Airborne study reveals surprisingly large role of desert dust in forming cirrus clouds.
Every year several billion tonnes of mineral dust are lofted into the atmosphere from the world's arid regions, making dust one of the most abundant types of aerosol particles in the atmosphere. Now, scientists are learning that tiny bits of dust from the hottest and driest parts of the Earth are a surprisingly large driver in forming the delicate, wispy ice clouds known as cirrus in the cold, high-altitudes of the atmosphere.
While scientists have known that desert dust particles can seed certain clouds, the extent of that relationship has been a long-standing question. New research, based on the largest-ever airborne atmospheric sampling mission and published in Nature Geoscience, sheds light on the role of dust in the climate system.
"Dust-initiated cirrus clouds are surprisingly abundant, accounting for 34 to 71% of all cirrus clouds outside of the tropics," explained lead author Karl Froyd, a CIRES scientist at NOAA's Chemical Sciences Laboratory with the Aerosol Properties & Processes research program at the time of the study. "Perhaps even more surprising, we found that although the Sahara Desert is by far the world's largest dust emitter, the deserts in Central Asia are often more important sources for cirrus formation."
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