a desert in N Africa, extending from the Atlantic to the Red Sea and from the Mediterranean to central Mali, Niger, Chad, and Sudan: the largest desert in the world, occupying over a quarter of Africa; rises to over 3300 m (11 000 ft) in the central mountain system of the Ahaggar and Tibesti massifs; large reserves of iron ore, oil, and natural gas. Area: 9 100 000 sq km (3 500 000 sq miles). Average annual rainfall: less than 254 mm (10 in.). Highest recorded temperature: 58°C (136.4°F)