Hydrosphere
Hydrosphere - the totality of all the waters of the Earth: continental (deep, soil, surface), oceanic and atmospheric. Sometimes the waters of the oceans and seas are combined into a kind of part of the hydrosphere - oceanosphere. This is logical, because the vast majority of water is concentrated in the oceans and seas.
The emergence of water on Earth is usually associated with the condensation of water vapor from volcanic eruptions that have occurred since the beginning of the formation of the planet. Evidence of the presence of water in the geological past are sedimentary rocks with horizontal layering, which reflects the uneven deposition of mineral particles in the aquatic environment. Such rocks are known and their age dates back to 3.8-4.1 billion years. However, the appearance of drop water could have been earlier - in the air, on the surface of the planet, in the voids of rocks. In order for water to be concentrated in the depressions of the earth's surface and form pools, flooding of the initially dehydrated rocks had to occur. Primary waters were highly mineralized, which is associated with the dissolution of various substances in them that were released along with water vapor during volcanic manifestations. Fresh water came later. It is possible that an additional source of water on Earth was icy comets that invaded the atmosphere. Such a process is observed at the present time, as well as the formation of water during the condensation of vapors from volcanic eruptions.
Despite the diversity of natural waters and their different state of aggregation, the hydrosphere is one, because all its parts are connected by ocean and sea currents, channel, surface and underground runoff, as well as atmospheric transport. The structural parts of the hydrosphere are given in Table. 5.3.
Physical and chemical properties of water. Water is the most amazing substance in the world. Despite the fact that A. Celsius used for the temperature scale the melting point of water as 0 ° and its boiling point as 100 °, this liquid can freeze at a temperature of 100 ° C and remain liquid at -68 ° C, depending on the oxygen content and atmospheric pressure. It has many anomalous properties.
Fresh water is odorless, colorless, and tasteless, while seawater is tasteful, colorless, and may have an odor. Under natural conditions, only water occurs in three states of aggregation: solid (ice), liquid (water) and gaseous (steam).
The presence of salts in water changes its phase transformations. Fresh water on land at a pressure of one atmosphere has a freezing point of 0°C and a boiling point of 100°C. Sea water at a pressure of one atmosphere and a salinity of 35‰ has a freezing point of about -1.9°C and a boiling point of 100.55°C. The boiling point depends on atmospheric pressure: the higher the height above the ground, the lower it is. Water is a universal solvent: it dissolves more salts and other substances than any other substance. It is a chemically resistant substance that is difficult to oxidize, burn or decompose into its constituent parts. Water oxidizes almost all metals and destroys even the most resistant rocks.
Table 5.3 The volume of water and the activity of water exchange in various parts of the hydrosphere
| Parts of the hydrosphere | Volume | Duration of conditional water exchange | ||
| thousand km 3 | % of total volume | % of fresh water volume | ||
| World Ocean | 96,5 | - | 2500 years | |
| The groundwater | 23 700 | 1,72 | 30,9 | 1400 to 10000 years in the permafrost zone |
| Glaciers | 26 064 | 1,74 | 68,7 | 9700 years |
| lakes | 0,013 | 0,26 | 17 years | |
| soil moisture | 16,5 | 0,001 | 0,05 | 1 year |
| The waters of the atmosphere | 12,9 | 0,001 | 0,037 | 8 days |
| swamps | 11,5 | 0,0008 | 0,033 | 5 years |
| reservoirs | 6,0 | 0,0004 | 0,016 | 0.5 years |
| Rivers | 2,0 | 0,0002 | 0,006 | 16 days |
When water freezes, it expands, increasing its volume by about 10%. The density of fresh water is 1.0 g / cm 3, sea - 1.028 g / cm 3 (at a salinity of 35‰), fresh ice - 0.91 g / cm 3 (therefore, ice floats in water). The density of other bodies (except for bismuth and gallium) increases during the transition from a liquid to a solid state. Water has a high specific heat capacity, i.e. the ability to absorb a large amount of heat and heat up relatively little at the same time. This property is extremely important, since water stabilizes the planet's climate.
The anomalous properties of water are explained by the structure of its molecule: hydrogen atoms are attached to the oxygen atom not "classically", but at an angle of 105 °. Due to the asymmetry, one side of the water molecule has a positive charge, while the other has a negative charge. Therefore, the water molecule is an electric dipole.
