Scottish and French scientists using thermal imaging found that the outer layer of an Emperor penguin’s feathers is a few degrees colder than the icy Antarctic air around it, which can drop as low as minus 40 degrees Fahrenheit. This “cold coat” may help the birds endure frigid temperatures by drawing relative warmth from the air, thereby reducing heat loss from their bodies.
So how is this possible? How can a warm-blooded bird such as a penguin actually create a “cold coat” … and how does that heat transfer work?
First, let’s look at what keeps penguins warm in the first place. It’s mainly lots of fat and a seriously thick layer of feathers that’s roughly equivalent to two ski suits.
This recent — and somewhat amazing — discovery is that the well-dressed bird’s cold coat pulls the relatively warmer surrounding air toward it. Because the bird is so well-insulated, the slightly warmer air doesn’t actually reach the skin, but it probably helps reduce heat loss from the skin.
So how do these birds create a “cold coat”? Dr. Dominic McCafferty of the University of Glasgow explains, “[T]he key to this is the temperature of the sky [which] … may be more than 20 degrees colder than the surrounding air. The temperature of the plumage is … influenced most strongly by the temperature of the sky rather than the surrounding air.
“A similar phenomenon can be observed if you park your car in the open on a cold night. Usually you will only find frost … on the roof and windscreen, but the sides do not ‘view’ the sky and therefore are radiating to relatively warmer surroundings.”
And that’s how frost on cars helps explain the cold coat. So if you parked your penguin overnight in a car in Antarctica, would it be warmer?