Sudan copper, gold, granite, gypsum, iron, kaolin, lead, manganese, mica, natural gas, nickel, petroleum, silver, tin, uranium and zinc. The amount of rainfall increases towards the south. The central and the northern part have extremely dry desert areas such as the Nubian Desert to the northeast and the Bayuda Desert to the east; in the south there are swamps and rainforest. Sudan's rainy season lasts for about three months (July to September) in the north, and up to six months (June to November) in the south. The dry regions are plagued by sandstorms, known as haboob, which can completely block out
Desert defining the boundaries of deserts and the semiarid regions that surround them on the grounds of precipitation alone is problematic. A semi-arid desert or a steppe is a version of the arid desert with much more rainfall, vegetation and higher humidity. These regions feature a semi-arid climate and are less extreme than regular deserts. Like arid deserts, temperatures can vary greatly in semi deserts. They share some characteristics of a true desert and are usually located at the edge of deserts and continental dry areas. They usually receive precipitation from 250 mm (10 in) to 500 mm (20 in) but