The processes where water is involved are extremely multifaceted: photosynthesis of plants and the respiration of organisms, the activity of bacteria and organisms that generate from water (mainly sea water) to build their skeletons or accumulate chemical elements (Ca, J, Co), nutrition processes and anthropogenic pollution and many more.
World ocean (oceanosphere)- a single continuous water shell of the Earth, which includes oceans and seas. Currently, there are five oceans: Pacific, Atlantic, Indian, Arctic (Arctic according to foreign classifications) and Southern (Antarctic). According to the international classification, there are 54 seas, among which there are domestic and marginal.
The volume of waters of the World Ocean is 1340-1370 million km3. The volume of land rising above sea level is 1/18 of the volume of the ocean. If the surface of the Earth were completely flat, the ocean would cover it with a layer of water of 2700 m.
The waters of the World Ocean make up 96.5% of the volume of the hydrosphere and cover 70.8% of the planet's surface (362 million km 2). Due to the huge water mass, the World Ocean has a great influence on the thermal regime of the earth's surface, acting as a planetary temperature regulator.
The chemical composition of the waters of the oceans. Sea water is a special type of natural water. The water formula H 2 O is also true for sea water. However, in addition to hydrogen and oxygen, seawater contains 81 of the 92 naturally occurring elements (theoretically, all naturally occurring elements of the periodic table can be found in seawater). Most of them are found in extremely low concentrations.
1 km 3 of sea water contains about 40 tons of dissolved solids, which determine its most important property - salinity. Salinity is expressed in ppm (0.1%) and its average value for ocean waters is 35‰ . Water temperature and salinity determine density sea water.
The main ones that are part of sea water are listed below.
1. solids, components an average of 3.5% (by weight). Most of all, sea water contains chlorine (1.9%), i.e. over 50% of all dissolved solids. Followed by: sodium (1.06%), magnesium (0.13%), sulfur (0.088%), calcium (0.040%), potassium (0.038%), bromine (0.0065%), carbon (0.003%) . The main elements dissolved in sea water form compounds, the main of which are: a) chlorides(NaCl, MgCl) - 88.7%, which give sea water a bitter-salty taste; b) sulfates(MgSO 4 , CaSO 4 , K 2 SO 4) - 10.8%; in) carbonates(CaCO 3) - 0.3%. In fresh water, on the contrary: the most carbonates (60.1%) and the least chlorides (5.2%).
2. Biogenic elements(nutrients) - phosphorus, silicon, nitrogen, etc.
3. Gases. Sea water contains all atmospheric gases, but in a different proportion than air: nitrogen prevails (63%), which, due to its inertness, does not participate in biological processes. This is followed by: oxygen (about 34%) and carbon dioxide (about 3%), argon and helium are present. In those sea areas where there is no oxygen (for example, in the Black Sea), hydrogen sulfide is formed, which is absent in the atmosphere under normal conditions.
4. Trace elements present in low concentrations.
Geographic patterns of distribution of water temperature and salinity. The general regularities of the horizontal (latitudinal) distribution of temperature and salinity on the surface of the World Ocean are shown in fig. 5.9 and 5.10. Obviously, the water temperature decreases in the direction from the equator to the poles, and salinity is characterized by a pronounced minimum in the equatorial region, two maxima in tropical latitudes, and lower values near the poles. The alternation of centers of low and high salinity near the equator and in the tropics is explained by the abundance of atmospheric precipitation in the equatorial zone and the excess of evaporation over the amount of precipitation near the northern and southern tropics.
The water temperature decreases with depth, as shown in Fig. 5.11 for the North Pacific. This pattern is typical for the World Ocean as a whole, however, changes in water temperature and salinity differ in its individual parts, which is explained by a number of reasons (for example, the season). The greatest changes occur in the upper layer to a depth of 50-100 m. With depth, the differences are erased.
water masses- this is a large volume of water that forms in a certain area of \u200b\u200bthe World Ocean and has relatively constant physical, chemical and biological properties.
According to V.N. Stepanov (1982), the following water masses are distinguished vertically: superficial, intermediate, deep and bottom.
Among the surface water masses, there are equatorial, tropical(northern and southern), subtropical(northern and southern), subpolar(subarctic and subantarctic) and polar(Arctic and Antarctic) water masses (Fig. 5.12).
The boundaries of various types of water masses are the boundary layers: hydrological fronts, zones divergences(discrepancy) or convergence(convergence) of water.
