DE LA SALLE COLLEGE Geography Department

Ms.Diane Sammut

TOPIC 4

NOTES

Deserts

2

We will be focusing on...

Page

What are deserts? 3

Characteristics of Hot Deserts 4

How do hot deserts form? 5

Desert landforms 6

Location of hot deserts 7

Animal and plant adaptations in hot deserts 8

People of the hot deserts 10

Desertification 12

Desert dangers 14

Case Study : Thar Desert, India 15

Characteristics of Cold Deserts 16

Cold deserts of the world 17

Animal adaptations in cold deserts 19

Plant adaptations in cold areas 20

Living in cold deserts 21

Blizzards 23

This topic will be addressing the following learning outcomes :

8.7 I can compare the landscape and climate of a hot and a cold desert and the adaptations of vegetation, animals and people to survive this environment.

8.8 I can explore how people exploit hot and cold deserts for economic use.

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What are DESERTS ?

We've all seen deserts in the movies. They are full

of miles and miles of sand dunes. However, not all

deserts are like this. Many deserts are rocky with

scattered plants and shrubs. There are even deserts

that are icy and cold.

Deserts are primarily defined by their :

lack of rain (they generally gets less then

250mm of rain in a year)

dry soil

little to no surface water

high evaporation (they are so dry that

sometimes rain evaporates before it can hit the

ground!)

living conditions are hostile for plant and

animal life

There are four types of deserts:

subtropical deserts (hot and dry all year-

round)

coastal deserts (cool winters and warm

summers)

cold deserts (long, dry summers and low

rainfall in the winter)

polar deserts (cold all year-round)

HOT IN THE DAY, COLD AT NIGHT

Because deserts are so dry and their humidity is so

low, they have no "blanket" to help insulate the

ground. As a result, they may get very hot during

the day with the sun beating down, but don't

hold the heat overnight. Many deserts can

quickly get cold once the sun sets. Some deserts

can reach temperatures of well over 38°C during

the day and then drop below freezing during the

night.

Location of hot deserts.

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Characteristics of HOT DESERTS Hot deserts are found near the tropics of Cancer

and Capricorn. The largest hot desert is the

Sahara in Africa which spans the whole width of

the continent.

Hot deserts have an extreme climate and

challenging environment. There is very little

biodiversity in hot deserts because of the harsh

climate. Few species are strong enough to survive

there. Plants and animals which do survive there

have adapted to difficult conditions. The living

components and the non-living components of the

hot desert rely on one another - a change in one will

lead to a change in the other.

The climate is very hot. Summer day time

temperatures can exceed 40°C. However, at night

the temperature can drop below 0°C.

The climate is very dry with less than 250 mm of

rainfall a year.

Hot deserts have two distinct seasons:

summer, when the temperature ranges

between 35-40°C, and

winter, when the temperature ranges

between 20-30°C.

Desert soils are thin, sandy, rocky and generally

grey in colour. They are also very dry. When it

does rain they soak up the water very quickly. The

surface of the soil may appear crusty. This is due to

the lack of rainfall. As it is so hot water is drawn up

to the surface of the soil by evaporation. As the

water evaporates, salts are left behind on the

surface of the soil.

WHAT ARE CLIMATE GRAPHS?

Climate graphs show average rainfall

and temperatures typically

experienced in a particular location.

The temperature is shown on a line

graph, and rainfall on a bar graph.

They are usually represented on the

same set of axes with the months of

the year along the base.

Hot desert landscapes.

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Deserts are formed by weathering processes.

Large variations in temperature between day and night

put pressure on the rocks which then break in pieces.

Although rain seldom occurs in deserts, there are

occasional downpours that can result in flash floods.

Rain falling on hot rocks can cause them to shatter and

the resulting pieces and rubble spread over the desert

floor are further eroded by the wind.

Wind picks up particles of sand and dust and moves

them along in sand or dust storms. Rocks are

smoothed down, while the grains end up piled high in

sand dunes.

How do hot desrts FORM?

Wind erosion process in the desert.

Wind forming sand dunes.

