“How the name Earth does not correspond to our planet!
How much more correct would it be to say "Ocean" (Arthur Clarke) - about
87% of the Earth's surface is covered with water (Nikolaikin, 2006).
The ratio of land area to water surface on Earth:
a) the oceanic hemisphere; b - continental-oceanic hemisphere
1

The area occupied by the hydrosphere on the Earth's surface
Components of the hydrosphere
Square
million km2
%
World Ocean (seas and oceans)
361,2
70,8
Glaciation
16,3
3.2 (̴11% land)
Lakes and rivers
2,3
1,7
Wetlands and wetlands
3,0
0,59
Other
-0,2
-0,04
Snow cover (December, February)
̴60.0
̴11.8
Total
̴443
̴86.9
The concept of "hydrosphere" includes all the free waters of the Earth that are not chemically and




2

The water cycle

water is in constant motion
evaporates from the surface of water bodies, soil, plants
water accumulates in the atmosphere
falls in the form of precipitation, replenishing reserves in the oceans, rivers, lakes, etc.
complete renewal of the composition of water in the atmosphere occurs in 9-10 days
Thus, the amount of water on Earth does not change, it only changes its forms, this is the water cycle in nature.
3

Annual balance of water in the World Ocean
Parish elements
Quantity
km3
Precipitation
407200
river runoff
40000
underground runoff
(passing the rivers)
2400
Melted waters of the polar
regions
3000
Total
452600
Expense elements
Quantity
km3
Evaporation
452600
Total
452600
It is no coincidence that the oceans and seas are identified with the hydrosphere - they form it
bulk or more than 90%
4

Precipitation

5

Dependence of vegetation type on climatic conditions
* ARIDITY (DRYNESS) (from the Latin aridus - dry) - a set of conditions of existence, manifested
in the lack of moisture in the air and soil, which is a consequence of a significant excess of evaporation over
6
the amount of precipitation.

Water properties

Water is both an acid and a base at the same time (H+ cation
anion OH-), has the same concentration of hydroxide ions and
hydrogen ions.
One Million Dollar Bonus Announced for the Tested
experience demonstrating the memory of water has not been obtained by anyone.
7

The concept of "hydrosphere" includes all the free waters of the Earth that are not chemically and
physically with the minerals of the earth's crust.
The hydrosphere consists of all oceans, seas, rivers, lakes, reservoirs, swamps, groundwater, glaciers,
snow cover, includes atmospheric and soil moisture, as well as biological water
(for example, the human body contains about 70% water).
8

Fresh water

Fresh water makes up 2.5% of all water reserves on planet Earth
The amount of water that mankind can realistically count on now and in
in the nearest future:
– The amount of fresh water available is only in the thousands of cubic meters.
kilometers. Most of the fresh water on the earth's surface is stored in
lakes -176.4 * 10 3 km3.
- If for a moment to delay the flow of all the rivers of the globe, it would turn out that
that in their channels there is simultaneously 2120 km3 of water.
- The sources of many rivers, large and small, are in swamps that contain
10300 km3 of fresh water.
- 13,000 tons of water is contained in the layers of the atmosphere closest to the earth's surface.
At an altitude of up to 1 km, the concentration of water vapor in the air is on average
2%.
– Within the framework of the program of the International Hydrological Decade 1964-1974
gg. the calculation of the amount of water on Earth is made with all accuracy,
accessible to modern science.
– The results of this work were published in the multi-volume work "World Water
resources and water balance of the globe"
9

10. Water quality

Solid - ice
According to the state they distinguish:
Liquid - water
Gaseous - water vapor
Losing 10-20% of body weight is life-threatening
The average person consumes 2 to 4 liters of water per day.
Suitable fresh water with a total mineralization of up to 0.5 - 1 g / l
10

11. Effluent regulation

Complete renewal of the composition of water in the atmosphere occurs in 9-10 days
11

12.

12

13.

13

14.

Growth in specific water consumption
14

15. Urgency of the threat of water scarcity

The minimum amount of water required for one person to drink,
15
hygiene and food cultivation

16.

