We know our amazing
planet is home to a stunning array of different climates and geographies. From
the highest mountains to the lowest valleys, from the coldest places on earth
to the warmest, Mother Nature has covered just about every extreme we can think
of. Deserts are one of those extremes—typically very dry areas, often with an
unforgiving climate and temperatures wild enough to break thermometers.
The boundaries of the Great Basin Desert are actually
somewhat fuzzy, but most people agree on one thing: it’s the largest desert in
North America, even if we aren’t quite sure just how big it is. Like the
deserts of South America, the Great Basin Desert was created by the rain shadow
of the Rocky Mountains. Encompassing most of Nevada and stretching into
California, Idaho and Utah, the desert is known for its extreme temperatures:
daytime temperatures exceed 32°C (90°F) and then drop as low as 4°C (40°F) at
night. Summers are hot and dry, while winters are cold and snowy thanks to
frigid alpine ridges. Although temperatures can be more extreme in the nearby
Mojave and Sonoran deserts, the Great Basin Desert owes its more “moderate”
climate to its elevation: there are up to 33 peaks that exceed 3,000 m (9,800
ft)!
8. Great Victoria Desert
Mention of Australia tends to evoke images of the Outback, a
desert area with little life and harsh climates. While much of the continent is
covered by arid areas, it’s not just one big desert. The Great Victoria Desert,
located in south and western Australia, is the largest of all Australian
deserts, covering approximately 350,000 km (135,000 miles). Average rainfall is
irregular, ranging between 200 and 250 mm (8 and 10 inches). The temperature is
also variable: daily highs can reach 40°C (104°F) in the summer, and lows of
about 18°C (64°F) in the winter. Thunderstorms happen with frequency; on
average, 15 to 20 thunderstorms will take place in the desert annually. The
Great Victoria Desert is close to several other deserts: the Little Sandy and
Gibson deserts lie to the north, while the Triari and Sturt Stony deserts are
to the east.
7. Sahara Desert
If someone says desert, you likely think of miles of rolling
sand dunes, winds gusting along across them. You probably think of a sweltering
sun and maybe a caravan traveling by camel through the area. Welcome to the
Sahara Desert, the world’s largest hot desert—and the prototype for all other
“deserts.” The Sahara is such the textbook desert that its very name is just
the Arabic word for desert and it’s sometimes known as “The Great Desert.” The
Sahara spans nearly 9.5 million km (3.6 million miles) in Northern Africa,
making it the third-largest desert, after the Arctic and Antarctic. While the
Sahara does have ergs (or sand seas) and dunes can be over 180 m (590 ft) tall,
most of the geography is hamada, or rocky plains. The Sahara is comprised of
several “subdeserts,” such as the Libyan desert, which rivals the Atacama as
the world’s driest place.
6. Kalahari Desert
The Sahara is Africa’s most famous desert; in fact, it’s
probably the most famous desert in the world. That means that the Kalahari,
located in the southern portion of the African continent, gets relatively
little attention. Even though it’s not as expansive or as well-known as its
northern cousin, the Kalahari is impressive in its own right. Although only parts
of the Kalahari can be classified as a “true” desert, receiving less than 10
inches of rain per year, the Kalahari is thought to cover around nearly 1
million km (or 350,000 miles). Its age is also impressive: geological studies
show it seems to have been in existence since the continent of Africa was
formed, around 60 million years ago. Summers here reach extreme temperatures,
daily temperatures sometimes soaring close to 45°C (113°F). The Kalahari is
also notable for its characteristic red sands.
5. Gobi Desert
The Gobi Desert stretches for over 1 million km (500,000
miles) across northwestern China and southern Mongolia. The desert is a rain
shadow formation; the high peaks of the Himalayas block rain-carrying clouds
from the Indian Ocean from reaching the Gobi, resulting in an area that
receives annual rainfall of less than 8 inches; much of the precipitation the
desert does receive occurs in winter, as wicked winds blow in moisture from the
Siberian steppes. While there are some sand dunes, much of the Gobi is simply
barren or exposed rock. The Gobi’s climate is an extreme one, with frigid
winters and hot summers; temperatures can fluctuate as much as 35°C in the span
of 24 hours. More alarming is that the Gobi has been expanding at a rate of
about 3,600 km (1,390 miles) per year and dust storms have been increasing in
frequency over the last 20 years.
4. Arabian Desert
Much as the Sahara is the name on everyone’s lips when they
talk about deserts, the Arabian Desert is likely what everyone pictures. This
tract of 2 million+ km (900,000 miles) stretches through Yemen to the Persian
Gulf and Oman, to Jordan and Iraq. This vast swath of wilderness is home to
some isolated sand seas; the center of the desert is the Rub’al-Khali, one of
the largest continuous bodies of sand in the world. Since the area is so large,
it is possible to subdivide it into different regions; some areas receive 100
mm of rain per year, while other areas receive as little as 50 mm of rainfall.
Daytime temperatures soar and drop at night, sometimes to the point of
freezing. Record highs exceed 50°C (122°F). In addition, the desert receives
around 3,400 hours of sunshine per year, making it one of the sunniest places
on earth.
3. Patagonian Desert
South America has a reputation for tropical rainforests, but
the truth is that the topography of the continent is highly varied, from the
wetlands of the Amazon to the peaks of the Andes to the arid region of the
Atacama. But the Atacama isn’t the only desert in South America—not by a long
stretch. The Patagonian Desert, near the southern tip of the continent, is
actually the largest South American desert and the seventh-largest in the
world. Located primarily in Argentina, with small portions in Chile, the
Patagonian Desert forms 673,000 km (260,000 miles) of the region of Patagonia.
Like the Atacama, this desert lies in the rainshadow of the Andes. The weather,
however, is colder: the temperature averages just 3°C and rarely exceeds 12°C.
Winter lasts for 7 months of the year and even in summer, frost is common.
2. Atacama Desert
I’ve written a bit about the Atacama Desert before, but this
expanse in northern Chile is well-known for a number of reasons. First and
foremost, the Atacama is known as the driest place on the planet. Straddling
the area between 2 mountain ranges, the Andes and the Chilean Coastal
mountains, the Atacama exists in a double-rain shadow, which excludes it from
getting moisture from either the Pacific or Atlantic Oceans. It’s estimated
that the Atacama has experienced this aridity for at least 3 million years (if
not even longer), making it the oldest continuously dry area on earth. Data
suggest that, from 1590 to 1971, the Atacama experienced no significant
rainfall. These days, annual rainfall is about 15 mm (0.6 inches). The Atacama
has long been compared to Mars; film and television producers film Martian
settings in the desert and NASA researchers have used the Atacama as a test
location.
1. Antarctica
We typically think of deserts as hot, dry places like the
Sahara; in fact, when someone says “desert,” we often think of sand and sun.
But deserts, in their most scientific sense, are actually classified by the
amount of precipitation they receive. That means that cold polar places, which
receive relatively little snowfall, are actually deserts too. Using this
criteria, Antarctica is the largest desert in the world, averaging just 166 mm
(6.5 inches) of precipitation each year. The continent spans 14 million km (5.4
million miles), making this desert much larger than the Sahara. Although we’d
typically think of Antarctica as a “wet” place, thanks to an abundance of snow
and ice, the simple fact of the matter is that the temperatures on the
continent are so cold and the air is so dry that precipitation—as snow or
rain—just doesn’t happen.
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