 The Sahara is the major source on Earth of mineral dust (60-200 million tons per year).Saharan dust can be lifted by convection over hot desert areas, and can thus reach very high altitudes; from there it can be transported worldwide by winds, covering distances of thousands of kilometers.The dust combined with the extremely hot, dry air of the Sahara Desert often forms an atmospheric layer called the Saharan Air Layer which has significant effects on tropical weather, especially as it interferes with the development of hurricanes.