This article was taken from the June 2015 issue of WIRED magazine. Be the first to read WIRED's articles in print before they're posted online, and get your hands on loads of additional content by subscribing online.
This is a visualisation of dust travelling across the world through the upper atmosphere. Each year, 180 million tonnes of Saharan dust are shifted by strong winds and, according to a study published in Geophysical Research Letters, 28 million tonnes of it are swept across the Atlantic to the Amazon. And it's filled with natural fertiliser: phosphorus. "We estimate that 22,000 tonnes of phosphorus is deposited in the Amazon each year," says Hongbin Yu, an atmospheric scientist working at Nasa's Goddard Space Flight Center, and lead author of the study. "That's the same amount washed out of the soil through flooding and rainfall."
The week-long journey of the dust is tracked by Nasa's Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite. The lidar technology sends light into the atmosphere and measures how long it takes to be reflected back. "Based on the time difference between when you emitted the light and the return signal, you can estimate how much material is in the atmosphere," explains Yu.
Some of the dust travels even further. "Part of the Saharan dust will reach the west coast of the US," says Yu. This causes more rain and snowfall there by acting as condensation nuclei -- good news for the drought-prone western states, where water is at a premium. "Dust isn't always bad," says Yu.
This article was originally published by WIRED UK
