Deserts are all dry, arid places, but they are not always hot. Some deserts can be cold most of the year depending on their location. At night, hot air from the day dissipates and, in some areas, temperatures can drop below freezing.
Many hot deserts lie in the subtropical zones. The Sahara Desert is the World's largest desert and covers 3.5 million square miles (9 million square kilometers), making it larger than the whole Australian continent. Temperatures during the day can soar over 100° F (38° C), but drop below freezing at night. Another hot desert can be found in the Namib Desert in southern Africa. Most cold deserts are found in higher latitudes and higher elevations. They are usually found between the subtropics and polar regions. Some cold deserts include the Gobi Desert of central Asia, the Pataonian Desert of South America, and the Great Basin Desert in the southwestern United States.
Hot and cold deserts, no matter where they are located, are always dry. Arid regions are characterized by having less than 20 inches (500 millimeters) of rain annually. Although, most deserts only receive 10 inches (25 centimeters) per year.