Surface water interacts most actively with the atmosphere. In the surface layer, intensive mixing of water occurs, it is rich in oxygen, carbon dioxide and living organisms. They can be called the waters of the "oceanic troposphere".
Along with surface currents (see Fig. 7.11), countercurrents, subsurface and deep water movements, as well as vertical mixing, tidal currents, and level fluctuations exist in the World Ocean.
Rice. 5.9. Average annual temperature (°C) of the surface of the World Ocean (according to V.N. Stepanov 1982): 1 - isotherms; 2 - areas of maximum water temperature; 3 - areas of water temperature below the average value (average water temperature 18.56 ° C)
Rice. 5.10. Average annual salinity (‰) of the surface of the World Ocean (according to V.N. Stepanov, 1982): 1 - isohalines; 2 - areas of maximum salinity; 3 - areas of salinity below average; 4 - areas of minimum salinity (average salinity 34.7 8‰)
Rice. 5.11. Graphs of the vertical temperature distribution characteristic of the arctic (1), subarctic (2), subtropical (3), tropical (4) and equatorial (5) water types
The relief of the bottom of the oceans. In the relief of the bottom of the World Ocean, the following structures are distinguished: shelf(mainland shoal), usually limited by the 200 m isobath, continental(continental) slope to a depth of 2000-3000 m and bed of the ocean. According to another classification, there are: littoral(and sublittoral), bathyal, abyssal(Fig. 5.13). Plots With depths over 6000 m make up no more than 2% of the area of the ocean floor with a depth of less than 200 m - approximately 7%.
Rice. 5.12. Ocean fronts and surface water masses of the World Ocean (according to V.N. Stepanov, 1982): types of water masses: Ar- arctic; SbAr- subarctic; SbTs - subtropical Northern Hemisphere; Ts- Tropical Northern Hemisphere; E- equatorial; Chu - tropical southern hemisphere; SbTu- subtropical southern hemisphere; SbAn - subantarctic; An - Antarctic; Tar- Arabian Sea; 715 - Bay of Bengal. The names of the oceanic fronts are shown in the figure
Rice. 5.13. Schematic division of the ocean floor
The role of the oceanosphere. Various (thermal, mechanical, physical, chemical, etc.) processes taking place in the vast (more than 70% of the Earth's surface) water area of the World Ocean have a significant impact on the processes taking place on land and in the atmosphere. The chemical elements that make up sea water are involved in the processes of gas, mass and moisture exchange at the boundaries of the hydrosphere - lithosphere - atmosphere. Hydrochemical processes affect the flora and fauna of not only the ocean, but the planet as a whole. Constant gas exchange with the atmosphere regulates the Earth's gas balance: the content of carbon dioxide in sea water is 60 times greater than in the atmosphere.
land waters, despite the relatively small volume, they play a huge role in the functioning of the geographical envelope and the vital activity of organisms. It should be noted that not all land waters are fresh, there are salt lakes and springs. The ionic composition of fresh and sea water is given in Table. 5.4.
Rivers- the most active representative of the fresh waters of the land. Rivers include permanent and relatively large watercourses. Smaller streams are called streams. The relief, geological structure, climate, soils, vegetation affect the regime of rivers and shape their natural appearance. The river has source - where it starts and mouth- the place of direct confluence of the river into the receiving body of water (lake, sea, river). The mouth can branch out, forming delta rivers. The area of land through which a river flows is called channel. The main river and its tributaries set up a river system. Rivers flowing into the oceans form estuaries- vast areas of mixing river and sea water. Estuaries are largely influenced by ocean waters.
Table 5.4. Ionic composition of river and sea water (according to P. Weil, 1977)
| ions | river water | Sea water (salinity 35‰ ) |
| Cations | ||
| Na+ | 0,27 | 468,0 |
| K+ | 0,06 | 10.0 |
| Mg2+ | 0,34 | 107,0 |
| Ca 2+ | 0,75 | 20,0 |
| Sum | 1,42 | 605,0 |
| Anions | ||
| Cl - | 0,22 | 546,5 |
| HCO3- | 0,96 | 2,3 |
| SO 4 2- | 0,24 | 56,2 |
| Sum | 1,42 | 605,0 |
The nature of the flow of rivers is associated with their food, which is rain, snow, glacial and underground, and is determined by the climatic conditions in the river basin. Rivers predominantly fed by snow have a pronounced spring flood and summer low water (Volga, Dnieper, Danube, Northern Dvina, Amur, etc.). Underground feeding smoothes the annual runoff. Rain-fed rivers often have a maximum runoff in different seasons of the year. The areas of the earth's surface and the thickness of soils and soils, from where the river receives food, is called catchment.
