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The Sahara (Arabic: صحراء, French: Sahara) is the largest desert on Earth, located in North Africa. Extends approximately 4800 km from west to east and from 800 to 1200 km from north to south; has an area of about 8.6 million km² (about 30% of the area of Africa, slightly larger than the area of Brazil). From the west, the Sahara is washed by the Atlantic Ocean, from the north it is bounded by the Atlas Mountains and the Mediterranean Sea, and from the east by the Red Sea. The southern border of the desert is defined by a zone of sedentary ancient sand dunes at 16° N, to the south of which is the Sahel, a transition region to the Sudanese savannah. Sahara
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The landscape of the Sahara is very diverse. There are 4 types of relief here: tectonic - structural plains, island mountains, highlands and depressions between them; erosive – remnants of eroded structural plains, dry riverbeds – wadis; water-accumulative - ancient alluvial plains and lake depressions (shotts, sebkhs) and aeolian - ergs. These morphostructural elements correspond to certain types of deserts: rocky (hamads), pebble (regs), sand-pebble (serir), sandy (ergs) and saline (sebkhs).
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“A land shining with lifeless beauty and ideal desert...” Albert Camus Ergi The Saharas are not dried up seas, as was previously thought. They were formed from sandy deposits that once accumulated along the shores of ancient giant lakes or at the mouths of long-vanished rivers. In the Nubian Desert there are so-called fossil ergs, so ancient that the dunes that fell off were petrified, turning into ridges of layered sandstone. Erg Chebbi, Morocco.
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The country of thirst and horror - Hamads The rocky deserts of the Sahara (hamads), occupying up to 70% of its area, are often devoid of higher vegetation. Cushion-shaped freodolia and limonastrum bushes are established only on isolated stone screes. The more humid deserts of Central Asia, although sparsely, are evenly covered with wormwood and solyanka. Low-growing saxaul thickets are common on the sandy-pebble plains of Central Asia. In tropical deserts, succulents settle on rocky surfaces. In South Africa these are cissus with thick barrel-shaped trunks, milkweed, and “tree lily”; in the tropical part of America - a variety of cacti, yuccas and agaves. In rocky deserts there are many different lichens that cover stones and color them white, black, blood red or lemon yellow. Scorpions, phalanges, and geckos live under the stones. Cottonmouth is found here more often than in other places.
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Serir Clay desert is a widespread type of desert developed on marine, lake, and river clay deposits of the arid zone. On surfaces composed of salt-bearing rocks (marls and clays), salt marshes with halophytes are formed, on less saline soils and in the deltas of ancient rivers - takyrs, almost devoid of vegetation or with a sparse cover of algae.
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The endless Sahara Desert has become synonymous with a hot, barren place where there is no life. In fact, this is not so - the interesting local ecosystem has long been able to adapt to existence in such extreme conditions, although, of course, it is not easy for humans to survive here. However, people also live in the Sahara, but an unprepared person in these inhospitable regions will definitely not last long.
LESSON
THE WORLD AROUND
3 CLASS
TEACHER: MUDRAKOVA E.I.
Lesson topic
DESERT
AFRICA
Research objectives
- Is there water in the desert?
- What animals live there?
Rules for working in a group
- work together;
- do not interrupt each other;
- listen to the opinions of others;
- evaluate the work of the group.
What are the natural conditions of the Sahara Desert?
- Located in northern Africa
- Surface sandy, clayey
- Little precipitation
- The air is dry and hot
- Temperature up to 50C in the shade
- Sand heats up to 70 C
- Samum
- Dunes
- Mirages
heavy
harsh
difficult
good
lungs
suitable
Oasis - an island of vegetation in the desert located near a natural reservoir
Desert flora
What is characteristic of desert vegetation?
-small leaves or scales;
- leaves-thorns;
-long root
Desert fauna
Game
"Get to know me"
1 group
Pygmy gerbil
Egyptian cobra
Lizard
2nd group
Jerboa
scarab beetle
Gazelle
3 group
Camel
Locust
Scorpion
Desert fauna
Protective painting
Hibernation
Ability to run fast
Undemanding to food and water
Reflection
Research objectives
- What are the natural conditions of the desert?
- Is there water in the desert?
- What plants grow in the desert?
- What animals live there?
- work together;
- work calmly, do not disturb others;
- do not interrupt each other;
- listen to the opinions of others;
- justify your point of view;
- evaluate the work of the group.
"Ladder of Success"
1st step– I didn’t understand the new knowledge, didn’t remember anything, I was left with many questions; I couldn’t cope with independent work in class;
2nd and 3rd steps– I still have questions about a new topic, mistakes were made in independent work;
4th step– I have mastered the new knowledge well and can share it; I have not made any mistakes in my independent work.
Homework
1. Write a mini-essay on one of the topics:
"One Day in the Desert" ,
"Can a Man Live in the Desert?"
2. Prepare a report about one of the representatives of the flora or fauna of the desert.
Sahara DesertCompleted by geography teacher of State Budgetary Educational Institution of Secondary School No. 68
Molchanova Lyudmila Stepanovna
St. Petersburg
The Sahara stretches across much of North Africa, covering 9 million square kilometers. In fact, the Sahara Desert covers 30% of the entire African continent. It is the hottest and hottest place in the world with summer temperatures that often exceed 57 degrees Celsius. The desert experiences annual rainfall and very powerful sandstorms, lifting sand 1000 meters into the air and moving the dunes.
Some say that the Sahara Desert was much larger before the first ice age, and some say that the Sahara Desert appeared 4,000 years ago. For example, German scientists, using methods of computer modeling of the Earth's climate, found that the Sahara became a desert 4,000 years ago. 10 thousand years ago, the world's largest desert was covered with grass and low bushes, but then the summer became hotter and the rains almost stopped. Naturally, many ancient civilizations disappeared, and all living things left the Sahara. According to scientists from the Potsdam Institute for Climate Research, the transformation of the Sahara into a desert was one of the most dramatic climate events on Earth in the foreseeable millennia. Why is the climate so variable? It turns out that the inclination of the earth's axis to the Sun is gradually changing: approximately 9 thousand years ago it was 24.14 degrees, now it is 23.45 degrees. Today the Earth comes closest to the Sun in January, ten thousand years ago at the end of July. Subtle changes in the Earth's orbit around the Sun, amplified by interactions with the atmosphere, ocean and land, change the climate beyond recognition.
The climate of the Sahara is extraordinary. The humid factor is the wide position of the Sahara north and south of the Tropic of the North. This explains the fact that most of the desert is influenced by the northeast trade wind throughout the year. An additional influence on the climate is exerted by the Atlas mountain barrier located in the north, stretching from west to east and preventing the bulk of humid Mediterranean air from penetrating into the desert. In the south, from the Gulf of Guinea, wet masses freely enter the Sahara in summer, which, gradually drying out, reach its central parts. Extreme dryness of the air, a huge moisture deficit and, accordingly, extremely high evaporation are characteristic of the entire Sahara. According to the precipitation regime in the Sahara, three zones can be distinguished: northern, central and southern.