16

17. Precipitation: as a source of water resources

17

18. fresh water resources

18

19.

19

20.

The world's water resources are under great strain due to
population growth and rising incomes
This amount of water is required to produce
one pair of cotton jeans - approx.
20

21.

GROWTH IN THE WORLD FISH FIT
Over the past 50 years, fish production has increased 5 times
21

22.

22

23.

EXAMPLE OF FISH GRINDING IN ECOSYSTEM
As a result of overfishing, the number of trophic levels in food webs is decreasing. When it doesn't stay
large individuals of slowly growing predators (police), fishermen catch smaller specimens. Unlike
old saithe young are not so large as to feed on cod that eats whiting, and he, in turn, -
haddock (left). They are forced to eat even smaller fish (herring), whose main food is krill (right).
Thus, the destruction of large pollock shortens the food chain to four trophic levels, which
destroys the structure of the ecosystem.
23

24.

Aral degradation
24

25.

The Aral Sea has gone 100 km from
its former coastline
25

26.

26

27.

Water consumption by crops
(number of precipitation and irrigation water per season, mm)
REDUCTION AND GROWTH IN CATCH SIZES (T)

The most important morphological feature of the modern surface of the Earth is the uneven distribution of land and sea on the earth's surface with a decisive predominance of water space.

The ratio of land and water areas on the earth's surface is 1: 2.43. VI Vernadsky believed that in the geological past this ratio could vary from 1.93 to 7.79. From the indicated change in the ratio of land and sea, it is assumed that during geological time the volume of the waters of the World Ocean remained unchanged. At present, this assumption is unbelievable. The change in the geological past of the volume of the waters of the hydrosphere, along with the geotectonic development, determined the constant change in the ratio between land and sea.

According to N. M. Strakhov, as the distance to the geological past, the area of ​​the seas on the platforms decreased due to the increasing spread of deep geosynclinal seas. Regarding the early stages of geological history, it is known that shallow seas prevailed in the Precambrian and Lower Paleozoic times. A. B. Ronov gives data on the areas occupied by geosynclinal and platform seas from the Lower Devonian to the Lower Jurassic. The data obtained by Ronov are in good agreement with data on changes in the ratio of land and sea in the geological past, obtained by another method. A comparison of them shows that in the Triassic the land occupied the largest surface, but later it began to give way to the growing area of ​​sea spaces. The predominance of the areas of sea basins, which has increased sharply since the Jurassic, can be connected with the expansion and deepening of the oceans that began at that time. We can speak of a directional change in the ratio of the area of ​​land and sea on the earth's surface, which was determined by the tectonic development of the earth.

The idea of ​​a heterogeneous distribution of land and water over the earth's surface, of its division into continental and water hemispheres, developed as early as the 18th century. On the mainland hemisphere at present, land occupies 39.3% of its surface, and water 60.7%; in the oceanic hemisphere, water accounts for 80.9% and land for 19.1%. Of interest is the ratio of the average depths of the oceans in these hemispheres. In the continental hemisphere, the average depth is 3320 m, in the oceanic hemisphere 4070 m. Comparing the average height of the land with the average depth of the ocean for the continental and oceanic hemispheres, we find that it is significantly different, the difference in the average height of the continents for both hemispheres is 450 m. Even more great the difference between the average height of the land and the average depth of the oceans. This value gives an idea of ​​the amplitude of the dissection of the earth's surface. For the continental hemisphere, this difference is 570 m, and for the oceanic hemisphere, 3270 m. Note that, according to Cossipa, the average level of the earth's crust in the continental hemisphere is 1420 m, and in the oceanic hemisphere, 2346 m. ​​Consequently, the masses of the earth's crust in the continental hemisphere are raised, and in the oceanic lowered in relation to the average level (2440 m) of the earth's crust.

