Inside information

摘要

There's more to clouds than meets the eye. Look up on an overcast day, and you'll be presented with a sea of grey. But this blanket blotting out the Sun is merely the base of an intricate layered structure that rises vertically through the atmosphere. The composition of these layers helps to dictate what effect the clouds have on our climate. The results can be dramatic — but little is known about how these effects come about. Two satellites, scheduled for launch next month, are set to change all that. Named CloudSat and CALIPSO, these satellites will use radar and an equivalent technology based on light waves, known as lidar. They will cut through the layered structure of clouds to see how water droplets and airborne particles, or aerosols, are distributed around the globe. "This is a truly exciting time," says Graeme Stephens, a climatologist at Colorado State University and head of the CloudSat science team. "We're entering a new era of Earth observations with these missions."