Knowing more about clouds in the Arctic may help to explain why climate change is warming the region twice as fast as the rest of the world, making life hard for polar bears. From ten years of observations by instruments in the north of Greenland, Sven-Erik Gryning of the Technical University of Denmark and colleagues have found that Arctic clouds do not behave as predicted by simulations, especially in spring when there are fewer clouds than expected, which affects the way that heat moves through the atmosphere.
When a cloud passes overhead on a sunny summer day, you feel colder, because the cloud blocks the sunlight from reaching you at the surface. But at night clouds act like a blanket, trapping heat released by the ground and making cloudy nights feel warmer. So understanding how clouds behave in the Arctic is important for understanding climate change there.