Penguins: Now with more color

There's a whole gallery of these eerie, psychedelic penguins at Wired, part of Nadia Drake's article about new research based on infrared thermal imaging. Strangely, researchers found that the exterior surface of the penguins was actually colder than the surrounding air. This, despite the fact that penguins maintain a fairly stable interior body temperature that's far warmer.

The researchers involved in the study think that discrepancy might be caused by an extreme form of radiative cooling. Basically, everything emits heat in the form of radiation. You, me, the Earth, penguins — we're all constantly losing heat as it radiates away from our surfaces. During the day, we get heat back from the Sun. At night, while there is some heat coming to us from space, it's much less. And on clear, windless nights — when there isn't a cloud clover to bounce our own heat back at us — we get even colder. As Drake points out, this theory doesn't totally work for the penguins. They were photographed on a pretty windy night. But it certainly produced some great images. Here's a link to the original paper, which you can read for free.


  1. Very, very, very tangentially related: this morning I happened to read a decades-old Steve Allen joke that NBC was going to save money by becoming a black and white network, and changing their slogan to “Proud As A Penguin”.

    I can only imagine the jokes Mr. Allen would come up with if he knew that penguins are pretty colorful when viewed in a different light.

  2. This made me think of how well snow works as an insulator.  Seems counter-intuitive,  but you can actually keep your home warmer by packing snow around the outside walls during winter.  (Think of igloos, for example.)

  3. This is a good example of how sensible heat flows in the opposite direction to what we are used to during the polar night:  the air actually loses heat to the ground (and penguin feathers — notice from the picture in the article that they are about the same temperature as the ice on which they are standing), which then gets lost to space via blackbody radiation.  This down-and-out energy flow then cools the air at the surface and creates the really strong atmospheric inversions that happen over the wintertime arctic.  This is opposite to temperate/tropical daytime conditions, where the ground (and ostriches, etc.) absorb sunlight and contribute sensible heat to the air, generating convection.

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