Geography of Continents and Oceans.

1. Introduction.

Geography of the continents and the oceans studies continents, oceans, their geographical position, relief, climatic belts, natural zones, natural resources, peculiarities of vegetable and animal life, population, political map, inland waters. The greater part of the Earth’s surface is occupied by oceans, the smaller – by land. The total surface area of the Earth is 510 million sq km. The area of the land is 149 million sq km, which is only 29% (per cent) of the surface of the globe.

The oceans are linked and are really but one great ocean is called the World Ocean. There are five oceans on the globe: the Pacific Ocean, the Atlantic Ocean, the Indian Ocean, the Arctic Ocean and the Southern Ocean. Large landmasses, surrounded by oceans and seas are called mainland or continents. There are 6 continents:

There are 6 continents.	There are 6 parts of the world.
Africa Australia Antarctica North America South America Eurasia	Africa Australia Antarctica America Europe Asia

The largest continent is Eurasia. The largest ocean is the Pacific Ocean. The warmest ocean is the Indian Ocean. The smallest and the coldest ocean is the Arctic Ocean.

We broadened our knowledge about the life in the World Ocean. While we are studding separate continents and oceans we knew when and by whom they were discovered, who explored them, what people live there, what states are situated on them now. We need deep geographical knowledge in order to stop the pollution of nature. Thanks to this knowledge we understand that we are responsible for our planet on which we live.

Maps

Maps are the important source of geographical knowledge. Using maps you may determine the disposition of the continents, oceans, rivers, states. All geographical maps are divided into 3 groups: a) by scale; b) by scope of the territory; c) by content

Geographical Maps

Are divided:

by scope of

the territory by scale

maps of the world and hemispheres

large scale maps

maps of the separate continents

medium scale maps

maps of the parts of the continent

small scale maps

topographical maps

by content

all geographical maps

special maps

complex maps

The Birth of Maps.

The first primitive drawings looking like maps appeared long before people learned to write. Archeologists still find them on the walls of the caves, mammoth tusks and wooden tables. The most ancient pictures of areas were made 10-15 thousand years ago. Cartography as a science appeared in ancient Greece. In the III century BC a famous mathematician and geographer Eratosthenes counted the length of the circumference of the Globe at the meridian. He made up the map of dry land known in those times and showed meridians and parallels on it. Another mathematician, astronomer and cartographer Claudius Ptolemy, who lived in Alexandria in the II century AD, made a book called “The Guide in Geography”. The book determined the development of cartography until the XV century.

Geographical Envelope.

Geographical envelope is the inner envelope of the Earth in which the interaction of the upper parts of the Lithosphere with lower parts of atmosphere, hydrosphere and biosphere takes place. All the parts of Geographical Envelope interact with each other.

Lithosphere.

Lithosphere is an outer layer of the earth crust 10 or 100 km deep, ¼ of which forms land and ¾ - form oceanic bottom. It consists of 13 blocks, seven of which are very large (Pacific ocean plate, North American plate, South American plate, African plate, Eurasian plate, Indo-Australian plate, Antarctic plate). These blocks include the earth crust of the continents and oceans. Deep rifts separate the blocks from one another. In the places, where continental blocks come together, there are mountains. The blocks can move 1-6 sm a year. The movement of the blocks is connected with the movement of the mantle of the earth. Between the blocks of lithosphere there are active volcanoes and the earthquakes are frequent. These regions are called seismic belts. There are 3 layers in the Earth Crust:

• Sedimentary layer

• Granitic layer

• Basaltic layer

Atmosphere is the upper envelope of our planet. It is the mixture of gasses surround the Earth. The role of atmosphere is enormous.

Relief of the Earth.

Large territories of the dry land and oceanic cavities, vast plains and mountain ranges form an unusual surface of the Earth. Roughness of the Earth’s surface, which differs in size, origin and age is called the relief.

The largest forms of the relief on the Earth are continents and oceanic bottom. We distinguish two forms of relief on the continents: plains and mountains, and on the oceanic bottom – plains, mountains and oceanic cavities. The disposition of them depends on the peculiarities of the Earth Crust.

The Earth Crust consists of three layers (sedimentary, granitic and basaltic) on the continent and two layers (sedimentary and basaltic) on the oceanic bottom.

The Earth Crust consists of stable and unstable plots. The formation of the earth crust depends on outer and internal processes. Outer processes are: wind, waters, the sun, ice. Internal processes are: volcanoes, quakes.

Climate.

One of the main components of nature is climate. Climate is the total sum of weather during the period of years. The elements of climate are: temperature, rainfalls, atmospheric pressure and winds. There are four reasons, which influence climate:

1. geographical position;

2. relief;

3. oceanic currents;

4. circulation of atmosphere.

