Sahara dust forecast
The Sahara is the largest source of mineral dust in the world, and the globe here is centred on it. Dust is lifted when strong winds blow over dry, loose ground, especially in the Bodele Depression in Chad and across Mauritania, Mali and Algeria.
On the map, look for a pale-to-dense tongue that leaves the African coast between about 10 and 25 degrees north. This is the Saharan Air Layer, a mass of hot, dry, dusty air that rides above the cooler air near the sea surface and moves west across the tropical Atlantic.
Plumes can reach the Caribbean, the Gulf of Mexico and northern South America in about five to seven days. Along the way they haze the sky, produce red sunsets and lower air quality. Over the Amazon, the dust brings phosphorus that fertilises the forest.
Another route runs north, when southerly winds push dust over the Mediterranean towards Spain, Italy and further into Europe. Switch on Wind to see which flow carries the dust. The values are in micrograms per cubic metre, and the forecast shows 48 hours in 3-hour steps.