Sahara Desert

The other side of the world could be closer than you think. Little pieces of Earth, particles of dust, can travel halfway around the globe and alter air quality, affecting animals, plants and weather. Summer storms from the planet's deserts kick up literally millions of tons of dust, and winds send it flying to far-flung destinations where it clogs our lungs, changes soil chemistry, deposits minerals in bodies of water and reflects the Sun's rays back into space.

In July 2000 alone, nearly 8 million tons of dust from Africa's Sahara desert reached as far west as Puerto Rico. "If you figure that a pickup truck weighs 1 metric ton, that dust weighed as much as 8 million pickups," says NASA aerosol researcher Dr. Peter Colarco. Colarco works to create computer simulations that forecast the movement of dust given current weather conditions. NASA and its partner agencies want to know what drives the movement of this dust and how exactly the dust changes our environment, not only so scientists can better understand the health of our planet, but also so they can predict where dust will imminently affect people.

Take the case of Africa. Winds blow twenty percent of dust from a Saharan storm out over the Atlantic Ocean, and twenty percent of that, or four percent of a single storm's dust, reaches all the way to the west side of the Atlantic. The remainder settles out into the ocean or washes out of the air with rainfall. Scientists think that the July 2000 measurements, made in Puerto Rico, equaled about one-fifth of the total year's dust deposits. If these estimates hold true over the long term, then the entire state of Florida receives about three feet of dust every million years.