From 10,000 to 5000 years ago, the Sahara Desert was wet, green, and covered with lakes! Over those thousands of years, minerals precipitated out of the water and were deposited on the lake beds. Now that it is a dry desert, high temperatures cause rapidly rising hot air currents to lift those minerals high into the atmosphere, where prevailing western winds carry the dust across the Atlantic to the Americas.
While the dust movement varies in intensity over time, it is almost always present to some degree. In the winter, dust is typically sent to South America. In the summer, it sends the clouds toward North America.
The effects of the dust on human respiratory allergies are regrettable, but plants love the minerals contained in the dust, primarily the phosphorus and iron. Saharan dust is a primary nutrient source of the Amazon rain forest, the “lungs of the world”, enabling the production of oxygen and the sequestering of carbon dioxide. For plants, and us, as we depend on them, this brown cloud does have a silver lining.
-James Gill
mary says
After the heavy thunderstorm was over here in Georgia and when the ground was finally dry I saw this off white looking powder on my lawn. I Google it and I thank you so much for your knowing. Now my kids don’t think I am crazy.
Brenda L Hutchens says
Thanks so much for this positive info on something that everyone is complaining about. It is good to know that my plants are benefiting. The summer temps keep me inside anyway, so I can avoid sun and dust, but still see my garden thrive early in the morning and late in the evening with a little water. I appreciate your post.