When wind whips up dust in a desert, the smallest particles can be lifted thousands of feet into the air and carried huge distances on high-altitude winds. One of the most striking examples is the dust storm pattern over the Sahara desert in Africa, which regularly carries massive plumes of dust all the way across the Atlantic Ocean to the Caribbean, Florida, and the Amazon basin in South America.
About 27 million tons of Sahara dust make this trip every year. You can see it clearly from satellite photos: a vast tan-brown cloud streaming across the Atlantic for thousands of miles. When it arrives over the Americas, it sometimes makes sunsets unusually red and air quality temporarily worse.
But here’s the amazing part: the dust is essential to the Amazon. Soils in the rainforest are surprisingly nutrient-poor - rain leaches minerals away quickly. The Sahara dust contains phosphorus, an essential plant nutrient that’s hard to find in the Amazon. Without that annual dust delivery from across an ocean, the Amazon rainforest would probably look very different. One of the world’s biggest forests depends on one of the world’s biggest deserts.
