Satellite image of a dust storm in Chad

NASA/GSFC / Jacques Descloitres, MODIS Rapid Response Team

The Bodélé depression on the eastern edge of the Sahara desert in northern Chad is the dustiest place on Earth.

The giant dust clouds, up to 700 kilometres long, that form there can affect global as well as local climate. The clouds reflect sunlight, cooling the ground below, but also play a role in determining whether storms off Africa's Atlantic coast will develop into hurricanes when they reach the Americas, on the opposite side of the ocean.

In this article in Nature, Jim Giles reports on efforts to learn how the clouds form, and what effects they have on climate.

The Bodélé was once submerged by Lake Megachad, which shrank six thousand years ago. As the water retreated it left behind the remains of microscopic animals. Over time, their remains have formed a material known as diatomite.

Enduring extreme conditions, researchers have found that the dust clouds are created when winds blow pellets of diatomite up and over sand dunes, forcing the pellets to grind against each other.

The researchers are now trying to find out more about the clouds' role in climate.