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Wednesday, June 4 2008

Penguins

By Graeme on Wednesday, June 4 2008, 15:28

Penguins are a group of aquatic, flightless birds living almost exclusively in the southern hemisphere. The number of penguin species is debated. Depending on which authority is followed, penguin biodiversity varies between 17 and 20 living species, all in the subfamily Spheniscinae.

The largest living species is the Emperor Penguin : adults average about 1.1 m tall and weigh 35 kg or more. The smallest penguin species is the Little Blue Penguin (also known as the Fairy Penguin), which stands around 40 cm tall and weighs 1 kg.

King Penguins
pinguins.jpg

Emperor penguins
emperor-penguins.jpg

Little Blue penguin
little-blue-penguin.jpg

King penguins and a seal
king-penguins-and-seal.jpg

Sources and images : Alexander Hafemann, Wikipedia

Wednesday, April 11 2007

Northern Lights

By Graeme on Wednesday, April 11 2007, 11:21

The aurora (plural aurorae/auroras) is a bright glow observed in the night sky, usually in the polar zone. For this reason some scientists call it a "polar aurora" (or "aurora polaris"). In northern latitudes, it is known as the aurora borealis, which is named after the Roman goddess of the dawn, Aurora, and the Greek name for north wind, Boreas. Especially in Europe, it often appears as a reddish glow on the northern horizon, as if the sun were rising from an unusual direction. The aurora borealis is also called the northern lights since it is only visible in the North sky from the Northern Hemisphere. The aurora borealis most often occurs from September to October and from March to April. Its southern counterpart, aurora australis, has similar properties. Australis is the Latin word for "of the South".

Sources : Wikipedia, Aurores Boréales

Thursday, March 1 2007

Antarctic Icebergs

By Graeme on Thursday, March 1 2007, 06:54

An iceberg is a large piece of freshwater ice that has broken off from a snow-formed glacier or ice shelf and is floating in open water.

Since the density of pure water ice is ca. 920 kg/m3, and that of sea water ca. 1025 kg/m3, typically, only one ninth of the volume of an iceberg is above water. The shape of the remainder under the water can be difficult to surmise from looking at what is visible above the surface. This has led to the expression "tip of the iceberg", generally applied to a problem or difficulty, meaning that the visible trouble is only a small manifestation of a larger problem.

The word iceberg is a partial loan translation from Dutch ijsberg, literally meaning mountain of ice, cognate to Danish Isbjerg, Swedish Isberg, Low Saxon Iesbarg and German Eisberg.

Source : Wikipedia, image © Alfred-Wegener-Institut

Friday, October 6 2006

Polar Bear

By Graeme on Friday, October 6 2006, 03:53


Polar bear


Polar bear cubs

The polar bear (Ursus maritimus), also known as the white bear, northern bear, or sea bear, is a large bear native to the Arctic. It is well-adapted to its habitat : its thick blubber and fur insulate it against the cold, its white coloured fur camouflages it from its prey. The polar bear hunts well on land, on the sea ice, as well as in the water.

The polar bear is a circumpolar species found in and around the Arctic Ocean whose southern range limits are determined by pack ice (their southernmost point is James Bay in Canada). While their numbers thin north of 88 degrees, there is evidence of polar bears all the way across the Arctic. Population estimates are generally just over 20 000.

Their main population centers are :

  • Wrangel Island and western Alaska
  • Northern Alaska
  • Canadian Arctic archipelago
  • Greenland
  • Svalbard-Franz Josef land
  • North-central Siberia

Their range is limited by the availability of sea ice that they use as a platform to hunt seals, the mainstay of their diet. The destruction of its habitat on the Arctic ice, which has been attributed to global warming, threatens the bear's survival as a species; it may become extinct within the century. Signs of this have already been observed at the southern edges of its range.

Source : Wikipedia