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Dust in the Wind
Mon Aug 09, 2004
Listen in RealAudio 
Seventy years have passed since the worst Dust Bowl years in North America produced black blizzards across the continent. But dust in the air is still a never-ending nemesis. Hi, I’m Bryan Yeaton, and this is The Weather Notebook.
Wind-blown dust visits us on many different size scales. The largest are immense dust storms that blow out of China or the Sahara Desert crossing the oceans to the Americas.
Smaller scale dust events occur in the Western and Plains States each year, though none recently have reached the magnitude of the 1930s Dust Bowl. Most arise from strong localized winds associated with the passage of weather fronts, or by strong thunderstorms.
The greatest immediate hazard of wind-blown dust is a reduction in visibility, particularly when the dust blows across highways. Each year, dozens are killed or seriously injured in blown-dust related traffic mishaps.
The National Weather Service issues blowing-dust advisories and warnings when conditions warrant. An advisory means windblown dust has reduced visibility to under a quarter mile. If visibility drops further, a blowing dust warning is issued.
When blowing dust covers a large area and horizontal visibility is less than 5/8 mile, it becomes a dust storm, which may last from several hours to a few days. American observational practices define a severe dust storm when visibility drops less than 5/16 mile.
Dust from industry and other human activities are major air quality concerns across North America. For example, road traffic, including particles generated from tire and break wear and road wear, produces millions of tons of dust annually over our large cities.
Dust storms can have a devastating effect on crops and livestock, natural biota, commerce, and the health and well-being of the residents in the effected area.
Thanks to our contributing writer, meteorologist Keith Heidorn. The Weather Notebook is funded by Subaru and the National Science Foundation.
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