Dust from the Sahara just a sneeze away

04 July 2007 | 12:39 Code : 14415 Geoscience events
Droughts followed by tropical downpours followed by . . . Saharan dust storms....

  Droughts followed by tropical downpours followed by . . . Saharan dust storms.A mammoth cloud of African dust is heading in our general direction, close behind the disturbances that brought torrential rain to parts of the region.Joseph Prospero, a professor of atmospheric chemistry at the University of Miami's Rosenstiel School of Marine and Atmospheric Science, said the dusty, reddish-brown cloud hovered Wednesday over the Caribbean and Atlantic.It was likely to complete its 6,000-mile trip to Florida by Friday, the first of many wind-blown deliveries of soil that blows off the Sahara this time of year and ends up on our lawns, fields -- and cars.''This would be the first big one of the season,'' said Prospero, an expert on the phenomenon. ``It's really quite dense, really quite striking.''Fortunately, he and others said, it probably will not pose a really big threat to health, largely because much of it may pass to the south. Large concentrations of the dust can irritate those who suffer from asthma or similar conditions.''I don't think we'll get the brunt of it this time around, though we'll probably get some,'' said Robert Molleda, the National Weather Service's warnings coordinator for South Florida.In general, Saharan dust storms, which generally arrive between June and August and can shroud sunsets in a pale yellow haze, can be our friend:For reasons not completely understood, the dust storms or the meteorological conditions that accompany them tend to suppress the development of hurricanes.''They somehow work on cloud mechanisms,'' Prospero said.Moreover, they help build Florida -- literally.Top soil in much of the state includes copious amounts of reddish African dust, deposited over countless eons.''Africa is contributing to our soils here in Florida,'' Prospero said. ``What you are seeing is geology at work, very slowly.''


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