Antarctica Glossary of terms I - Z
A B C D E F G H I K L M N O P R S T U W Z | Antarctic Slang
ice blink - A brightness on the horizon,
showing in the clouds above it caused by reflection of sunlight
from sea ice even in overcast conditions, such a sight is often
called an "ice sky". Conversely, a darkness on the horizon when
surrounded by ice denotes the presence of open water and is
called a "water sky".
ice cap - A large
dome-shaped mass of ice that is thick enough to cover all the
landscape beneath it so appearing as a smooth coating of ice.
Ice caps are smaller than ice sheets, usually under 50,000 square
kilometres (19,000 square miles). Ice caps can deform and flow
with gravity and spread outward in all directions. Freshwater.
ice cliff - Walls of ice where glaciers
meet the sea. Ice cliffs occur because icebergs calve from the
front of them giving a continually breaking edge the full height
of the glacier. Freshwater.
ice crystals - Tiny particles of ice that grow on all surfaces when the air is supersaturated with water (cold air doesn't hold much moisture so ice crystals are readily formed in Antarctica). Ice crystals account for the majority of the accumulation of glacial ice on the Polar Plateau. They may also be referred to as ice needles, even though they are not needle shaped. Freshwater.
ice floe - A large, flat, sheet of sea ice that has broken off contact with the coast where it was formed and is floating in open water. Sea-water.
ice foot - A "shelf" of ice that forms around
many Antarctic shores in the winter time. Sometimes formed by
sea spray, often formed where sea-ice joins the land, as the
tide rises and falls, a layer of ice is deposited which builds
up. Once the sea ice blows out in the spring a distinct ledge
several feet high is left behind that can be difficult to cross
for men and also for animals. Sea-water
ice sheet - A large mass of ice that is thick
enough to cover the landscape beneath it so appearing as a smooth
coating of ice. Ice sheets can deform and move with gravity,
they are larger than ice caps. Ice sheets cover much of Greenland
and Antarctica. Freshwater.
ice shelf
- A large flat-topped sheet of ice that is attached to land
along one side and floats in the sea or a lake. Formed where
a glacier or ice shelf has reached the water and kept flowing,
it is fed from the landward side and eroded from the seaward
side by the calving of icebergs and melting. Freshwater.
ice stream - A rapidly moving current
of ice in an ice sheet or ice cap. Ice streams flow more quickly
than the surrounding ice and remove ice from the ice sheet.
Antarctic ice streams may flow about one kilometre per year
(0.6 miles per year). Freshwater.
ice tongue - A long, narrow, projection of ice out from the coastline, similar in origin to an ice shelf, but usually formed where a valley glacier flows rapidly to the sea or a lake. Freshwater.
iceberg - A large piece of floating ice
that has calved, or broken off, a glacier or ice shelf. Icebergs
occur in lakes and the ocean and can be vast, the size of islands
or small countries. Freshwater.
ionosphere
- The electrically-charged layer of the atmosphere that extends
from 80 to 400 kilometres (50 to 250 miles) above the Earth's
surface. The ionosphere absorbs much of the short wave-length
radiation from the sun. As the radiation passes through the
ionosphere, it interacts with nitrogen molecules and oxygen
atoms. These molecules and atoms absorb the radiation, but in
the process they lose an electron (a negatively charged particle)
and become a positively charged ion. The ionosphere is where
auroras originate.
land-based ice sheet - a large body of ice with a base mostly above sea level. The East Antarctic Ice Sheet is a land-based ice sheet. Freshwater.
lapse rate - The change in temperature associated with a change in elevation. When climbing a mountain, the temperature falls approximately 1°C for every 100m in altitude gained.
latitude - Imaginary lines that allow for
the measurement of position north or south of the equator. Latitude
is measured in degrees (one degree - 60 nautical miles, or 111
kilometres). The equator is at a latitude of 0° and the poles
lie at latitudes of 90° north (North Pole) or 90° south (South
Pole). Lines of latitude differ in length according to how far
north and south they are.
lead - Long,
narrow opening or fracture in sea ice. Leads can be useful to
shipping because they do not have to waste fuel and time by
breaking ice, they can be disastrous if travelling over sea-ice
as the path is no longer there. Leads are also useful to seals
and whales that can use them to breathe and for birds that can
feed on marine prey through the lead.
lichen
- Symbiotic association of alga and fungus. The fungus provides
protection and moisture, the photosynthetic algae provide food
for the fungus. Lichens are the toughest form of plant life
and can live in some of the coldest and most exposed places
in Antarctica as long as they have a rock to cling to. They
can actively grow and photosynthesize at well below freezing
point - albeit very slowly.
limnology
- The study of freshwater such as lakes, ponds, and marshes.