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Desert LANDFORMS

What is an OASIS? A lone palm tree and a spring in the middle of a sandy desert is the typical image that people have of an oasis. This is a fairly accurate picture, though an oasis can be small or very large. An oasis is any area in a desert that has a supply of freshwater and where plants can therefore grow.

Oases provide rest, shade, food, and water for nomads as they travel their territory and to other people following trade routes. Some peoples have considered oases to be sacred places.

An oasis may be permanent or temporary. A permanent oasis is found where an underground water source exists. Sometimes the water springs naturally from the ground. Other times it is so deep that people must drill down to reach it and bring it up to the surface. The origin of the water may be hundreds of miles away. The water flows underground until it comes to the surface at the oasis.

Some oases exist only temporarily because the water supply is not constant. In the Sahara of Africa, for example, dry streambeds called wadis sometimes fill with water, which allows plants to grow. An oasis in the Sahara desert– Libya.

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Where are hot deserts LOCATED? Deserts cover more than one-fifth of the Earth’s

land area, and they are found on every continent.

Hot deserts are mainly found around the Tropics

of Cancer and Capricorn. The hot deserts of the

world are located between 15° and

30° north or south of the equator, where the air

is sinking air. Air that rises due to the intense heat

at the equator divides to flow north and south.

Deserts are often found towards the west of

continents. Some deserts are found on the western

edges of continents. They are caused by cold ocean

currents, which run along the coast. They cool the

air and make it harder for the air to hold moisture.

Most moisture falls as rain before it reaches the

land.

HOT DESERTS OF THE WORLD

Sahara Desert

The Sahara Desert is the world's largest hot desert; it stretches over 3,500,000

square miles in Northern Africa. he Sahara is a desert located on the African

continent. It is the largest hot desert in the world, and the third largest desert

overall after Antarctica and the Arctic.

The Great Victoria Desert

The Great Victoria Desert stretches across 163,900 square miles in both South

Australia and Western Australia.

Arabian Desert

Summers in the Arabian desert are quite

intense; temperatures can reach as high as

129 °F.

Syrian Desert

The Syrian Desert stretches across 200,000 square miles and only received

about five inches of rain annually.

Kalahari Desert

The Kalahari Desert is a large, arid, sandy area in Southern Africa extending

350,000 square miles.

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The ability to adapt to arid conditions can mean the

difference between life or death for animals and plants

that live in the desert. Some animals ;

burrow deep underground in the heat of the

day

lie in the shade until late afternoon or early

evening

have evolved salt glands, which allow their

bodies to remove salts but not sweat so they

retain water

Most deserts have dry, arid climates with little to no

rain, so every living organism that lives there must

find a way to adapt, survive and thrive, or die.

At night, the desert comes alive. A universal

adaptation of desert living begins with an upside-

down day. Instead of sleeping at night, nocturnal

animals sleep during the hottest part of the day, only

to take up their business of hunting food during night

time. By sleeping in the day, usually in the shade

beneath rocks, in a burrow dug into the cool

underground or beneath the shade of a bush, they

preserve their body’s water. This applies to mammals,

insects and reptiles of the desert.

How do desert plants and and animals ADAPT?

Camel adaptations in the desert.

The Meerkat

9

Native Americans familiar with desert life could

always find water when it couldn’t be found on

land, by slicing open a cactus or taking pieces of

the cactus flesh and eat it. Some cactus can grow to

over 40 feet tall and live for up to 150 years in

conditions that would kill other plants. This tree-

like pillar cactus with arms that shoot out at 90-

degree angles before growing vertically, and seen

in many western movies, survives in the arid desert

because it stores enormous amounts of rainwater

inside its thick, fleshy arms and body, using it

slowly. Many cacti visibly expand during the rainy

season, which also helps them to grow. Some of

them also produces edible fruit that can made into

a fermented beverage for rainfall ceremonies.

Plant adaptations in the desert.

Desert cactus.

The prickly pear.

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PEOPLE of the hot deserts

Deserts are areas with fragile and limited resources.

Despite the harsh conditions people live in desert

areas, but their need for food and water presents many

challenges. The lack of water, food and other basic

means of living are not easily accessible. Still, some

civilizations have attained quite high living standards,

like that of Egypt and some are going well enough to

spend their life here, like Bedouin Arabs. However,

some like the Bushmen of the Kalahari desert are still

quite primitive in terms of living their lives and are

barely surviving.

