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
Desert whitethroat differences it follows Gloger's rule of pale colour in arid regions. The throat is white, and the rest of the underparts pale greyish-white. Three subspecies are currently recognised, though some authors only accept the first two as distinct. The presumed lesser whitethroat subspecies "halimodendri" and "telengitica" might actually belong to the desert whitethroat, or alternatively might represent hybrid intergrades between, respectively, "S. m. jaxartica" and "S. m. margelanica" and the lesser whitethroat. Desert whitethroat inhabits arid lowland regions from eastern Iran and Turkmenistan eastwards to Xinjiang in central China, breeding in open dry thorn scrub. The breeding range does not