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A DAY in the LIFE: DESERTS.

DID YOU THINK DESERTS WERE DULL ZONES? THINK AGAIN!

THE WORLD'S GROWING DESERTS

SANDSCRAPER

How high can they go? Sand dunes in Africa's Namib Desert reach up to 244 meters (800 ft) high, nearly as tall as Rockefeller Center in New York (850 ft.)

WHAT'S A DESERT?

A LAND AREA WHERE:

[check] less than 25 cm

[check] an extreme range of temperatures is the norm. In a single day in North Africa's Sahara Desert, the difference between day and night can be more than 50 [degrees] C (90 [degrees] F).

[check] evaporation (amount of water turning to vapor front the ground up exceeds precipitation (amount of water failing in the form of rain).

AND THE WINNER IS ...

Largest desert Africa's Sahara--more than 9 million sq km (3.5 million sq mi), roughly the size of the U.S.

Hottest Sahara--temperatures can reach 58 [degrees] C (136 [degrees] F)

Coldest Antarctica's dry polar deserts the mean annual temperature is about -17 [degrees] C (1.5 [degrees] F)

Least rain In Chile's Atacama Desert and Saudi Arabia's Arabian Desert, several years can pass virtually without a drop.

Most dunes Australia's Great Sandy Desert

TRAVELING SAND

Sand dunes are hills of loose sand that form where winds are strong and tend to blow in One direction. In deserts where wind blows in many directions, sand dunes may be slatshaped. In deserts with savage winds and little sand, like Peru's coastal deserts, dunes may be crescent shaped. In a single day, a desert sand dune can move or travel 8 cm (3,2 in), or as much as 30 m (100 ft) a year.

How much loose sand makes up...

[GRAPH OMITTED]

Sand desert, called erg, covers about 20 percent of Earth's deserts. The rest is divided between hammada (bare rock) and reg, broad plains covered by loose gravel or pebbles.

Deserts cover nearly 25 percent of Earth's land surface, and are growing. Desertification is the process of fertile land turning into barren desert due to climate change or human causes, like overplowing or deforesting land.

OPERATION DESERT STORM

In a single day, thunderstorms can transform the desert landscape through flash floods, produced by a lot of rain over a small area. Water rushes quickly over dry, rocky ground that can't absorb much water. Sometimes the flood's force moves car-size boulders. Deep channels called arroyos can form if enough water carves through desert ground. Over thousands of years, arroyos can form deeply carved valleys or canyons.

CHECK OUT WHAT IT TAKES TO SURVIVE

BEAT THE HEAT

The North American kit fox and Saharan fennec fox (above) have normal body temperatures, and radiate excess desert heat from blood vessels in their large ears, like heat from a radiator.

HOT FOOT

Daily exercise for the common collared lizard (Crotophytus collaris): Lift one or two front feet off the ground to keep tootsies cool. Once cool, place feet back on ground, then lift the hind two.

HIGH AND DRY

The saguaro cacti in Arizona's Sonoran Desert can reach heights up to 12 meters (40 ft). That's two stories high!

THORNY CACTUS

Cacti are succulents, plants with fleshy stems and/or leaves containing large amounts of water. The family contains 1,650 species, and are native only to American deserts.

HOW CACTI THRIVE IN DESERT DROUGHT:

* Roots spread out just below the ground surface to collect rain water or dew after a cold night.

* They store water in barrel-shaped, ribbed stems that expand as they fill.

* A waxy coat covers leaves to help prevent water loss.

* Thorny spines protect a cactus from hungry animals in search of a water supply.

* Among plants, cacti have the unique ability to take in and store carbon dioxide ([CO.sub.2]) at night. So their stomata (surface openings) stay open. Dining the day, the stomata close. Cacti use stored [CO.sub.2] during photosynthesis, the process in which plants convert sunlight energy

SAND DANCING

Instead of slithering on hot sand, sidewinding snakes fling their bodies in the air in a series of sideways moves

A TRUNK OF WATER, PLEASE

Thirsty? Baobab trees (also called "bottle trees") in the African Kalahari and Australian deserts store water in hollow trunks. More than 1,000 liters (1,057 quarts) have been found in a single trunk.

HAIR CONDITIONING

Camel fur traps a layer of air to keep the animal cool by day and warm at night. A camel's hump contains fat (not water), which stores enough energy for the camel to travel long distances without food or water. When it does find water, a camel can gulp 115 liters (122 quarts) in a few minutes!

BETWEEN A ROCK AND A HOT PLACE

During the day, scorpions (and many other desert animals) hide under rocks or in deep burrows. They come out to hunt and dine at night.

BETWEEN A ROCK AND A HOT PLACE

During the clay, scorpions (and many other desert animals) hide under rocks or in deep burrows. They come out to hunt and dine at night.
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Title Annotation:facts about deserts
Publication:Science World
Article Type:Brief Article
Date:Mar 8, 1999
Words:834
Previous Article:FAKE BLOOD Ready to Flow.
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