The Gobi desert, one of the world's great deserts, covers much of the southern part of Mongolia. Unlike the Sahara there are few sand dunes in the Gobi; rather you'll find large barren expenses of gravel plains and rocky outcrops. The climate here is extreme. Temperatures reach +40° C in summer, and -40 in winter. Precipitation averages less than 100 mm per year, while some areas only get rain once every two or three years. Strong winds up to 140 km/h at spring and fall time. Great Gobi National Park is one of the largest World Biospheres, with an area larger than Switzerland. It contains the last remaining wild Bacterian (two-humped) camels, wild ass, gazelle and a small population of Gobi bears, the only desert-inhabiting bear.