The analysis of the physical and chemical characteristics of
the freshwater as well as the plants and animals that live within
them. Antarctic lakes are more affected by climatic and other
changes than is the ocean and so they are seen as giving an
early warning of any impending changes.
longitude
- Imaginary lines that wrap around the Earth intersecting at
the north and south geographic poles. Lines of longitude are
numbered from 0° (the Greenwich Meridian, passing through Greenwich
in London, England) to 180°. Longitudes are called east if they
fall east of the Greenwich Meridian, and west if they fall west
of the Greenwich Meridian. Lines of longitude are all of the
same length.
magnetic storm - Times when the sun radiates large amounts of ions and electromagnetic energy out towards the solar system, tied to sunspot activity. This influx of high energy disturbs the Earth's magnetic field causing interruptions to telecommunications broadcasts and particularly pretty auroras.
marine biology - The study of plants and animals living in the seas and oceans.
maritime - Bordering or next to the ocean
or sea. Maritime climates are oceanic climates, and are milder
than the inland climates because of the moderating influence
of the sea which acts as a huge heat sink absorbing heat in
the summer and giving it out in the winter.
meteorology
- The study of the Earth's atmosphere and the movements
of air and moisture within the atmosphere. Includes the study
of the atmosphere for weather forecasting.
meteorite
- Fragments of rock that reach the Earth from beyond the atmosphere.
Most are believed to come from asteroids, some are believed
to be pieces from other planets. Antarctica is a particularly
good place to find meteorites as they show up against the snow
and ice and are accumulated in some places by the flow patterns
of ice streams and glaciers.
migrate -
Moving from one area to another. Some animals migrate
in certain seasons to find better conditions, such as weather,
food, or for breeding. Many whales migrate to the Southern Ocean
in the summer to feed on the large the quantities of krill for
example.
moss - Small, leafy-stemmed plants that grow in carpet-like mats and tufts on moist ground. Particularly abundant in maritime regions of Antarctica where conditions are too harsh for other types of plant. In Antarctica mosses often accumulate in large "moss banks".
nekton - Free-swimming aquatic animals that move under their own power and can move independently of ocean currents. Whales, squid and many fish are types of nekton.
niche - The life style of an organism, its "job" also - the place in which it lives, what it eats, how it gets nutrients, and the interplay it has with the environment and other organisms.
nip / nipped - a dreaded description of
a ship from the early days of polar exploration when she was
trapped by ice on both sides that was pushing in hard. In contrast
to the gentle sounding nature of the event, the reality was
often that the ship suffered considerable damage or was broken
and sunk.
nunatak - An isolated peak
of bedrock that sticks above the surface of an ice sheet. They
are the peaks of hills and mountains standing above the ice
sheet which flows around them. They offer important information
about ice covered regions as they provide a sample of the rocks
that lie under the ice.
oceanography - The study of the ocean. The
physical properties of the ocean - currents and waves (physical
oceanography), the chemistry of the ocean (chemical oceanography),
the geology of the seafloor (marine geology), and the organisms
that live in the oceans (marine biology and marine ecology).
ordinary katabatic wind - Short-lived katabatic
winds with constant direction but a highly variable speed. Originate
in cold dense air flowing coastward from the high Antarctic
plateau over the pole.
ozone layer - A layer in the Earth's upper atmosphere, the stratosphere that contains almost 90% of the Earth's ozone. This forms a protective blanket against the harmful ultra-violet rays coming form the sun.
pack ice - Often used interchangeably with sea ice. Pack ice is frozen sea that formed somewhere else and has floated to its present position carried by wind, tides and currents. It is broken up and of variable size and thickness, some pieces can be the size of a coffee table and about 1 foot (30cm) thick, other pieces are larger than a tennis court and can be 30ft (9m) or more thick. Usually pack ice is in its second season. Sea-water
Open pack - when the pieces of ice don't
touch
Closed pack - when the pieces of
ice touch
pancake ice - Pancake ice grows from thickened grease ice and resembles pancakes or lily pads. The edges of each piece is upturned because the plates bump into each other as they gently move around in the sea. Usually between about about a foot (30cm) and 6 feet (2m) across. Pancakes tend to be smaller the closer to the shore line they are. Sea-water
physical oceanography - The study of the
physical aspects of the seas and oceans such as the temperature,
salinity, density variation, and the optic and acoustic properties
of the ocean. Also includes the study of nature of currents,
waves, and tides.
phytoplankton - Plant
plankton. Microscopic free-swimming or suspended marine or freshwater
plants within the plankton. Plankton is defined as being those
organisms that inhabit the upper regions of a body of water,
but cannot move about against the influence of water movements
such as currents, they move generally with the water although
may be able to move small distances. Phytoplankton includes
diatoms and other photosynthetic algae, a crucial part of almost
all aquatic food webs.
plate tectonics
- A theory that ties together many observations made about the
activity and movement of Earth's crust (earthquakes, volcanoes)
and creation of ocean basins. Plate tectonics divides the surface
of the globe into a number of rigid plates that move around
the earth's surface over the period of millions of years.
polar - To do with the regions of the north and or south poles of the planet. The poles are cold, icy regions, a polar climate is a cold climate, with average temperatures less than 10°C (50°F).
polar easterlies - Winds that blow from the east as they flow off the high Antarctic polar plateau. Polar easterlies help generate ocean surface currents (east wind drift) in the Southern Ocean.
