Is the Sahara the largest desert in the world?

The Sahara Desert is the largest desert in the world, covering almost all of northern Africa. It is about 4,800 kilometers (3,000 miles) long from east to west and between 1,300 and 1,900 kilometers (800 and 1,200 miles) from north to south, with a total area of ​​about 8,600,000 square kilometers (3,320,000 square miles). The Sahara Desert borders the Atlantic Ocean to the west, the Atlas Mountains and the Mediterranean Sea to the north, the Red Sea to the east, and the Sahel, a semi-desert steppe transition zone, to the south. The Sahara Desert is the largest desert in the world outside of Antarctica. It is located in northern Africa. It has extremely harsh climate conditions and is one of the most unsuitable places on earth for biological growth. The Arabic word Sahara means "great desert". It is located south of the Atlas Mountains and the Mediterranean Sea (about 35° north latitude) and north of about 14° north latitude (250 mm isohyet), stretching from the Atlantic coast in the west to the Red Sea coast in the east. It traverses the northern part of the African continent, with a length of 5,600 kilometers from east to west and a width of about 1,600 kilometers from north to south, with a total area of ​​approximately 9,065,000 square kilometers, accounting for approximately 32% of the total area of ​​Africa. The entire continental United States can be packed into it. The name "Sahara" comes from Arabic and was introduced from the language of the local nomadic Tuareg people, which means "desert" in their language. This desert was formed approximately 2.5 million years ago. The Sahara Desert starts from the Atlantic coast in the west, is bounded by the Atlas Mountains and the Mediterranean Sea in the north, reaches the Red Sea in the east, and reaches Sudan and the Niger River Valley in the south. The Sahara Desert is divided into several parts: Western Sahara; central plateau mountains (including the Ahagar Plateau in Algeria, the Air Plateau in Niger and the Tibesti Plateau in Chad; the eastern part is the most desolate area, the Tenere Desert and the Libyan Desert. The highest point of the Sahara Desert is Mount Kusi, located in the Tibet Sahara Desert, with an altitude of 3415 meters. The Sahara Desert divides the African continent into two parts, North Africa and Southern Black Africa. The climate and culture of these two parts. It is completely different. The southern boundary of the Sahara Desert is a semi-arid savanna, which is called "Sahel" in Arabic. Further south is southern Africa, which has abundant rainfall and lush plants. It is called "Sudan" in Arabic, which means Black Africa. . [Edit this paragraph] Natural features (1) Physical geography. The main terrain features of the Sahara Desert include: shallow and seasonally flooded basins and large oasis depressions, rocky highlands, steep mountains, and sandy beaches, dunes and sand seas. The highest point is 3,415 meters (11,204 feet) on the top of the Koussi Mountains in the Tibesti Mountains in Chad; the lowest point is 133 meters (436 feet) below sea level in the Qattara Depression in Egypt. (Qattara Depression). The quicksand Sahara Desert near El-Jedida in Egypt emerged as a climatic desert about 5 million years ago, that is, in the early Pliocene (5.3 million to 3.4 million years ago). Since then, it has been experiencing changes in dry and wet conditions. (2) Water systems. Several rivers originate from outside the Sahara Desert, providing surface water and groundwater in the desert, and absorbing water released by its water system network. The main tributaries of the Sahara Desert gather together, and the rivers flow northward along the eastern edge of the desert into the Mediterranean; several rivers flow into Lake Chad in the south of the Sahara Desert, and a considerable amount of water continues to flow northeast to refill the area's reservoirs. Water layer; the Niger River rises in the Fouta Djallon region of Guinea and flows through the southwestern Sahara Desert before flowing south into the sea. Streams and stems flowing from the Atlas Mountains and the coastal highlands of Libya, Tunisia, Algeria, and Morocco. Additional water is provided by river beds (seasonal streams). Particularly noteworthy is the comprehensive network of wadi beds, lakes, and ponds associated with the Tibetis Mountains, as well as the Tassili-n-Aye. Ajjer) and similar networks in the Ahagal Mountains, such as the Tamanrasset River. The sand dunes of the Sahara Desert store a considerable amount of rainwater, and there are seeps and springs in the desert. (3) Soil. The soil of the Sahara is low in organic matter and is often devoid of biological activity, although soils in the depressions are often salty. The soil on the edge of the desert has a higher concentration of organic matter. (4) Saharan climate. The desert climate is controlled by the north-south transition of the trade wind belt. It often has many extremes. It has the highest evaporation rate in the world and has the largest area of ​​​​no rainfall for several years. Temperatures can reach frost and freezing levels at high altitudes. , and the hottest weather in the world can be found at lower altitudes. The Sahara Desert is dominated by two climate regimes: an arid subtropical climate in the north and an arid tropical climate in the south. The arid subtropical climate is characterized by large annual and daily temperature variations, with cold to cool winters and hot summers to the highest precipitation. The annual range of the average daily temperature is approximately 20°C (68°F). The average winter temperature is 13℃(55℉). Summers are extremely hot. The highest temperature in Al-Aziziyah, Libya, reached a record high of 58℃ (136℉). Annual precipitation is 76 mm (3 inches), although rainfall varies greatly, with most precipitation occurring between December and March. Another rainfall peak occurs in August, which is characterized by thunderstorms. Such heavy rains can cause huge flash floods into areas where rainfall does not occur.

