Desert animals need to keep their bodies as cool and moist as possible.
Many only come out at night when the desert cools down
and have special features and types of behaviour to help them live more
easily in the hot, dry desert conditions during the day:
There are two types of camel - a dromedary has one hump on its back and a bactrian camel has two humps. They:
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Clouds hardly ever form in deserts because the air is so warm that it can hold lots of water vapour without it condensing. This makes rain very rare.
The Atacama desert in northern Chile is the driest
desert on Earth. Parts of the desert had no rain for 400 years, from
1570-1971, and in other parts, rain has never been recorded.
With no clouds to block the Sun's rays, the ground becomes baking hot. Surface temperature of at least 40oC are not uncommon. At 57oC,
Death Valley is the driest, hottest place in North America. Gold
prospectors died there, in 1849, when they ran out of food and water on
their way to the Californian goldfields - which is how the valley got
its name.
Nights can be very cold, though, and even frosty in winter, because cloudless skies let heat escape.
Strong trade winds blow across the deserts. In sandy deserts, the wind sweeps up fine sand and causes dust storms up to 3,000m high.
As sand is blown along, it erodes rocks in its path. Over many years,
the rocks may be sand-blasted into weird, sculptural shapes.
The total rain for the year usually falls in just two or three heavy storms. The
water does not soak in straight away, but runs rapidly across the
surface, sweeping up valley debris and carrying it along wide channels
called wadis. Deep canyons may be formed too.
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Deserts are dry, barren areas where less than 25cm of rain falls each year. They are mostly located in tropical areas, between about 15o and 30o north and south of the Equator.
Deserts are found in areas where dry winds blow
across the land. These can be a long way from the sea, where moist sea
winds do not reach (e.g. the Gobi desert in Asia). They can also be in
areas separated from the sea by high mountains, called the rainshadow
(e.g. the Atacama desert in Chile).
There is little to protect a desert from the action of the
wind. Strong winds pick up fine surface debris and blast it again exposed rock,
eroding it away to form rock pillars and isolated hills - such as Ayers Rock
(Uluru) in Australia.
 
The most common dunes found in sandy deserts are called barachans.
They
are crescent-shaped and may be up to 30m high. As sand is blown up one
side and slips down the other, these dunes can creep forward between 10
and 50m a year and can engulf villages.
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Huge areas of rainforest are cleared each year:
Although deforestation helps countries develop and can create new jobs, some people worry that it will be bad because it will:
In recent years, more sustainable ways of using the rainforests have been developed to help conserve and protect them:
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The Kayapo people are a tribe of about 8,638 indigenous (native) peoples who live in the Amazon Rainforest. They like to call themselves Mebengokre, meaning 'the men from the water place'.
The Kayapo tribe live alongside the Xingu River in several scattered villages
ranging in population from one hundred to one thousand people. They
have small hills scattered around their land and the area is
criss-crossed by river valleys. Their villages are typically made up of about dozen huts. A centrally located hut serves as a meeting place for village men to discuss community issues.
Their appearance is highly decorative and colourful, using: face and body paint, beads and feathers. The Kayapo believe their ancestors learnt how to live communally from social insects such as bees,
which is why mothers and children paint each other's bodies with
patterns that look like animal or insect markings, including those of
bees. Men wear the flamboyant Kayapo headdress with its outwardly
radiating feathers (representing the universe) at ceremonies to mark the
changing of seasons as well as rites of passage.
The Kayapo people use shifting cultivation
where land is farmed for a few years, after which the people move to a
new area. New farmland is cleared (using cutting and burning) and the
old farm is allowed to lie fallow and replenish itself. Crops they grow
include: weet potatoes, yams and papaya.
Since the initial arrival of Europeans around 500
years ago, the Kayapo have experienced forced migration further west
into the rainforests. They have lost: land, habitat and they have also
suffered from the introduction of diseases from the outsiders.
The Kayapo are keen to preserve the rainforest and since 1989 they have worked with The Body Shop to raise awareness about the destruction of the Amazon.
They have also been involved in protests against the building of hydroelectric dams on their land. Despite the prospects of new job opportunities and the providing of an essential power supply to the area, they argued that:
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Various
tribes of people live in the tropical rainforests, such as: the Pygmies
in central Africa, the Lumad peoples in the southern Philippines and
the Amazonia Indians of South America. Whilst some are keen to trade high value forest products such as: animal hides, feathers, and honey with agricultural people living outside the forest, others prefer to remain elusive - it is believed that there are 67 different uncontacted tribes in Brazil and 44 on the island of New Guinea, for example.
Different tribes of rainforest people live different lifestyles:
Many people who live in rainforests find that using boats on rivers is the easiest way to travel around.
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A diverse range of millions of different animal species live in the rainforests because there is plenty of: food, water and warmth for them.
Arboreal animals that live among the branches need to be able to move from tree to tree whilst only small creatures live on the forest floor because they can move about the tangled shrubbery more easily than larger animals.
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