THE TUAREGS

The Tuareg people are a large Berber ethnic group.

They principally inhabit the Sahara in a vast area

stretching from far southwestern Libya to southern

Algeria, Niger, Mali and Burkina Faso. Traditionally

nomadic pastoralists, small groups of Tuareg are

also found in northern Nigeria. The Tuareg speak the

Tuareg languages.

They have been called

the "blue people" for the

indigo-dye coloured clothes they traditionally wear

and which stains their skin. The Tuaregs have been

one of the ethnic groups that have been historically

influential in the spread of Islam and its legacy in

North Africa and the adjacent Sahel region.

The Tuareg have controlled several trans-Saharan

trade routes and have been an important party to the

conflicts in the Saharan region during the colonial and

post-colonial era.

The Tuaregs travel using camels. The Tuaregs reading Islamic scripture.

Blue coloured turbans worn by the Tuaregs..

Everyday life of Tuaregs.

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BEDOUIN ARABS

The Bedouin are a grouping of nomadic Arab people

who have historically inhabited the desert regions in

North Africa, the Arabian Peninsula, Iraq and the

Levant. The English word Bedouin comes from the

Arabic badawī, which means "desert dweller".

Bedouin territory stretches from the vast deserts of

North Africa to the rocky sands of the Middle East.

They are traditionally divided into tribes, or clans and

share a common culture of herding camels and

goats. The vast majority of Bedouin adhere to Islam.

Many Bedouins have abandoned their nomadic and

tribal traditions for a modern urban lifestyle, however

many retain traditional Bedouin culture such as

retaining the traditional tribe structure, traditional

music, poetry and dance.

Urbanised Bedouins often organise cultural festivals,

usually held several times a year, in which they

gather with other Bedouins. Traditions like camel

riding and camping in the deserts are still popular

leisure activities for urbanised Bedouins who live

close to deserts or other wilderness areas.

The Bedouins in Israel.

Bedouins making bread.

A Bedouin festival in the Sahara.

A typical Bedouin herding sheep.

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DESERTIFICATION — How does it happen?

Desertification is the expansion of desert into the

surrounding areas. The desert area in the world is

getting bigger. Desertification usually happens on

the edge of deserts ex. The Sahel, south of the

Sahara Desert in Africa.

WHAT CAUSES DESERTIFICATION?

Desertification is a complex process. It is caused by

physical processes and human mismanagement.

Factors which may cause desertification include:

climate change - especially long dry periods,

causing drought. The dry conditions cause the

vegetation to die, so the land loses the

protective cover that vegetation provides.

too many animals within the area - leads

to overgrazing.

population growth - leads to more pressure on

the land for growing crops. Nomadic tribes that

once moved around may start to farm in one

area. Wood is also used for buildings, heating,

and firewood, causing deforestation and soil

erosion.

The Sahel region.

People fighting desertification in Burkina Faso—West Africa.

Map showing areas around the world which are most affected by desertification.

Images showing the effects of desertification in Africa.

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WHAT ARE THE EFFECTS OF DESERTIFICATION?

lack of vegetation cover for holding soil together and

for grazing

increased soil erosion

crop failure, leading to famine

fewer plant and animal species

land is unable to support people so they are forced

to migrate

HOW CAN DESERTIFICATION BE SOLVED?

Recent evidence suggests that there are some areas where the process of desertification has slowed down.

However, the areas on the edge of deserts are still fragile and need very careful management.

Desertification in Syria.

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so plants have a chance to grow

again

____________________________

circles of stones are placed on the

ground to hold water on the soil

rather than let it run quickly across

the surface —this reduces soil

erosion

___________________________

providing shelter from the wind

____________________________

adding layers of leaves or straw

can reduce evaporation and add

nutrients to the soil when they rot

____________________________

soil is not washed down the slope

when it rains

_________________________

used to stabilise sand dunes

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Desert DANGERS Life in deserts is extremely difficult because of the lack of

water, limited food supply and extreme heat during the day

and cold during the night, and exposure to other elements.

