The word Sahara comes from Arabic word which means ‘mouse-colored’.  The Arabs have considered the Sahara to be a vast stretch of barren land.  Islamic culture began to associate Sahara with death and cemetery.  Individuals who inhabit the Sahara also associate the desert with death (Gerster, Georg, Sahara Desert of Destiny).  The Sahara desert is the largest desert in the World, having an area of 3,500,000 square miles (about the size of the US).  Many nations of Northern Africa such as Algeria, Morocco, Tunisia, Libya, Egypt, Mauritania, Mali, Senegal, Niger, Chad and Sudan contain the Sahara Desert.  Several geographic locations such the Atlantic Ocean, the Atlas Mountains, the Mediterranean Sea, the Red sea and the Sahel Steppe surround the Sahara Desert.  The desert runs 3000 miles from east to west, and 1200 miles from north to south.  The Sahara Desert may be divided into 3 portions, namely, the Libyan Desert (which runs from Eastern Libya to the Nile Valley), the Arabian Desert (which runs between the Nile Valley and the Red Sea) and the Nubian Desert (present in the Northeast of Sudan).  The various rocks landscape types present in the Sahara include sand dunes, Hamada (denuded rocks), gravel plains and flat areas.  Rocks occupy about 70% of the entire desert, and hence it is considered to be a stone desert.  Only 15% are occupied by sand dunes. The remaining 15% are occupied by mountains, oasis, and transition zones.  Many people have suggested that the Sahara may be expanding into the surrounding regions.  (Columbia University Encyclopedia).  The Sahara occupies about 10% are of the entire African continent.  Many organisms (including plants and animals) have adapted themselves to suit the Sahara climate.  Only recently (last few thousands of years) has the rainfall increased in the Sahara slightly.  Recently, the fossils of a great mammal (considered to be the Supercroc) were found in the Sahara Desert (WWF).

The vegetation in the Sahara is sparse and very little perennial forms exist.  In the Sand dunes, vegetation is completely absent.  The plants in the Sahara Desert are Xerophytes, Ephemeral (they survive only during the favorable conditions that exist after the rains) and halophytes (which may be present only in areas receiving some rainfall).  After a rain, about 20% of the sand dunes and 50% of the gravel plains seem to be covered with vegetation.  Plants have to adapt to the extreme high temperatures and drought situation in order to survive in the Sahara.  Some of the plants in the Sahara belonging to the genus Euphoria tend to sustain during the entire year.  These plants have developed a special adaptation by which they are able to absorb the rain water and store it for use later.  Often the only relief for the plants is to grow underground.  The vegetation in the Sahara is slightly greater in the northern and southern ends as these regions receive a slightly greater rainfall compared to other regions.  In the Western Sahara, a greater variety of plants are found compared to the Eastern Sahara, due to a reduced rainfall in the Eastern regions.  Less than 500 species of plant varieties are found in the entire Sahara region (WWF).

The animals present in the Sahara have adapted to the arid conditions of the Sahara.  More than 70 species of animals and 90 species of birds are present in the Sahara.  Among the arthropods, ants are present in significantly large numbers.  Only one species of bird Oenanthe monacha, and one species of snakes Leptotyphlops, are exclusive to the Sahara region.  Many species of antelopes are present in the desert (WWF).

The climate of the Sahara does not support life.  Strong winds blow from the northeastern region, from the high-pressure regions to the low-pressure region.  Across the desert, these winds become dry and warm.  Most of the Sahara records a temperature of about 12.7 cm annually.  Some transition areas may have about 25 cm of rainfall annually.  Sometimes, rainfall occurs after several years, and in such cases may be very heavy.  The mean annual temperature in the Sahara is above 30ºC, and it the hot season it easily gets above 50ºC.  During the night times, the heat is lost rapidly, and during winter months, the temperature can even fall below 0ºC (Columbia University Encyclopedia).  The oasis present in the Sahara has been places of special interest.  People in the Sahara have used the one-humped camel as a mean of transport.  The camel is considered to be vast and can bear extreme desert conditions including desert storms.  The Sahara has been a land were many civilizations, races, people, tribes, etc have lived (Gerster, Georg, Sahara Desert of Destiny).

Thousands of years ago the Sahara was green and man hunted animals.  The countryside consisted of giraffes, grasslands, buffalos and several lakes.  More than 12, 000 years age, several climatic alterations in North Africa helped to change the environment of the Sahara.  Several rock caves paintings in Tassili-no Ajjer, Algeria demonstrate the life that existed in the Sahara (Lhote, Henry, National Geogrtaphics).  The Painting also demonstrates other animals such as elephants, hippopotamus, crocodiles and fish.  The occupation of the people during that time was hunting; demonstrate by the weapons present in the paintings.  Arid conditions slowly began to develop in the Sahara.  Thus the lakes, grasslands and animal life also began to slowly disappear and such life is now endangered (Gerster, Georg, Sahara Desert of Destiny).

References:

Answers.Com. “Sahara.” Encyclopedia. 2006. Answers.Com. 10 Jan. 2007 http://www.answers.com/topic/sahara