It is remarkable that the above difference for the continental and oceanic hemispheres is equivalent and amounts to 1020 m. Consequently, the distribution of masses of the earth's crust and the associated distribution of land and water in the continental and oceanic hemispheres do not represent a surface phenomenon on Earth, but reflect the state of isostatic equilibrium between the masses of the earth bark. This is quite clearly confirmed by V. I. Vernadsky, who drew attention to the fact that the modern ratio of land and water areas on Earth (2.4-2.5) corresponds to the ratio of the specific gravity of continents and oceans (taken to the average depth of the World Ocean). This circumstance emphasizes the isostatic equilibrium in the distribution of continental and oceanic areas on the earth's surface. In the state of modern isostatic equilibrium of continental masses and oceans, researchers saw an expression of a fundamental difference in their geological nature. They believed that the continents are lighter, formed from sialic material, in comparison with the bottom of the oceans, which is composed of denser simatic masses.

It is assumed that such a difference in the structure of the continents and the bottom of the oceans is due to the antiquity of the oceans and the existing isostatic equilibrium - a state that has long been established. This opinion is contradicted by the ratio of land and sea that has repeatedly changed in the geological past. It was determined by the tectonic development of the Earth and was accompanied by a significant movement of the masses of the earth's crust. Under these conditions, it seems absolutely improbable that the isostatic equilibrium of the continents and oceans will remain unchanged. There is no doubt that in the course of geological time this balance was disturbed and its current state was determined by the youngest - neotectonic and modern tectonic movements. This means that the ratio of land and oceans, corresponding to a certain stage in the development of structure and relief, is not a long-term phenomenon.

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What is dry land? This is that part of the earth's surface that is not hidden by water bodies, ranging from the world's oceans to lakes, rivers and reservoirs. Thus, land can be understood as any part of the mainland or island that is not flooded with water.

Some statistics

What is the percentage composition of the land of our planet? A little less than a third of it is given to forests (about 27%), even less (21%) - to pastures of natural origin, a little less than 10% is occupied by arable land and the same amount - by irrationally used lands.

Another 11% each falls on deserts and glaciers. Most of the latter lies, as you might guess, in Antarctica. Cities occupy in total no more than 1% of the entire land area of ​​the Earth.

How much land area on Earth is according to scientists? The vast majority of the surface of our native planet is reserved for the body of water, called the oceans. And only 29% of it is occupied by the continents, which in numerical terms equals approximately 149 million square kilometers. They are based on the earth's crust, its thickness varies in different places from 25 kilometers or more. Modern geography recognizes as continents 6 main and largest areas into which the land of planet Earth is divided: Africa, Eurasia, South and North America, as well as relatively small Australia and Antarctica.

Who is bigger?

The championship in size, as is known from the school geography course, belongs to Eurasia, stretching with its intricately broken coastline from Cape Roka in the west to Cape Dezhnev in the east for all 16,000 kilometers. Its territory is more than 50 million square meters. km. And this is the only continent, standing on the coast of which, you can admire the view of one of any four world oceans.

Second place in the ranking of "The largest land on the planet" confidently holds Africa. Its midline (about half the distance between the extreme northern and southern points) is located almost exactly on the equator. From the north, only the narrow Isthmus of Suez connects the mainland with the aforementioned champion Eurasia.

North America is in third place. It lies entirely in the northern hemisphere and occupies a little over 24 million square meters. km from the territory that represents the entire land of the planet. Three oceans (Atlantic, Pacific and Arctic) wash its shores. The Bering Strait, which serves as a natural border between it and Eurasia, as scientists think, did not exist in the deepest antiquity: in its place was an isthmus connecting the continents.

Other continents

Another America (South) is located mainly in tropical and equatorial latitudes. Its coastline is less indented, and the area of ​​\u200b\u200bthe mainland washed by the waters of the Atlantic and Pacific oceans (and from the north - the Caribbean Sea), together with all the islands, is about 17.8 million square meters. kilometers. It is the fourth largest landmass on the planet.

Who is the outsider in this ranking? The smallest of the continents is Australia (only 7.6 million square kilometers). Its territory is located completely below the equator line. There are no land links between this small green continent and the rest, from which Australia is far removed.

