The opposite of oceans is deserts. What can you tell about them except that it is very hot and dry there?

A) The main desert regions on our planet are the following (I think you have heard about them some time ago at school, but I'd like to remember you about them):

Arabian - covering most of the Arabian Peninsula.
Atacama - running down the western coast of South America (in Chile).
Australian - hot deserts covering much of western and central Australia.
Iranian - northeast of the Arabian Peninsula and west of the Thar Desert.
Kalahari - covering much of the south-eastern tip of Africa.
Namib - running down the south-western coast Africa.
North American - rain shadow deserts in south-western North America, in the USA and Mexico.
Patagonian - in south-eastern South America.
Saharan - a huge desert covering much of northern Africa - the biggest desert in the world.
Takla Makan-Gobi - a continental desert in central Asia, mainly in Mongolia and north-western China.
Thar - in northwest India.
Turkestan - in Turkmenistan.

B) What do you know about flora and fauna of deserts? What peculiarities do they have?

C) Can you tell anything about the climate of desert regions?

D) And now read this text to be sure that everything you have told about deserts before is correct.

Something about deserts Deserts cover about one fifth of the Earth’s surface and occur where rainfall is less than 50 cm/year. Although most deserts, such as the Sahara of North Africa and the deserts of the south-western U.S., Mexico, and Australia, occur at low latitudes, another kind of desert, cold deserts, occur in the basin and range area of Utah and Nevada and in parts of western Asia. There are four major types of deserts: 1). hot and dry; 2). semiarid; 3) coastal and 4). cold. Temperatures and precipitations. Hot and dry deserts are characterized by extremely high temperatures in summer (sometimes about 50ºC above zero) and very low rate of rainfalls. Sometimes rain starts falling and evaporates before reaching the ground. The other types of deserts also have a very low level of rainfalls. But the level of condensation of dew caused by night cooling may even exceed the rainfall received by some deserts. But these regions receive a little more than twice the solar radiation received by humid regions. The northerner a desert is the colder and longer winters are and summers become much shorter and not so warm. Vegetation. Most deserts have a considerable amount of specialized vegetation, as well as specialized vertebrate and invertebrate animals. Soils often have abundant nutrients because they need only water to become very productive and have little or no organic matter. Disturbances are common in the form of occasional fires or cold weather, and sudden, infrequent, but intense rains that cause flooding. Vegetation is very poor. Plants are mainly ground-hugging shrubs and short woody trees. Leaves are very small and covered with a thick cuticle (outer layer). Cool nights help both plants and animals by reducing moisture loss from transpiration, sweating and breathing. Very often they have a form of a spine. The spiny nature of many plants in semiarid deserts provides protection in a hazardous environment. The large numbers of spines shade the surface enough to significantly reduce transpiration. Some plants have extensive root systems close to the surface where they can take advantage of any rain showers. Many plants of semiarid deserts have silvery or glossy leaves, allowing them to reflect more radiant energy. These plants often have an unfavourable odour or taste. In costal deserts all of the plants with thick and fleshy leaves or stems can take in large quantities of water when it is available and store it for future use. In some plants, the surfaces are corrugated with ridges and grooves. When water is available, the stem swells so that the grooves are shallow and the ridges far apart. As the water is used, the stem shrinks so that the grooves are deep and ridges close together. The plants of cold deserts are widely scattered. One of the most widespread plants is sagebrush. Plant heights vary between 15 cm and 122 cm. The main plants are deciduous. Fauna There are relatively few large mammals in deserts because most are not capable of storing sufficient water and withstanding the heat. Deserts often provide little shelter from the sun for large animals. The dominant animals of warm deserts are nonmammalian vertebrates, such as reptiles. Mammals are usually small, like the burrowers and kangaroo rats of North American deserts. The animals include small nocturnal (active at night) carnivores. There are also insects, arachnids, reptiles and birds. The animals stay inactive in protected hideaways during the hot day and come out to forage at dusk, dawn or at night, when the desert is cooler. In semiarid deserts one can find such as the kangaroo rats, rabbits, and skunks; insects like grasshoppers and ants; reptiles are represented by lizards and snakes; and birds such as different kinds of owls and eagles. Among animals of costal deserts one can find coyote and badger, great horned owl, golden eagle, bald eagle. Amphibians that pass through larval stages have accelerated life cycles, which improves their chances of reaching maturity before the waters evaporate. Some insects lay eggs that remain dormant until the environmental conditions are suitable for hatching. Fauna of cold deserts is represented by different kinds of mice, rabbits, ground squirrels, badgers, kit foxes, and lizards. Almost all of them are burrowers. Deer are found only in winter.

surface – поверхность rainfall – осадки low latitude – низкие широты semiarid – полузасушливый   low rate – низкий уровень to evaporate – испаряться solar radiation – солнечное излучение humid – влажный, сырой   vegetation – растительность vertebrate animals – позвоночные животные invertebrate animals - беспозвоночные животные abundant nutrients – изобильные питательные вещества ground-hugging shrubs – цепляющиеся за почву кусты cuticle – кутикула, кожица to reduce moisture loss – сокращать потери влаги transpiration – испарение spine – иголка, колючка бот. hazardous – опасный glossy leaves – глянцевые, блестящие листья fleshy – мясистые corrugated with ridges and grooves – изборожденные складками stem shrinks – ствол сморщивается to scatter – разбрасывать sagebrush – полынь deciduous – бот. лиственный mammal – млекопитающее to withstand – противостоять shelter – укрытие reptile – рептилия burrower – обитатель нор nocturnal carnivore – ночное плотоядное животное arachnid – паукообразное насекомое hideaway – убежище to forage – добывать еду skunk – скунс lizard – ящерица snake – змея badger – барсук amphibians – земноводные larval stage – стадия личинки maturity – зрелость dormant – спящий  to hatch – высиживать

 

Answer the questions.

1. How are all the deserts divided and why?

2. What are the temperatures in different kinds of deserts?

3. Why do the leaves of desert plants usually have a form of a spine?

4. What else help plants keep water?

5. Why aren’t there large animals in deserts?

6. What kinds of animals are mostly spread there?

7. Why are there a lot of nocturnal animals?

8. How can amphibians and insects overcome hazardous conditions of life?