Deserts are available almost throughout the world, with the largest being the Sahara Desert in Africa. Because hot air rises, cooler air enters to replace it in the form of wind, which can be extreme, scorching and heavily dust-laden in the Sahara Desert. Coastal ergs on the shores of lakes and oceans also do exist, and can be found in places like Oregon, Michigan, and Indiana. Polar deserts (also seen as "cold deserts") have similar features, except the main form of precipitation is snow rather than rain. For example, the Sahara desert, near the Mediterranean. The southwestern coasts of Africa and South America are swept by cold currents upwelling from the ocean floor. Deserts that form near bodies of water are usually caused by winds. Interior Deserts Deserts are formed when rain clouds run into wind or mountains and drop rain in one area, leaving the land further away dry. It is not only deserts that form dunes; the high supply of sand can form ergs anywhere, even as far north as 60° in Saskatchewan at the Athabasca Sand Dunes Provincial Park. Camels can go for weeks without water, and their nostrils and eyelashes can form a barrier against sand. Rainshadow also produce Deserts. Death Valley, the lowest and driest place in North America, is in the rain shadow of the Sierra Nevada mountains. One way is when rains clouds are carried by winds into the high mountains. In the Atacama, measurable rainfall--1 millimeter or more of rain--may occur as infrequently as once every 5-20 years. Deserts form in many ways. Crescent-shaped dunes are common in coastal deserts such as the Namib, Africa, with prevailing onshore winds. Condensation takes place later, and rain drops down on that area of the mountain, rendering the other side without rain. Over time, several factors apart from climate change have jumped in to form the deserts as we see them today. Mountains for instance, along with a number of other complex factors such as air pressure, cold air, and precipitation, contribute majorly to the formation of deserts. Any moisture in the air will fall as air passes high mountain ranges, so land beyond the mountains receives little or no rain. No clouds means no rain producing, therefore Deserts form. Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube. Death Valley, in the U.S. states of California and Nevada, is a rain shadow desert. In fact, many food deserts are also “wage deserts,” in which the work available doesn’t provide basic necessities for at least 80% of the primary jobholders. Antarctica is the world's largest cold desert (composed of about 98% thick continental ice sheet and 2% barren rock). The descending air warms up, making it difficult for clouds to form. A coastal desert, the Atacama of South America, is the Earth's driest desert. Several examples of deserts formed by mountain ranges exist in the world, such as the Gobi Desert north of the Himalayas or the deserts of Nevada east of the Sierra Nevada Mountains. How Deserts are Formed.