Rivers perform significant work, eroding the channel, transporting and depositing erosion products - alluvium. They not only mechanically destroy, but also dissolve rocks. River deposits sometimes form vast alluvial plains with an area of millions of kilometers (Amazonian, West Siberian lowlands, etc.). It is estimated that 2,100 km 3 of water is simultaneously in the rivers, while 47,000 km 3 annually flows into the ocean. This means that the volume of water in the rivers is updated approximately every 16 days. For comparison, we point out that the waters of the World Ocean carry out a large circulation in about 2500 years.
lakes- a natural body of land with a slow water exchange, which does not have a direct connection with the ocean. For its formation, the presence of a closed depression of the earth's surface (hollow) is necessary. The lakes occupy a total area of approximately 2 million km 2, and the total volume of their waters exceeds 176 thousand km 3. According to the conditions for the formation of the basin, the size, the chemical composition of the waters, and the thermal regime of the lakes are very diverse. Many artificial lakes have also been created - reservoirs(about 30 thousand), the volume of water in which is more than 5 thousand km 3. Approximately half of the lake waters are saline, and most of them are concentrated in the largest drainless lake - the Caspian Sea (76 thousand km 3). Of the fresh lakes, the largest are Baikal (23 thousand km 3), Tanganyika (18.9 thousand km 3), Upper (16.6 thousand km 3). The regime of lakes is characterized by heat inflow, water level fluctuations, currents, water exchange conditions, ice cover, etc. Large lakes largely determine the climatic conditions of adjacent territories (for example, Lake Ladoga).
swamps- these are land areas characterized by excessive moisture, stagnant or weakly flowing water regime and hydrophytic vegetation. They occupy an area of 2.7×10 6 km 2 , or about 2% of the land surface. The volume of swamp waters in the world is about 11.5 km 3, which is 5 times higher than the one-time volume of water in rivers. The emergence of swamps is associated with both climatic conditions (excess moisture) and the geological structure of the territory (proximity to the water-resistant horizon), which contribute to the swamping of land or the overgrowth of water bodies. In some areas of temperate and subpolar latitudes, permafrost plays the role of an aquiclude. A specific formation of swamps is peat.
The groundwater- these are waters that are in rocks in a liquid, solid or gaseous state. According to recent studies, the water content in rocks within the lithosphere exceeds the data indicated in Table. 5.3, and is about 0.73 - 0.84 billion km 3. This is only half as much as it is contained in the seas, oceans and surface waters, including the world's ice reserves. Water accumulates in all sorts of voids - channels, cracks, pores. It has been established that below the groundwater level to a depth of 4–5 km or more, almost all voids in rocks are filled with water. According to deep drilling data, water in the voids of rocks is located at a depth of more than 9.5 km, i.e., below the average level of the bottom of the World Ocean.
The totality of watercourses (rivers, streams, canals), reservoirs (lakes, reservoirs) and other water bodies (swamps, glaciers) is hydrographic network.
Land waters have been greatly transformed by man due to irrigation, melioration, plowing of land and other urban processes, in connection with which the problem of drinking water has become acute.
The complexity of its solution lies in the fact that the demand for clean water is growing, while its reserves remain the same. Used in in everyday life, in industrial and agricultural cycles, fresh water most often returns to the river network in the form of wastewater, treated in different ways or not treated at all.
Water forms the water shell of our planet - hydrosphere(from the Greek words "gidor" - water, "sphere" - a ball). It includes water in three states - liquid, solid (ice, snow) and gaseous (steam). Currently, water occupies 3/4 of the Earth's surface.
The hydrosphere includes three main components: World Ocean, sushi water and water in the atmosphere. All parts of the hydrosphere are interconnected by the process of the water cycle in nature already known to you.
The oceans account for over 96% of all water on our planet. Continents and islands divide it into separate oceans: Pacific, Atlantic, Indian, Arctic. In recent years, the maps highlight the Southern Ocean - the body of water surrounding Antarctica. The largest in area is the Pacific Ocean, the smallest is the Arctic Ocean. The parts of the oceans that jut out into the land are called seas. There are a lot of them. The largest seas of the planet are the Philippine, Arabian, Coral.
Water in natural conditions contains various substances dissolved in it. In 1 liter of ocean water, on average, contains 35 g of salt (most of all table salt), which gives it a salty taste, makes it unsuitable for drinking and use in industry and agriculture.
