Thursday, January 10, 2008

Head in the Clouds

Have you ever spent a lazy afternoon watching the clouds go by? University of Utah meteorologist Tim Garrett spends lots of time observing clouds, but for him it’s not a relaxing pastime; it’s his job. “I want to understand how clouds work,” he says. “They appear and disappear, they’re constantly evolving. Why?” Garrett hopes to uncover some simple principles that guide the behavior of these “ephemeral beasts.”

Garrett’s interest in the nature of clouds isn’t purely academic. Understanding the details of how clouds work is important to scientists trying to predict the future effects of climate change. As the Earth warms, clouds might act like a blanket, trapping heat in the atmosphere just like greenhouse gases do, and making the problem worse.

Or instead, clouds might act like a shield, reflecting sunlight back into space and slowing the effects of global warming. It all depends on how the clouds themselves react to a changing climate: different kinds of clouds have different effects on the atmosphere. Nobody knows which ones will dominate. But a better understanding of how clouds work might help predict what will happen in the future.

Garrett's work unraveling the mysteries of clouds takes a lot of different forms. He's done research on how pollution affects snowfall and sea-ice melting in the Arctic, on the size of ice crystals in cirrus clouds, and on the motions in clouds. He relies on data collected by satellites, airplanes, and ground-based weather stations to draw his conclusions, but he swears that one of the best sources of information is something everyone has access to: the sky outside. "I just look at the sky and there's huge amounts of information there," he says. "I look at a cloud and think, 'How much light would this reflect? What can I see through the cloud? What does the sun look like?' The most sophisticated instrument ever developed is the human eye. If you're patient, and keep your eye on the sky, you can learn a lot."

What can you notice about clouds? Check out these videos of clouds evolving, or go look at the sky outside!

Watch timelapse videos of clouds evolving!