The direction in the sky (in the constellation Columba) away from which the Sun seems to be moving (at a speed of 19.4 km/s) relative to general field stars in the Galaxy.
A cold, dry air mass developed over the continent of Antarctica. Antarctic air is generally colder at the surface in all seasons, and at all levels in austral (Southern Hemisphere) autumn and winter,
than arctic air.
The glacial anticyclone that has been said to overlie the continent of Antarctica; analogous to the Greenland anticyclone. Until the International Geophysical Year there had been insufficient observat
ional evidence to either support or contradict this theory.
A water mass formed by deep winter convection at the coast of Antarctica, particularly in the Weddell and Ross Seas but also at other shelf locations. Being the densest water mass of the World Ocean,
AABW is found to occupy the depth range below 4000 m of all ocean basins that have a connection to the Southern Ocean at that level. At the time of formation its temperature is close to the freezing point (-1.9C), but to enter the oceans, AABW has to pass through and mix with the water of the Antarctic Circumpolar Current, which gives it its typical salinity of 34.7 psu and temperature of +0.3C. Because of this it is also known as Antarctic Circumpolar Water, particularly in the Indian and Pacific Oceans.
Latitude of 66.5 South. The northern limit of the area of the Earth that experiences 24 hours of darkness or 24 hours of day at least one day during the year.
The line of latitude 66 deg 34 min S (often taken as 66S). Along this line the sun does not set on the day of the summer solstice, about 22 December, and does not rise on the day of the winter solstic
e, about 21 June.
An eastward flowing current, also known as the West Wind Drift, that circles Antarctica and extends from the surface to the ocean floor. With a volume transport of 130 Sv (130 x 10^6 m^3/s) it is the
largest of all ocean currents. Current speed in the ACC is comparatively modest (0.1 m/s, but larger in fronts), the large transport being achieved by the current's great depth. Seventy-five percent of the transport occurs in the polar and subantarctic fronts that make up only 20% of the ACC area. Interannual variability is about 15% of the mean but can reach 40% on occasions. The ACC is influenced by bottom topography, which causes deflections from its general westward path and eddy formation, particularly at the Scotia Ridge, the Kerguelen Plateau, and the Macquarie Ridge. The eddies are instrumental for the poleward transport of heat across the current, which would otherwise block meridional heat transfer.