Land waters are rivers, lakes, swamps, glaciers and groundwater. Most of the waters of the land are fresh, but among the lakes and groundwater there are also salty ones.
You know what a huge role rivers, lakes, swamps play in nature and people's lives. But here's what is surprising: in the total amount of water on Earth, their share is very small - only 0.02%.
Much more water is contained in glaciers- about 2%. Do not confuse them with the ice that forms when water freezes. Glaciers are formed from snow. They occur where there is more snow than it has time to melt. Gradually, the snow accumulates, compacts and turns into ice. Glaciers cover about 1/10 of the land. Where are they located? First of all, on the mainland Antarctica and the island of Greenland, which are covered with huge ice shells. Blocks of ice that break off along their shores form floating mountains - icebergs. Some of them reach enormous sizes. Large areas are occupied by glaciers in the mountains, especially in such high places as the Himalayas, the Pamirs, and the Tien Shan. The beauty of the mountain peaks, covered with ice and snow all year round, is unique!
Glaciers are formed by fresh ice, and therefore they can be called pantries of fresh water. So far, it has hardly been used, but scientists have long been developing projects to transport icebergs to arid regions in order to provide local residents with drinking water.
The groundwater also make up about 2% of all water on Earth. They are located in the upper part of the earth's crust. These waters can be salty and fresh, cold, warm and hot. Often they are saturated with substances useful for human health and are medicinal (mineral waters). In many places, for example, along the banks of rivers, in ravines, groundwater comes to the surface, forming sources(they are also called springs and keys). Groundwater reserves are replenished by precipitation that seeps through some of the rocks that make up the earth's surface. Thus, groundwater is involved in the water cycle in nature.
Water in the atmosphere is water vapor, water droplets, ice crystals. Together they make up fractions of a percent of the total amount of water on Earth. But without them, the water cycle on our planet would be impossible.
Test your knowledge
- What is the hydrosphere? List its constituent parts.
- What oceans form the World Ocean of our planet?
- What is called the sea?
- What makes up land water?
- How are glaciers formed and where are they located?
- What are ground waters?
- What is water in the atmosphere?
Think!
- How is the ice in the Arctic Ocean different from the ice in Antarctica?
- What is the difference between a river, a lake and a swamp?
- What is the danger of an iceberg?
- Are there salt water bodies on our planet other than seas and oceans?
- What is the importance of water in the atmosphere?
- Find on the map the seas washing the shores of our country. Name them.
Each of the spheres of the planet has its own characteristic features. None of them has been fully studied yet, despite the fact that research is ongoing. The hydrosphere, the water shell of the planet, is of great interest both to scientists and to simply curious people who want to study the processes taking place on Earth in more depth.
Water is the basis of all life, it is a powerful vehicle, an excellent solvent and a truly endless pantry of food and mineral resources.
What is the hydrosphere made of?
The hydrosphere includes all water that is not chemically bound and regardless of the state of aggregation (liquid, vapor, frozen) it is in. The general view of the classification of parts of the hydrosphere looks like this:
World Ocean
This is the main, most significant part of the hydrosphere. The totality of the oceans is a water shell that is not continuous. It is divided by islands and continents. The waters of the World Ocean are characterized by a common salt composition. It includes four main oceans - the Pacific, Atlantic, Arctic and Indian oceans. Some sources also distinguish the fifth, the Southern Ocean.
The study of the oceans began many centuries ago. The first explorers are navigators - James Cook and Ferdinand Magellan. It was thanks to these travelers that European scientists received invaluable information about the extent of the water area and the outlines and sizes of the continents.
The oceanosphere makes up about 96% of the world's oceans and has a fairly uniform salt composition. Fresh water also enters the oceans, but their share is small - only about half a million cubic kilometers. These waters enter the oceans with precipitation and river runoff. A small amount of incoming fresh water determines the constancy of the composition of salt in ocean waters.
continental waters
Continental waters (also called surface waters) are those that are temporarily or permanently located in water bodies located on the surface of the globe. These include all water flowing and collecting on the surface of the earth:
- swamps;
- rivers;
- seas;
- other drains and reservoirs (for example, reservoirs).
Surface waters are divided into fresh and saline, and are the opposite of groundwater.
