins to float and may crack at the "hinge zone", once free of the glacier a piece of ice becomes an iceberg and the glacier has calved.
cirrus clouds - Thin, wispy high altitude
clouds that form at heights of 6 to 12 kilometres (3.8 to
climatology - The study of weather conditions over long periods of time.
commensal - Plants and / or animals living together and gaining benefit from the relationship. Generally a fairly loose bond and not as intimate as a symbiotic relationship.
congelation ice - A type of sea ice
that forms underneath established sea ice.
continental shelf - The region in the ocean around a continent between the shoreline and the continental slope. An area of shallow water where the depth is usually less than 200 meters (650 feet) - shallow is a relative term here. In Antarctica however, the continental shelf averages 500 meters in depth (1640 feet)! The continental shelf has formed by slow deposition of sediment eroded from the continent and has a gentle slope (around 1°).
continental slope - Narrow, steep (3° to 6° slope) transition zone between the shallow shelf and the deep ocean floor.
Coriolis effect - moving objects appear to deflect from their anticipated straight-line course. Coriolis effect is a result of the rotation Earth (and an observer's position on it). Responsible for the fact that water spirals down a plug-hole rather than going straight and the direction is different in each hemisphere. Only at the equator does water go straight down.
crevasse - A deep, usually vertical,
crack or split in a glacier, occurs as a result of the brittle
ice flowing over a uneven surface beneath the ice. Crevasses
can easily become covered by blown snow, even very wide
ones. Great care must be taken when crossing ice and snow
fields to avoid them as falling down one is really going
cryosphere - That portion of Earth's surface that is permanently frozen through the year.
cyanobacteria - Very specialized acellular organisms classified as blue-green algae. Cyanobacteria can photosynthesize, making their own food from sunlight. They are exceptionally tough organisms, able to colonize and survive in harsh environments.
Dead man - an anchor board buried deep in snow to secure sledge or night span of sled dogs. Br.
desert - An area where there is little moisture due to there being little precipitation is low and evaporation is high. Precipitation usually is less than 25 centimetres a year (10 inches). Large deserts include the Sahara Desert in Northern Africa or the continent of Antarctica.
diatoms - Single celled planktonic algae with external skeleton made of silica. The skeletons, or tests, of dead diatoms sink to the sea floor and accumulate in the sediment. If sufficient quantities of skeletal material accumulate, a diatomaceous mud (10% diatoms) or diatomaceous ooze (>30% diatoms) results. The chlorophyll from the diatoms may give it greenish tinge. There is a continuous belt of diatomaceous ooze a round Antarctica.
diversity - The variety of different
characteristics, features or organisms. The variety of species
in a given region or the number of different species in
a particular place. High diversity usually means a more
stable and less easily disturbed ecosystem.
downwelling - In oceanography, the replacement of deep waters by surface waters moving down because of a change in temperature or more rarely salinity. Downwelling may bring waters rich in oxygen to the deeper parts of the ocean or lake.
draft - The distance below the water
level (sea level) the bottom of an iceberg reaches. In some
cases, icebergs are blown into shallow waters by storms
and the bottom ploughs into the ocean causing the iceberg
to get stuck. Draft also refers to how far below the water
line the keel of a ship reaches and so determines how close
into shore the ship can go.
East Wind Drift (Antarctic Coastal Current) - Westward flowing ocean surface current that flows anti-clockwise around Antarctica, driven by the polar easterlies.
easterlies - Winds that blow from the east (yup-really). The polar easterlies blow close to the continent and help move the ocean surface currents known as the east wind drift.
ecology - The study of the abundance of organisms in an ecosystem and the relationships between the organisms and their environment.
ecosystem - A particular environment, large or small, with characteristic physical conditions and types of organisms living there.
elevation - The height of an object or
area above a particular reference point, usually the height
above sea level.
evaporation - Change in state from a liquid or a solid to a gas. Evaporation takes place most quickly in an arid or dry environment when there is little or no water vapour in the air. Antarctica is arid and solid ice can "evaporate" or turn into a gas, particularly if a (relatively) warm wind blows across a snow or ice field. The change from a solid directly to a gas is properly called sublimation - like the "smoke" you get when you open the freezer door.
extraordinary Katabatic wind - Katabatic wind that is particularly long-lasting (days to even weeks) and remains fairly constant in strength during that time.
fast ice - Sea ice that forms in situ along the coastline and remains attached or fast in the nautical meaning of the word.
fauna - Animals. Antarctic fauna includes seals, penguins, whales, krill, ice-fish, nematode worms, mites, and wingless midges (plus a few other animals). Also sometimes used in the phrase "charismatic mega-fauna" large animals with charisma - penguins, seals, whales etc.