The dry tropical climate is characterized by a strong annual temperature cycle with the position of the sun; mild, dry winters and hot, dry seasons followed by variable summer rains. The annual average daily temperature difference in the arid tropical zone of the Sahara Desert is 17.5°C (31.5°F). The average temperature in the coldest month is basically the same as that in the northern subtropics, but the daily temperature difference is not that large. Late spring and early summer are very hot, and high temperatures of 50℃ (122℉) are not uncommon. Although precipitation in the arid tropical hills is low throughout the year, the lowlands experience the highest rainfall in summer. In the north, most of this rain occurs in the form of thunderstorms. Annual rainfall averages about 125 mm (5 inches), and snow sometimes falls in the central hills. The Cold Canary Current on the western edge of the desert lowers the temperature, thereby reducing convective rain, but the humidity increases and fog sometimes occurs. Winter in the southern Sahara Desert is the period of the harmatan, a dry northeasterly wind that carries sand and other small dust particles. (5)Plants. Vegetation in the Sahara Desert is sparse overall, with patches of grass, shrubs and trees scattered around the highlands, oasis depressions and dry river beds. Halophytes (salt-tolerant plants) are found in salty depressions. In the water-scarce plains and plateaus of the Sahara Desert there are certain grasses, herbs, small shrubs and trees that are heat and drought tolerant. Among the important remnant woody plants in the Sahara desert highlands are olive, cypress, and maraschino. Other woody plants found in the highlands and deserts include Acacia and Artemisia plants, Egyptian ginger palm, oleander, date palm and thyme. The west coast has halophytes such as Tamarix senegalensis. Grasses are widely distributed in the Sahara Desert and include the following species: Aristida, Eragrostis and Panicum. Along the Atlantic coast are Aeluropus littoralis and other halophytes. Various combinations of ephemeral plants form important seasonal grasslands, which are called ephemeral vegetation areas. (6)Animals. Relict tropical fauna in the northern Sahara include tropical catfish and cichlids, both found in Biskra, Algeria, and isolated oases in the Sahara; cobras and small crocodiles may still exist in the remote Tibesti Mountains in the river basin. The mammal species of the Sahara Desert include gerbils, jerboas, Cape hares and desert hedgehogs; Berber sheep and sickle-horned eland, dogas antelope, and dama deer and Nubian wild ass; Anubis baboon, spotted hyena, common jackal and sand fox; Libyan white-necked stoat and slender mongoose. There are more than 300 species of birds in the Sahara Desert, including non-migratory birds and migratory birds. The coastal strip and interior waterways attract many species of waterfowl and shorebirds. Birds of the interior include ostriches, various larvae, hawks, guinea fowl and Nubian bustards, desert eagle owls, barn owls, sand larks and gray rock swallows, as well as brown-necked and fan-tailed ravens. Frogs, toads and crocodiles live in the lakes and ponds of the Sahara Desert. Lizards, ducks, skinks and cobras hang out among the rocks and sand pits. Lakes and pools in the Sahara Desert contain algae, saltwater shrimp and other crustaceans. Snails living in deserts are an important food source for birds and animals. Desert snails survive through aestivation, where they remain inactive for several years before rainfall awakens them.