The Sudans Nile within the Sudans has no significant tributaries. The amount of rainfall increases towards the south. In the north there is the very dry Nubian Desert; in the south there are swamps and rainforest. The Sudans’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 the sun. In the northern and western semi-desert areas, people rely on the scant rainfall for basic agriculture and many are nomadic, travelling with their
Volcanic desert or little soil formation due to slow chemical weathering caused by cold climate or coarse tephra. Volcanic desert A volcanic desert is an area devoid of vegetation because of volcanic activity. Usually the term is applied to larger areas such as the Highlands of Iceland, the Rangipo Desert in New Zealand or Cordón Caulle in Chile. Occasionally the term is used for relatively small regions such as the Kaʻū Desert on the island of Hawai'i. Volcanic deserts may have enough precipitation to sustain vegetation, but due to repeated covering of tephra and acid rain after eruptions and high percolation and