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The Sahara Desert,      (cover) most of North Africa, is the largest desert in the  world. From north to south the Sahara is between 800 miles       1200 miles and is at least 3000 miles from east to west. Due to the large size of the Sahara, Africa is split into two regions: that     lies above or forms part of the Sahara and the rest of Africa south  of the Sahara. On the west, the Sahara is       (border) by the Atlantic Ocean and on the  east by the Red Sea, and to the north are the Atlas Mountains and Mediterranean Sea. Over 25 percent of the Sahara's surface is covered by sand sheets and dunes.
The Sahara's climate consists     basically two sub-climates ,a dry subtropical  climate in the north and a dry tropical climate in the south. The dry tropical climate is      (general) characterized by mild, dry winters, a hot dry season just before the rainy  season, and an annual temperature cycle. The dry subtropical climate,       ,is  characterized by        (annual) high temperature ranges, cold winters, hot summers and two rainy seasons. There is a narrow strip in the western portion of the Sahara,        the  coast, which generally has cool temperatures        (compare) to the rest of the Sahara  because of the influence of the cold Canary Current.