In a desert area there are many environmental factors that

challenging :

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You find scorpions in in

many areas including deserts.

They are mostly nocturnal.

Scorpions typically brown or

black in moist areas, however

in the desert they may be

yellow or light green. Fatalities from scorpion stings are rare.

A bite from a scorpion may cause swelling, pain, nausea,

fever, and even speech and breathing difficulties.

Sandstorms occur frequently

in most deserts. Within Saudi

Arabia, winds typically range

from 3.2 to 4.8 kph. The

greatest danger is getting lost

in a swirling wall of sand.

People usually cover their mouth and nose with cloth.

Mirages are optical phenomena caused by the refraction of

light through heated air rising from a sandy or stony surface.

They occur in the interior of the desert about 10 kilometers

from the coast. They make

objects that are 1.5 kilometers or

more away appear to move. This

mirage effect makes it difficult

for you to identify an object from

a distance. The mirage effect

makes it hard for a person to identify targets and see objects

clearly. However, if you can get to high ground you can get

above the superheated air close to the ground and overcome

the mirage effect.

An extreme loss of water and salt

and your body's inability to cool

itself can cause heat stroke.

Persons may die if not cooled

immediately. Symptoms are the

lack of sweat, hot and dry skin,

headache, dizziness, fast pulse, nausea and vomiting, and

mental confusion leading to unconsciousness.

Some species of snakes have

specialized glands that contain a

toxic venom, and long, hollow

fangs to inject their venom.

Although venomous snakes use

their venom to secure food, they

also use it for self-defense. Human accidents occur when you

don't see or hear the snake, when you step on them, or when

you walk too close to them.

Desert survival kit.

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The Thar Desert is

located in northwest

India. It is one of the

major hot deserts of

the world with the

highest population

density. Many people

living in this desert

are farmers but with increasing development

opportunities, the human population is also growing.

Due to population pressures this environment is

increasingly under threat.

Despite having an extreme climate, the Thar Desert

can provide development opportunities. These

include:

Mining - the desert has valuable reserves of

minerals such as feldspar, phospherite, gypsum

and kaolin. These minerals are used to produce a

range of things from cement to fertilisers and are

therefore valuable. Limestone and marble are

also quarried in the area. Limestone is used for

building and producing cement, and marble is

used in construction.

Energy generation - energy is produced in the

Thar Desert using solar panels. This energy is

used to clean water supplies contaminated with

salt (desalination). Wind energy is also used to

generate electricity. A wind farm consisting of 75

wind turbines has the capacity to produce 60

megawatts of electricity.

Farming - irrigation in the Thar Desert has

made commercial arable farming (growing of

crops) viable. Producing crops such as wheat

and cotton has created many jobs and generated

income for the local economy.

Tourism - the Thar Desert National Park attracts

many visitors who want to see some of the 120

species found there. Tourists explore the desert

with local guides on camels. Tourism is an

important source of income and creates many

jobs for local people.

Case Study : THE THAR DESERT, INDIA

Desert safari—a popular activity with tourists.

The growing of crops in the Thar Desert.

Desert solar farm .

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Cold deserts, sometimes known as temperate

deserts, occur at higher latitudes than hot deserts,

and the aridity is caused by the dryness of the air.

Some cold deserts are far from the ocean and others

are separated by mountain ranges from the sea, and

in both cases, there is insufficient moisture in the air

to cause much precipitation.

Polar deserts are a particular class of cold desert.

The air is very cold (average annual temperature is

around -50°C) and carries little moisture so little

precipitation occurs and what does fall, usually

snow, is carried along in the often strong wind and

may form blizzards, drifts and dunes similar to those

caused by dust and sand in other desert regions. In

Antarctica, for example, the annual precipitation is

about 50 mm on the central plateau and some ten

times that amount on some major peninsulas.

WHY IS IT SO COLD AND DRY?

The angle of the Sun is low in the sky. This

means the energy from the Sun spreads out

over a large area.

The area has 24 hours of darkness for some of the

winter. Therefore, there is no sunlight for long

periods of time.

The surface of Antarctica has a high albedo. This

means that a lot of the energy received from the

Sun is reflected back into space.

The high altitude of the land. Temperatures

decrease approximately 1°C for every 100 m

increase in height.