finnesko - Boots made entirely from
fur including the sole. Originally an Inuit item of clothing,
no longer in use, much used in the heroic age of Arctic
and Antarctic exploration. Packed with sennegrass, a dried
grass for additional insulation.
firn - A transitional stage between snow and glacial ice, a type of snow that has survived a summer melting season and has become more compact than freshly falling snow.
fissure - A long, very deep, narrow
opening, sometimes used instead of crevasse.
fjord (fiord) - A long, narrow, steep-walled, u-shaped coastal inlet. Fjords typically have been excavated by glaciers.
flora - Plants. Fairly limited in Antarctica, mainly mosses.
frazil ice - Ice crystals in the water column, usually near the water surface. Frazil ice crystals are not oriented in an organized manner, and have the appearance of slush or separated needles, diving through frazil ice you can see that below the main body, the crystals are quite large and separate. The first stage in the formation of sea ice.
frost smoke - Condensed water vapour that forms as a mist above any open sea water in very cold weather.
Fulltrack - a snow vehicle with tracks, i.e. Muskeg tractor. Br.
gale - A strong wind. On the Beaufort Scale - used to gauge the speed of the wind, a gale has winds of 39 to 46 miles per hour (62 to 74 kilometres per hour). Gales can break twigs off trees (not that you can tell in Antarctica) and make walking very difficult. Gales are common in Antarctica.
geology - The study of Earth, the history of the rocks, what processes that have occurred and are occurring on and within it (to the rocks).
geomagnetic pole - If the Earth's molten metallic core is imagined to be a giant bar magnet, the Geomagnetic Pole is where you would expect the magnetic field lines to converge. But ocean currents, mountains and solar activity mess things up, similar to how a compass can be confused if you hold it near something metal. Because of this while the geomagnetic pole is where the needle of a compass should point straight downwards, it is the magnetic pole where this is actually the case. The Magnetic Pole can move many kilometres in a day, whereas the Geomagnetic Pole moves much more slowly.
The geomagnetic poles aren't fixed and wander about,
currently the south geomagnetic pole is about 1160 kilometres
(725 miles) north (think about it) of the south geographic
pole (close to the Russian Vostok Station).
With thanks to Glenn Grant - 60South.com
geophysics - The study of the physical properties of Earth as a planet. Geophysicists may study the interior of the Earth, the geomagnetic field of the Earth, or the Earth's gravity field. Most of the work is done using very high tech equipment and requires much translation to be understood by standard humans.
geothermal - Geo - earth, thermal - heat. Heat generated within the interior of Earth. Visible indications of geothermal activity are geysers when underground water comes into contact with a heat source, such as hot rocks near a volcano. In Antarctica, Deception Island is geothermally active, there are also thought to be several regions on the continent where glaciers are melted from below by geothermal heat making them flow more quickly.
glacial erosion - The wearing down of the Earth's surface by glaciers. Rock debris at the bottom of a glacier scrapes and erodes the surface over which the glacier flows like a giant hugely heavy piece of sand paper.
glaciation - The formation, activity,
and retreat of glaciers through time. The glaciation of
a region refers to the growth of ice over that region. Large
parts of the Northern Hemisphere experienced glaciation
in the past - ice ages.
glacier - A river of ice. Usually a mixture of ice, air, water, and rock debris formed at least partially on land. They are large enough for the ice to flow with gravity. Glaciers can be small valley glaciers, ice streams, ice caps, and ice sheets. The term glacier also includes ice shelves if they are fed by glaciers. Made of freshwater ice.
glaciology - The study of the physical and chemical properties of snow and ice, not necessarily just of glaciers. Glaciologists might study the movement of ice sheets, and how ice flows. Also the study of how snow slowly changes to glacier ice.
glaze - A smooth, clear coat of ice.
grease ice - A thin layer of ice crystals beginning to show organization on the water surface with a greasy appearance and like a slush puppy in consistency.
grounding line - The point a glacier that is flowing into a sea or lake loses contact with seafloor and begins to float as an ice shelf.
Hanging valley - A u-shaped valley that joins the wall of a larger valley. The smaller valley floor "hangs" above the larger valley floor. Hanging valleys are made by valley glaciers carving out a path, when the glacier was active the smaller valley glacier would have flowed into the larger valley glacier.
Heat reservoir - Places where heat is absorbed and then distributed slowly to the surroundings. Oceans and other large bodies of water act as heat reservoirs. They absorb heat and slowly pass it to the atmosphere. This is one reason why coastal areas and islands never get as cold as areas inland in winter. The heat doesn't have to be very great, the sea can still seem very cold, as long as it is above the surrounding air temperature, heat will be transferred.
Highs (high pressure zones) - Places
where the the atmospheric pressure is above the surrounding
region. Clear weather often accompanies high pressure systems.
Hoarfrost - A light, feathery ice coating built up from water particles in the air crystallizing out into tiny ice sculptures (you have to look carefully).