I
ice age (glacial period) - Periods in the
Earth's history when the climate was colder and glaciers expanded to cover
large areas of the Earth's surface. Ice ages have come and gone many times and
will probably continue to do so.
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.
K
katabatic winds - Wind that results from
dense, cold air flowing down a slope by gravity. Over Antarctica, air cools
over the high plateau region and flows towards the coast, by the time it gets
to the coast it can have reached extreme speeds and blow continuously for
weeks.
L
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.
M
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".
N
nekton - Free-swimming aquatic animals that
move under their own power and can move independently of ocean currents.
Whales and 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 may have 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.
O
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.
P
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.
R
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
S
Sastrugi - wind blown snow
picture courtesy NOAA
salinity - The amount of dissolved salts
contained in sea water. The average salinity of sea water is 35 parts per
thousand, but can vary with location.
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.
T
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.
U
ultraviolet radiation (UV) - A part of the
electromagnetic spectrum that has shorter wavelengths than visible light.
Ultraviolet radiation has more energy than visible light and can damage tissue
(like human skin). Much of the ultraviolet radiation from the sun is absorbed
within the ozone layer before it reaches the Earth's surface.
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.
W
West Wind Drift (Antarctic Circumpolar Current)
- A Southern Ocean surface current flowing east and driven by westerly winds.
The West Wind Drift carries a large volume of water and it is a strong current
because no continents are in the way of the flow path.
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.
Z
zooplankton - Animal plankton. Microscopic
free-swimming or suspended marine or freshwater animals 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 column although
may be able to move small distances. Many marine animals spend part of their
lives as zooplankton, often as a juvenile life stage. One of the most
important components of the Antarctic zooplankton is krill.
|