All the elements of climate are different in different parts of the globe. It depends on the belts of atmospheric pressure. There are three belts of low pressure and four belts of high pressure. The belts of atmospheric pressure form as the result of the distribution of sun warmth on the surface of the Earth and the influence of the rotation of the sun round its axis.

The highest temperature was marked in North America on the Mexican Highlands on 11 of August in 1933. In a shadow the temperature raised to +57.8^oC . In the Death Valley, California, on the 10 of June 1913close to that high temperature +56.7^oC was marked. The absolute minimum of temperature was noticed at “Vostok” station, Antarctica, in 1982. It was -89.2^oC. Before it in the northern hemisphere, the lowest temperature was found. In the winter of 1938 in Oimyakon the lowing of temperature to -77.8^oC was noticed.

Air Masses.

Air masses are large scope of air of troposphere with the same qualities.

There are four types of air masses on the Earth:

1. equatorial;

2. tropical;

3. temperate;

4. arctic and antarctic.

While moving the air masses conserve their qualities and determine the weather of the places they come to.

The predominant winds depend on the disposition of the belts of the atmospheric pressure. There are trade winds and west winds. They are constant. Monsoons are the winds of season character.

The belts of pressure and air masses can move. The system of large air currents of the Earth we call circulation of atmosphere.

Climatic Belts.

There are 13 climatic belts. They have different temperature conditions and air masses. Climatic belts are divided into main and transitional.

Main.	Transitional.
Equatorial 2 Tropical 2 Temperate Arctic Antarctic	2 Subequatorial 2 Subtropical Subarctic Subantarctic

• Equatorial climatic belt. In equatorial climatic belt all year round predominant equatorial air masses. Atmospheric pressure is low, temperature is high, the sum of rainfalls is large. There is 1 season.

• Tropical climatic belt. In tropical climatic belt predominant tropical air masses, high atmospheric pressure, temperature is high. Summer is cooler. It’s seldom rain. There are 2 seasons.

• Temperate climatic belt. In temperate climatic belt predominant temperate air masses, west winds. The sum of rainfalls is different in different places. There are 4 seasons.

• Arctic and Antarctic climatic belts. They are the coldest climatic belts. Climate here is severe. Atmospheric pressure is high, predominant arctic and antarctic air masses.

The transitional climatic belts are situated between the main climatic belts.

Natural Complexes.

Natural complex is a plot of the surface of the Earth, which differs with peculiarities of natural components. All the natural components are connected with each other. If we change one of them, the other changes too. The difference of natural complexes depends on mountain systems, relief and climate. Natural complex can be large or small. Continents are the largest natural complexes on the dry land.

Natural complexes form in the oceans too. They consist of the following components: water with soluble gases, plants, animals, rocks and the relief of the bottom. The world ocean is a huge natural complex. We can also find other natural complexes: oceans, seas, bays, straits, rivers, lakes and so on. There are many natural complexes both in the oceans and on the dry land.

Natural complexes on the dry land and in the oceans change in different directions: from the north to the south, from the coastlines far into the land, from the foot of the mountain to its top. It depends on climate, the structure of the earth crust, peculiarities of water masses and other reasons, which influence on the formation of natural complexes.

Natural zone is a large natural complex, which has common temperature conditions, moisture, soils, vegetation and animal world. Natural zones are on the dry land and in the oceans too.

Natural zones on the continent	Natural belts of the World Ocean
Arctic deserts Tundra and forest–tundra Taiga Mixed and deciduous forests Steppes and forest-steppes Deserts and semi-deserts Savannahs and rare forests Tough evergreen forests and shrubs Monsoon forests Wet evergreen forests High altitude zone	North pole North sub pole North temperate North subtropical North tropical Equatorial South tropical South subtropical South temperate South sub pole South pole

High Altitude Zone. The Andes.

We can see the changing of natural zones not only on the continents and oceans, but in the mountains as well. Temperature, pressure and rainfalls change on the height over the sea level. We can find different natural belts in the mountains.

In the mountains the natural zones change one goes up the slopes. At the foot of the mountains there is a natural zone peculiar for the surrounding plain. For example, near the equator there are equatorial forests, till altitude 1.200-1.500 m above sea level. Then come the mountain forests. The temperature here is + 12,+20C, rainfalls- 3.000 mm.Treefern, bamboo, cinchonatree grow here. At the height of 2.800- 3.800 m there are alpine forests. Alpine meadows re situated at the height of 4.500 m. Perennial snow and glaciers are at the height of 4.500m and more. The animal life is not rich here. We can see vicuna, chinchilla, condor.