By Sid Perkins
Scientists have combined simultaneous observations from satellite sensors and ground-based radar to construct a detailed, three-dimensional map of a high-altitude cirrus cloud. Such thin, wispy clouds waft above as much as 30 percent of Earth’s surface, and the new analytical technique may help researchers quantify the clouds’ precise effect on Earth’s climate.
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Cirrus clouds, which typically appear at high altitudes and are predominantly made of ice crystals, can occur at any latitude in any season, says Kuo-Nan Liou, an atmospheric scientist at the University of California, Los Angeles. The clouds cool Earth’s surface slightly by reflecting some sunlight back into space, but they also warm the lower atmosphere by trapping some of the planet’s outbound infrared radiation. The exact influence of the global fleet of cirrus clouds depends upon the average size and distribution of the clouds’ ice particles, among other factors.