Cold air cannot hold as much water vapour as

warm air, so precipitation is less likely.

Oceans store heat so they often create milder

temperatures and increased rainfall. However, as

Antarctica is such a large land mass most of

which is away from the sea.

Characteristics of COLD DESERTS

Typical climate graph for Antarctica.

The cold desert of the Himalayas.

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COLD DESERTS of the world The largest of these deserts are found in Central Asia.

Others occur on the eastern side of the Rocky Mountains,

the eastern side of the southern Andes and in southern

Australia.

GREENLAND

Greenland is the world’s largest non- continental and coldest desert. It is famous

for having the largest national park in the world, the Northeast Greenland

National Park. Temperature of Greenland remains between –8° to -3.88° Celsius.

GOBI

In Asia, Gobi covers the area of Mongolia as well as southern and western part

of China. Being situated on the enormous plateau, high altitude is one of the

major factors for its cold temperature.

ARCTIC

The Arctic circumscribes the North Pole of the world and extends into several

regions including Alaska, Canada, Greenland, Iceland, Norway, Finland,

Sweden, and Russia.

NAMIB

Namib is located in southern Africa and is known for its cold temperature. The

reason behind cold temperature is its location along the coast of Benguela

current. The interesting fact about it is that many shipwrecks can be found up to

50 meters inland ascribed to the movement of the desert.

TURKESTAN

The desert lies in the region of central Asia. Turkish people used to live here. The

cold desert is also home to gerbils, tortoises, and gazelles. Turkestan Desert is a

desert /semi-desert region of Turkmenistan, Uzbekistan, Kyrgyzstan, Tajikistan,

and southern Kazakh-stan. This 215,000 square mile desert covers five different

countries. Turkestan Desert is a cold desert and has long winters .

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ANTARCTICA

Antarctica is considered as the driest, windiest and coldest continent in the

world. In fact, the world’s coldest temperature was recorded at Vostok Station

in 1983 . The reason behind its weather is landmass elevation and ocean

temperatures.

ATACAMA

Atacama desert is situated in South America. It is

considered as the driest and non-polar desert in the

world. It is also noticed that the Atacama desert has

been described as very similar to Mars’ surface.

IRANIAN

The Iranian desert is famous for its marshes and seasonal lakes due to the

runoff from nearby mountains. Sand storms are very common in this area and

can form mound that reach up to 40 meters in height.

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ANIMAL ADAPTATIONS in cold deserts Cold desert animals, even the ones that also live in

hot and dry deserts, burrow into the ground to stay

warm. Dry desert animals burrow to stay cool.

Animals such as badgers, kit foxes, coyotes and

lizards also burrow into the ground. Only jack

rabbits tend not to. Cold desert animals usually

come out when the temperature is at its warmest.

Cold deserts are also populated by many small

mammals that horde food and are stingy about

what they eat. These include kangaroo rats,

kangaroo mice, pocket mice, grasshopper mice and

ground squirrels. Larger mammals such as

antelopes, deer and camels can also be found in

cold deserts.

Mammals are more likely to appear in cold deserts than

reptiles. With coats of fur and warm blood (meaning

that they can maintain a stable internal temperature

even when the ambient atmospheric temperature dips),

mammals are well-adapted to deal with freezing

winters. However, some lizards and snakes do make

their homes in certain cold deserts.

Polar bears are the world’s biggest land-based carnivores! They mainly eat seals but can hunt small whales. They are found across the Arctic Ocean, in parts of Canada, Alaska, Russia, Greenland and Norway (Svalbard).

Reindeer are a species of deer. They can be found in Northern Asia, Europe, Siberia, Alaska, Canada and Green-land.

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Like many cold environments, plants in cold deserts

tend to be deciduous. They also have spiny leaves,

which can help prevent evaporation or protect the

plant in the fight for scarce resources. Their shallow

and widely spread root systems help absorb as

much water as possible, so they tend to be widely

scattered. Plant height can vary between 6 to 48

inches. Cacti, sagebrush and ocotillo are a few of the

plants that make their home there. Only a select few

have managed to adapt to the harsh habitat.

