Giant Chinese dustball circles the Earth

A giant Chinese dustball weighing hundreds of thousands of tons circled the world at high altitude in under two weeks, scientists have shown.

By Malcolm Moore in Shanghai Published: 11:48AM BST 21 Jul 2009
A group of Chinese and Japanese scientists claimed that the dustball, which weighed 800,000 tons, was kicked up during a storm in 2007 in the Taklamakan desert.
The desert, which is roughly the size of France, lies in China's far-Western Xinjiang province, and is fringed by mountains on three sides, including the Pamir mountains on the border with Afghanistan and the Karakoram range, an extension of the Himalayas.

The dust ball was formed when a wind storm ripped across the desert, kicking up the dust, and trapping it against the mountains of the Tibetan plateau.
The scientists said the dust was forced higher and higher into the air, until it reached an altitude of around 16,250ft. A warm convection flow then lofted it further to between 26,000 ft and 32,500 ft, well above cloud level.
The dust was then trapped in the polar jetstream, a fast-flowing air current that lies just under the stratosphere, and began its "journey around the world" according to the Nature Geoscience journal.
The team of scientists tracked the progress of the cloud using tools aboard the Nasa observation satellite Calypso. After 13 days, the plume of dust passed back over the Taklamakan desert, having completed a full circuit of the globe. The scientists noted that even after such a long journey, the dust remained "tightly confined in latitude".
It only fell back down to earth after crossing half the globe again when the cloud encountered a ridge of low pressure and fell into the Pacific ocean. Some of the dust managed to reach North America and then fall into the Atlantic.
"The Taklamakan desert is a major source of dust transported and deposited around the globe," the scientists noted, adding that dust from the desert has turned up in ice cores in Greenland and in the French Alps. They also suggested that micro-nutrients from the dust could have a beneficial effect on the oceans, helping to feed plankton.