Note: Traveling Dust Animation - The dust comes every year during northern Africa's dry season, when storm activity in the Sahara Desert and Sahel generate clouds of dust. The dust originating from fine particles in the arid topsoil is transported into the atmosphere by winds and may be carried in excess of 10,000 feet high into the atmosphere by easterly trade winds. Typically, it takes one to two weeks for the dust clouds to cross the Atlantic Ocean and reach the continental United States.. This animation illustrates microbes hitching rides across the Atlantic in the highly irregular nooks and crannies found in the surfaces of dust particles and how they are transported across the Atlantic Ocean. Animator: Susan Twardy (HTSI). Writer: Deanna Kekesi (NASA/GSFC).