Polar Front (Antarctic Convergence) - 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.
Polar Plateau - The
relatively flat, high altitude central region of the East Antarctic
Ice Sheet. The plateau has an average height of 2000 meters
(about one mile) above sea level and a smooth surface with a
small slope towards the coast in all directions.
polynyas - A polynya is an area of open
water in pack ice or sea ice, they may be kept open by constant
winds or the upwelling of water and so tend to recur in the
same locations year after year. They are particularly important
for wildlife as they allow mammals such as whales and seals
to have a breathing hole and birds access to the sea in order
to fish.
precipitation - Rain, snow,
hail, sleet etc. moisture falling from clouds to the surface
of the Earth, usually as rain, snow, and ice. The amount of
precipitation is always measured as water or rain equivalent
so allowing for the fact that snow can have various structures
and densities
productivity - A term used to describe the
rate of production in an ecosystem. Extra nutrients usually
increase productivity.
reflectivity - The amount of light or energy that bounces off a surface relative to the amount of light or energy that reached the surface. A mirror is an example of an object with high reflectivity. The ocean has low reflectivity. Reflectivity may also be called albedo.
rookery - A colony of rooks, the term is also used for a colony of penguins.
rotten ice - Old ice, partially melted and often honeycombed
Sastrugi - wind blown snow
picture courtesy
NOAA
sallying a ship - from the early days of polar exploration, causing the ship to roll by crew and passengers running from side to side to prevent adhesion of the ice around her.
sastrugi - Irregular ridges of snow on a
small scale (rarely more than 1 foot, 30cm) that lie parallel
to the direction of the wind. Sastrugi can make travel very
awkward or difficult, they can be quite soft or as hard as ice.
sea ice - A general term for any ice that
forms from frozen seawater. Sea ice covers large parts of polar
waters in the winter and melts back each summer.
sleet - Frozen or partially frozen rain that form when rain passes through a layer of air that is below the freezing temperature, falls to earth as a slush. Freshwater.
South geographic pole - 90°S. The south geographic pole is the southern location where the axis of rotation of Earth intersects Earth's surface.
South geomagnetic pole - The point on Earth's
surface in the Southern Hemisphere where the axis of the Earth's
magnetic pole intersects. The south geomagnetic pole is approximately
1160 kilometres (725 miles) north of the south geographic pole
(think about it). The south geomagnetic pole is tilted about
12 degrees to the axis of rotation of the Earth (geographic
pole).
South magnetic pole - the point
on Earth's surface that a south-seeking compass needle seeks.
At the South magnetic pole a compass needle will point vertically
downwards. This point is currently off the coast of Wilkes Land
and wanders around.
stratosphere - The
layer of the atmosphere that is above the troposphere, it extends
from approximately 10 to 50 kilometres (6 to 31 miles) above
Earth's surface. The upper region contains the ozone layer.
subglacial - Underneath the glacier.
supercooled - A condition when water is
still liquid even though it is at a temperature at which it
normally would freeze. Often under these conditions a small
physical movement a small knock or tap will cause the water
to freeze almost immediately.
tabular iceberg - A flat-topped iceberg, like a table. Freshwater.
terrestrial - Dry land. Terrestrial flora and fauna live on land not in water.
tide crack - Any crack in sea ice that is caused by the rise and fall of the tide. As the tide rises so the area of the sea increases and a crack forms, as the tide falls, so the area decreases and the crack closes. Often form around offshore rocks, between the shore and sea-ice, around grounded ice bergs or even stretching for miles between islands.
tongue - A mass of ice projecting from a glacier into the sea. It is still fixed to and forms a part of the larger glacier. freshwater
trade winds - One of three major circulation
cells in both the northern and southern hemispheres. The trade
winds from approximately 0° to 30° north or south latitude.
Within the regions of the trade winds, prevailing winds blow
toward the west. They were given their name as in the days of
sailing ships, they aided the progress of the ships and hence
the trade of goods carried by those ships.
upper atmosphere physics - The study of processes that take place in the upper atmosphere. Includes study of the interactions between the various atmospheric gases and cosmic radiation, such as the ozone layer.
upwelling - An oceanographic term, the rising of deeper waters to replace surface waters. Upwelling often brings waters rich in nutrients to the surface, resulting in a region where ocean productivity is high.
white-out - A weather condition in which
the horizon cannot be identified and there are no shadows. The
clouds in the sky and the white snow on the ground blend - described
as like walking along inside a ping-pong ball. White out conditions
are potentially dangerous because it is difficult to find a
point of reference and it is very easy to walk over a cliff
or fall down a crevasse in such conditions.
wind
chill - A way of describing the temperature that takes
into consideration the effect of the wind speed in the temperature
reported. Wind makes any temperature feel colder and wind chill
factor is a way of expressing how cold the wind might make the
temperature feel. First described after experiments by the American
scientist Paul Siple on baked bean cans containing water and
a thermometer left in the wind.