ABSTRACT
The Sahara is underlain by the crystalline Basement Complex which in places outcrops at the surface. It comprises a broad platform of Archaean granites and gneisses, once folded and then denuded to peneplain form. The climate of the desert is characterised by aridity, a considerable temperature range (both seasonal and diurnal), a dry atmosphere, clear skies and a maximum amount of sunshine throughout the year. The weather is remarkably stable. Rainfall is irregular and usually in the form of short and often violent storms. In some parts of the desert (e.g. the Libyan desert) years may pass between such storms. The Sahara is one of the hottest parts of the earth’s surface. The clear skies favour unbroken sunshine and the world’s highest summer temperatures have been recorded here. Saharan vegetation is related to the character of the surface rock and the presence of surface or subsoil water.