How do PLANTS ADAPT in cold areas?

21

The Sámi are a groupSweden, Finland and

the Kola peninsula in Russia. of indigenous

people that come from the region of Sápmi, which

stretches across the northern parts of Norway,

No-one is exactly sure how many Sámi people there

are, but estimates range from between 50,000 –

200,000! On the 6 February every year, they

celebrate Sámi Peoples Day. They wear traditional

clothes, eat traditional food and fly the Sámi flag!

Their traditional outfits – known as the Gakti – are

worn at parties, festivals, weddings, baptisms,

funerals and more. The handmade outfits are

decorated with different designs so the Sámi can

easily tell where another person is from.

The Sámi are best known

for reindeer herding.

Reindeer meat is used for

cooking, leather and fur is

used to make shoes and

clothing, and antlers and

bones make useful tools

and decorative objects.

The Sámi are also skilled fishers and sheep

herders. Reindeer are so important to the Sámi way

of life, that many people go to a special university to

learn how to care for their animals. Like we might

have classes in Maths or English, they have classes

that teach them how to look after the reindeer herds –

how cool is that?!

There are nine different

Sámi languages!

Thankfully, the word

‘reindeer’ is the same

for all Sámi people,

meaning they can

communicate with each

other about reindeer, no matter what language

they’re speaking!

LIVING in cold deserts

The Sami people.

The regions inhabited by the Sami.

The love and care for reindeer.

Typical Sami clothing designs.

The Sami flag.

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In Frozen II, the make-believe Northuldra tribe you

see in the Enchanted Forest are based on the Sámi

people of northern Norway! During the film, Elsa

and Anna learn that their mother was one of the

Northuldra people, which makes the sisters half

Northuldran.

The Sámi are ‘semi-nomadic’, meaning they don’t

stay in the same place all year. Sámi herders migrate

with their reindeer during the seasons, heading to the

mountains for winter and coming back together with

the community in the summer. On the journey, Sámi

herders will camp in a traditional tent, called a lavvo.

A lavvo is a circular frame of poles leaning inwards

towards a pointy top – similar in style to the teepees

and wigwams used by the indigenous people of

America. Traditionally, the Sámi people lived in a

group of families called a ‘siida‘. The word siida is

used to describe both the reindeer herding area and

the team of people who look after the herd.

The Sámi people have their own parliaments to

represent them in Norway, Sweden and Finland, and

their own newspapers and radio stations, that

report on issues that concern the Sámi people!

Laipi—Sami typical bread and its recipe below..

The Northuldra people in Frozen II

The Sami Parliament in Norway.

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A blizzard is a powerful snowstorm. Low

temperatures, strong winds, and large amounts

of snow together create this dangerous weather

condition. During a blizzard, the driving snow can

make it difficult to see far.

During a blizzard the wind blows at speeds of more

than 56 kilometers per hour for at least three hours.

Visibility (the distance you can see) drops to 0.4

kilometre or less. When the weather conditions are

this bad, main roads and railways may have to be

closed, and power and telecommunications lines

may stop working.

In a severe blizzard, the wind speed increases to

more than 72 kilometres per hour. Visibility drops to

near-zero, and temperatures fall to −12 °C or lower.

When a severe blizzard becomes so bad that it is

impossible to see where the ground ends and the air

begins, it is called a “whiteout.” A ground blizzard

occurs when snow has stopped falling and high

winds are blowing around the fallen snow. Ground

blizzards are most common in wide, open fields or

flat spaces.

Blizzards often occur in cold places where winds

blow strongly—in Antarctica, for example.

However, these storms can happen almost anywhere

in the right conditions.

During the winter of 1962–63 the United Kingdom

suffered some of its most severe weather ever.

Blizzards left drifts of snow 6 meters deep. Roads

and railways were blocked, power lines fell down,

and communities were completely cut off.

In 1993 a blizzard so powerful that it was later called

the Storm of the Century struck the East Coast of

the United States. It affected 26 states and left 3

million people without power. Some places received

more than 1 meter of snow.

BLIZZARDS— dangers in cold areas

Aftermath of the Blizzard of 2015 Includes Floods, Destroyed Homes and Cars.

Effects of a blizzard.