Wednesday, January 10, 2007

Polar Bear

It's snowing up here in Waterloo. I wish I was a polar bear! They aren't only cute but quite interesting guys.

Since they are hard to see in snow, researchers thought some while ago, it would be a good idea to search for them in the infrared. To their surprise, they didn't see much, see the picture to the left. There's eyes, nose, ears, but where is the rest?

Well, this paper

"Radiative Properties of Polar Bear Hair,"
By Preciado, Rubinsky, Otten, Nelson, Martin, and Greif,
BED-Vol. 53, 2002 Advances in Bioengineering, ASME 2002.

summarizes the results of an investigation which shows that polar bear hair has the same radiative properties as snow.
Amazing animals, eh? Though the military was originally very excited about the bears for creating infrared camouflage in cold climates, they quickly lost interest when they discovered that the polar bears could easily be seen in the ultraviolet.

Some more info at this website.



  1. The polar bear in infrared is cute :-)
    I first thought it is some funny-coloured hippo...
    It amazes me again and again where you dig out all these nice little stories!

    Don't freeze too much,


  2. From the author of Winnie-the-Pooh, just change brown to white :)

    If I were a bear,
    And a big bear too,
    I shouldn't much care
    If it froze or snew;
    I shouldn't much mind
    If it snowed or friz--
    I'd be all fur-lined
    With a coat like his!

    For i'd have fur boots and a brown fur wrap,
    And brown fur knickers and a big fur cap.
    I'd have a fur muffle-ruff to cover my jaws.
    And brown fur mittens on my big brown paws.
    With a big brown furry-down up to my head,
    I'd sleep all the winter in a big fur bed.

  3. lol! Bee, not surprised the military were not interested
    Polar Bear camouflage a bit of a give away in ultraviolet
    So which wavelength sheds light on neutrinos - are they camouflaged in dark matter?

  4. I wish I was a polar bear!

    Actually what I wanted to say is that in case your wish comes true, then I wish I could see Stefan's face :)

  5. Polar bears are having problems caused by melting ice sheets:

    "The thinness of the ice covering the Arctic Ocean, approximately three metres deep, makes it far more vulnerable to longer summers than the glaciers of the Antarctic. A 40% thinning of the ice has occurred since the 1960s. Polar bears rely on the ice to hunt for seals, and its earlier break-up is giving them less time to hunt. Continued decrease in the Arctic's ice cover would also act to increase the effects of global warming in the northern hemisphere by decreasing the amount of sunlight reflected by the ice. It is also believed that the Arctic ice plays a role in the operation of the Gulf Stream, and that this could be disrupted by continued thinning."


    There was a recent TV programme here in England about polar bears which stated that they have been found swimming as far as 200 miles off the edge of the ice. They can survive for several days in freezing water, but lose body weight faster when swimming in the sea than when walking on ice, and they cannot hunt for food in the water - they are simply too big and cumbersome.


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