Hot deserts
Climate and characteristics
Desert soils tend to be sandy or stony
Desert climates have extreme
with little organic matter and a lack
temperature range. During the day the
of dense vegetation. The soils are dry
temperature may reach 50˚C, at night
but can soak up water rapidly after
however temperatures can fall to below
rainfall.
0˚C.
Evaporation draws salts to the surface,
Deserts also have very little rainfall, with
often leaving a white residue on the
less than 250mm of rainfall per year. This
ground. All this means that desert soils
rain can also be very unreliable.
are not particularly fertile.
There are three factors Living in the desert
which form desert areas:
1. Mountain ranges to
create rain shadows,
meaning only very
dry air moves beyond
the mountains.
2. High pressure areas
(due to sinking air),
creating cloud free
conditions.
3. Cold ocean currents.
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Hot deserts
Vegetation adaptations
Plants have adaptations to help then survive (live
Some desert plants have shallow roots to get
and grow) in different areas. Adaptations are
water when it soaks into the surface. Other
special features that allow a plant or animal to
plants have very long tap roots to get to the
live in a particular place or habitat. These
water deep in the rocks as the soil on the
adaptations might make it very difficult for the
surface is very dry.
plant to survive in a different place. This explains
why certain plants are found in one area, but not Some desert plants have small waxy leaves to
another. For example, you wouldn’t see a cactus reduce transpiration. Needles are also thin
living in the Arctic, nor would you see lots of really and mean there is less water loss so precious
tall trees living in grasslands. water is saved.
Some desert plants flower directly after the
rain to drop their seeds and then they
disappear.
Saguaro Cacti are well adapted for survival in the desert. They have:
stems that can store water
widespread root systems that can collect water from a large area
spines instead of leaves, minimising the surface area and reducing water loss by
transpiration
spines to protect it from animals that might eat it.
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Hot deserts
Hot desert location
Hot deserts are generally located in dry continental
interiors in belts following the 30 degrees north and
30 degrees south lines of latitude.
These latitudes are where air that has risen at the
equator descends forming a persistent belt of high
pressure. This location is associated with a lack of
cloud and rain and high daytime temperatures. This
lack of cloud cover means very cold nights.
In the United States, the largest desert in the Great Basin Desert. The Great Basin Desert
is not the type of desert you would normally picture. It is unique because it receives
most of its precipitation as snow!
The Sahara Desert.
Blanketing much of the northern third of the African continent, or some 3.5 million
square miles, the Sahara Desert extends eastward from the Atlantic Ocean some 3,000
miles to the Nile River and the Red Sea, and southward from the Atlas Mountains of
Morocco and the Mediterranean shores more than 1,000 miles to the savannah called the
Sahel. More than 16 times the size of France, the Sahara Desert covers nearly all of
Mauritania, Western Sahara, Algeria, Libya, Egypt and Niger, the southern half of Tunisia
and the northern parts of Mali, Chad and Sudan.
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Hot deserts
Animal adaptations
Animals have to adapt to living in the desert.
Camels have adapted to living in the desert in the following
ways:
Animals in the desert have evolved
long eyelashes keep out dust physically and behaviourally to
tough mouth for eating thorny plants survive. They must ensure they can
large padded feet to stop sinking into the sand avoid heat, find water, retain water
stores water in stomach and ensure survival against
tail scares flies away predators.
light colour to reflect heat
hair on back for shade.
The Jerboa mouse has adapted to living in the
desert by:
being active at night and sleeping during
the day
having huge ears to help it stay cool.
The Thorny Devil lizard has adapted to living in the desert by:
having sand coloured skin to camouflage into the sand
growing hard spikes to stop other animals from eating it
having spikes which helps it to get water (in the morning it rubs against dew
drops and the moisture runs between the spikes along grooves that run directly
into its mouth).
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Hot deserts
Climate and characteristics Vegetation adaptions
Hot desert location Animal adaptions
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Hot deserts
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