The Sahara has rocky plateaus as well as sand dunes. During the summer, the temperature in the Sahara can reach over 50°C (122°F), making it one of the hottest deserts on Earth. Despite these temperatures, the Sahara is home to olive trees, antelope, jerboa, scorpions, jackals, and hyenas.
Over 25 per cent of the Sahara's surface is covered in sand sheets and dunes, with some pyramidal dunes reaching almost 150m (500ft). The highest dunes in the Sahara are found in the Isaouane-n-Tifernine desert in Algeria, with staggering heights of 420 to 465m (1,377 to 1,525 feet).
The Sahara is mainly rocky hamada (stone plateaus); ergs (sand seas – large areas covered with sand dunes) form only a minor part, contrary to common misconception, but many of the sand dunes are over 180 metres (590 ft) high.
The remote Kufrah district in southern Libya sits at the heart of the Sahara Desert. Filled with sand dunes and rugged plateaus, much of the district is extremely arid. But it wasn't always so dry. Buried beneath the shifting sand dunes is a vast fossil aquifer and remnants of now-dried rivers.
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How did the Sahara get so much sand?
From the erosion of the underlying rocks. Also, sand formation got something of a head start, as there were large scale sand reservoirs in fluviatile systems before the desertification really went haywire. Some of those fluviatile deposits got remobilised in eolian dunes once the rivers went dry.
The Sahara Desert is apparently green with vegetation—about every 21,000 years or so. But despite its rarity, this periodic “greening” of the Sahara still provides plenty of opportunities for a truly different perspective on the desert.
The Sahara Desert was once underwater, in contrast to its present-day arid environment. This dramatic difference over time is recorded in the rock and fossil record of West Africa. The region was bisected by a shallow saltwater body during a time of high global sea level.
The Richat Structure is a deeply eroded, slightly elliptical dome with a diameter of 40 kilometres (25 mi). The sedimentary rock exposed in this dome ranges in age from Late Proterozoic within the center of the dome to Ordovician sandstone around its edges.
These images depict a period approximately 6,000-11,000 years ago called the Green Sahara or North African Humid Period. There is widespread climatological evidence that during this period the Sahara supported wooded savannah ecosystems and numerous rivers and lakes in what are now Libya, Niger, Chad and Mali.
The temperature in the desert can change drastically from day to night because the air is so dry that heat escapes rapidly at night. The daytime temperature averages 38°C while in some deserts it can get down to -4°C at night.
The Sahara is the hottest desert in the world – with one of the harshest climates. The average annual temperature is 30°C, whilst the hottest temperature ever recorded was 58°C. The area receives little rainfall, in fact, half of the Sahara Desert receives less than 1 inch of rain every year.
Approximately 30% of the Western Sahara is controlled by the Polisario Front; the remaining 70% is occupied by Morocco. Morocco maintains the Berm, a 2,700 km-long (1,700 mi) wall lined with land mines that splits the territory.
The Sahara does experience rain, but usually just a few inches a year and rarely in late summer. Over two days in September, however, intense rain fell in parts of the desert in southeast Morocco, after a low pressure system pushed across northwestern Sahara.
During the African humid period, lakes, rivers, wetlands and vegetation including grass and trees covered the Sahara and Sahel, creating a "Green Sahara" with a land cover that has no modern analogues.
1. The Lut Desert. The Lut Desert, or Dasht-e Lut, a 20,000-square-mile (51,800-square-kilometer) area of eastern Iran is often the hottest place on the planet in any given year.
And while the Sahara's dunes and overall size are impressive, what lies beneath its sands is arguably this region's most astounding feature. There is the remnant of a massive lake that existed in the western Sahara around 250,000 years ago, deep beneath the sands.
Saharan dust provides marine ecosystems with important nutrients. Iron is a necessary micronutrient for photosynthesis in marine primary producers such as phytoplankton. In parts of the Atlantic, dissolved iron is thought to limit the amount of photosynthesis that phytoplankton can carry out.
The image below shows the large dust cloud that was situated just off the West coast of northern Africa, at the end of January 2024. Some of this dust is then transported across Europe and into the UK via southerly winds.
The annual range of average daily temperatures is about 75 °F (23.9 °C), increasing to a little more than 100 °F (roughly 38 °C) during the day and dropping as low as 25 °F (about –3.9 °C) at night. Winters are relatively cold in the northern regions and cool in the central Sahara, and the summers are hot.
Paleoclimate and archaeological evidence tells us that, 11,000-5,000 years ago, the Earth's slow orbital 'wobble' transformed today's Sahara desert to a land covered with vegetation and lakes.
The depth of sand in the Sahara desert varies across locations and seasons, making it difficult to provide a definitive answer. On average, the depth is estimated to be around 16 feet (5 meters). Within the Sahara desert, notable sand dunes called ergs can be found.
