In arid regions around the world, dust and sand storms are common.
They typically whip up along large gust fronts and swirl into storm systems, wreaking havoc with air traffic, as well as with life on the ground.
Just such a storm roared across the Arabian Peninsula in early March 2009, blanketing cities across the region, including Riyadh, Saudi Arabia, pictured here.
Riyadh Dust Storm
March 3, 2009
Residents in Riyadh braved near-zero visibility as a massive dust storm swept through the region.
March 3, 2009
The effects of dust storms extend far beyond traffic headaches. As dust storms blow out to sea, they can be transported thousands of miles.
Sahara Desert Plume
Dust blowing off the Sahara Desert each winter makes its way across the Atlantic Ocean.
Rich in iron, the dust is a vital nutrient that helps sustain marine ecosystems, but can also trigger toxic blooms of algae, like red tides, that kill fish and damage corals.
It takes less than two weeks for a dust plume to lift off in Africa, cross the Atlantic, and settle in the Caribbean, the United States, or South America. Saharan dust also finds its way into the Mediterranean, including Italy and Greece, and sometimes as far north as England.
Human activity constantly ramps up the amount of dusty material in the atmosphere.
Hong Kong is always caught smack in the middle of a massive pollution phenomenon scientists call the Giant Brown Cloud or the Asian Brown Cloud.
The health consequences of atmospheric brown clouds are severe. A 2002 study estimated that 1.6 million people die prematurely as a result of inhaling air pollution. Most diseases related to air pollution attack the lungs, including asthma, respiratory infection, and lung cancers.
Haze from automobile combustion and biomass burning, like this huge smoke plume over the island Borneo in Southeast Asia (1997), can block out the sun for a short while, causing local cooling.
But aerosols in the atmosphere rival carbon dioxide as an agent of warming, exacerbating humanity's effect on climate.
Massive development throughout Asia is mostly to blame for the smoggy blanket that now engulfs much of the region.
This monstrous cloud that formed in 2004 is actually pollution crowded up against the Himalaya Mountains in India and Nepal, and is spilling southeast into Bangladesh.
China Dust Storm
Residents of developed countries are not immune to the ill effects of the increasingly dust and smog-choked Asian skies.
Large upticks in water consumption, intensive farming practices and deforestation in China have led to more frequent dust storms, like this one in 2001 that swept aerosol particles into the Great Lakes region of the US, and even left a sprinkling in the Alps mountains in Europe.
by Discovery News' Michael O'Reilly