Antarctica is kept somewhat apart from fellow continents. This is the most sparsely populated of all the parts into which the land of the planet is divided. And it is not surprising, because its entire territory (which is about 14 million square kilometers) lies completely below the Antarctic Circle, and the geographical center of the continent practically falls on the South Pole. The entire area of ​​the mainland is entirely hidden under an impenetrable layer of ice and snow.

Planet Earth: land and water

What do we know about the oceans? Of the 4 water giants that our planet has, the leadership in size and depth, of course, belongs to the Pacific. Its total volume is over 1300 million cubic kilometers, and the area with all the seas is more than 170 million square kilometers. km. If its average depth is about 4,000 meters, then the maximum is more than 11,000 meters. On its territory, moreover, the largest cluster of islands.

The smallest of the oceans is the Arctic Ocean, only 4% of the Earth's water surface is reserved for it. It is 3 times smaller than the other three giant oceans. In addition, it is the most difficult to access. This is due to the multi-year ice layer with a thickness of more than 4 meters. Through it, a path was laid, called the Northern Sea, along it you can get from the European part of our native country to the Far East.

Terrestrial land: the formation of continents

From school, each of us knows in detail the outlines of the continents and the largest islands. But they weren't always like that. Scientists have long ago proved that the Earth's lithosphere is made up of tectonic plates, the destiny of which is to move along the mantle lying under them.

The age of our globe, according to scientists, is approximately equal to four and a half billion years. Already in the Archean era (the oldest in earth's history), the Earth consisted of oceans and continents, the outlines of which, however, were far from modern. And then, and in our days, the continental crust was formed and is being formed from rocks melted in the depths of the earth's interior and brought to the surface.

What determines the contours of the Earth

The entire lithosphere is represented by tectonic plates capable of approaching, diverging and mutually colliding. During these collisions, any of them can go deeper, plunging under the next one. Active volcanoes and deep ditches form in the areas of such dives.

In the same place, where there is a divergence of plates, deep cracks cross the earth's crust. The rocks melt to form basalts, which rise up to fill these cracks and solidify in the upper layers of the Earth's crust. In place of the ocean, when the plates diverge, an ocean floor with underwater ridges is formed.

In the past, most of the modern southern continents existed together in the form of a giant mainland, called Gondwana by scientists. The connection of the ancient continents occurred during the Paleozoic era, which began at a time mark of about half a billion years ago from the current one, and continued for about 300 million years.

grand union

At the end of this period, the movement of tectonic plates led to the connection of Gondwana with other continents. The result was a huge dry land, uniting almost all the ancient continents.

Scientists geologists gave the name to this single continent - it was Pangea, it was located from the North to the South Pole. The mountain systems that currently exist in North America, Asia, and Australia are the result of the convergence of tectonic plates.

The division of the single continent of Pangea into separate continents began hundreds of millions of years later. As a result, the land of the planet (continents) and the oceans, with their outlines, little by little approached those that we are accustomed to observing on modern geographical maps.

For many years, geologists doubted the plausibility of the theory of continental drift, that is, the ability of continents to approach and move away. But the scientific data collected in the sixties of the last century dispelled these doubts.

Why is it so?

The outer shell of the earth (lithosphere), being solid and extending deep into the globe up to a hundred kilometers, consists of tectonic plates. These plates can move because, deep in the lithosphere, the Earth's mantle is a much more liquid high-temperature substance that supplies energy for the movement of tectonic plates.

Now the number of large and medium lithospheric plates is about 10. These include the Eurasian, African, Pacific and others. They move at a speed of several centimeters annually. This is how the process of separation of America, Europe and Africa began about 180 million years ago. At the same time, an ocean formed between them, now called the Atlantic.

Looking at a modern map of the world, one can see that the coastal contours of the continents separated by the Atlantic Ocean coincide quite accurately. Of course, such a coincidence is not the only argument in favor of the theory of the separation of the continents. Scientists have collected evidence using the latest scientific research in the field of geology and oceanography.

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