The groundwater
All waters located in the earth's crust (in rocks) are called. They can be in gaseous, solid or liquid state. Groundwater makes up a significant part of the planet's water reserves. Their total is 60 million cubic kilometers. Groundwater is classified according to its depth. They are:
- mineral
- artesian
- ground
- interstratal
- soil
Mineral waters are waters containing in their, trace elements, dissolved salt.
Artesian - this is pressure groundwater, located between water-resistant layers in rocks. They belong to minerals, and usually lie at a depth of 100 meters to one kilometer.
Groundwater is called gravitational water, located in the upper, closest to the surface, water-resistant layer. This type of groundwater has a free surface and usually does not have a solid rock roof.
Interstratal waters are called low-lying waters located between layers.
Soil waters are waters that move under the influence of molecular forces or gravity and fill some of the gaps between the particles of the soil cover.
General properties of the components of the hydrosphere
Despite the variety of conditions, compositions and locations, the hydrosphere of our planet is one. It unites all the waters of the globe with a common source of origin (the earth's mantle) and the interconnection of all the waters included in the water cycle on the planet.
The water cycle is an ongoing process, consisting in constant movement under the influence of gravity and solar energy. The water cycle is a link for the entire shell of the Earth, but also connects other shells - the atmosphere, biosphere and lithosphere.
During this process, it can be in the main three states. Throughout the existence of the hydrosphere, it is being updated, and each of its parts is updated over a different period of time. Thus, the period of renewal of the waters of the World Ocean is approximately three thousand years, the water vapor in the atmosphere is completely renewed in eight days, and the cover glaciers of Antarctica may take up to ten million years to renew. An interesting fact: all waters that are in a solid state (in permafrost, glaciers, snow covers) are united by the name cryosphere.
The hydrosphere includes atmospheric, surface and ground water. Each of these groups is divided into subgroups. The quantitative ratio of the types of hydrosphere waters is given in Table 1 and Figure 2.
Table 1. Parts of the hydrosphere
Rice. 2. Quantitative ratio of parts of the hydrosphere
Fresh water, occupying only a small percentage of the total composition of the planet's hydrosphere, plays an important role in human life.
About 75% of all fresh water on Earth is contained in the glaciers of the polar zones, in snow and permafrost. This water comes together under the name cryosphere. If all the ice in the cryosphere melted, the ocean level would rise by 64 meters. Recently, scientists have been anxiously monitoring the Arctic and Antarctic ice shelves. In the last few years alone, two glaciers have collapsed that have remained motionless for the past ten thousand years. Read more about it here...
20% of all fresh water reserves are groundwater and amount to 85 thousand km³.
The share of rivers, lakes, swamps and other freshwater reservoirs accounts for only 1% of fresh water. But due to the renewability of water resources, this is enough to supply water to the entire planet.
Rivers at a certain point in time contain only 1.2 thousand km 3, however, the annual flow of water for the entire planet is 41.8 thousand km 3. The lakes contain 280 thousand km 3 of water.
Up to 14 thousand km³ of water is in the atmosphere vapor, but during the year the moisture in the atmosphere is replaced up to 40 times and up to 520 thousand km 3 of water falls on the earth's surface in the form of precipitation. Precipitation is the main source of surface water renewal.
In general, the division of the hydrosphere into the World Ocean, continental waters and groundwaters is accepted. Most of the water is concentrated in the ocean, much less - in the continental river network and groundwater. There are also large reserves of water in the atmosphere, in the form of clouds and water vapor.
Over 96% of the volume of the hydrosphere is seas and oceans, about 2% is groundwater, about 2% is ice and snow, and about 0.02% is land surface water. Part of the water is in a solid state in the form of glaciers, snow cover and permafrost, representing the cryosphere.
Thus, the upper boundary of the hydrosphere reaches heights of 700-800 km, and the lower one - depths - 700-800 km from the Earth's surface. The lower boundary of the hydrosphere is assumed to be at the level of the mantle surface (the Mohorovichic surface), while the upper boundary lies in the upper layers of the atmosphere.
World water cycle- this is a process of continuous movement of water under the influence of solar energy and gravity, covering the hydrosphere, atmosphere, lithosphere and living organisms. From the earth's surface, under the influence of solar heat, water evaporates, and most of it (about 86%) evaporates from the surface of the oceans. Once in the atmosphere, water vapor condenses during cooling, and under the influence of gravity, the water returns to the earth's surface in the form of precipitation. A significant amount of precipitation falls back into the ocean.
The water cycle, in which only the ocean and atmosphere take part, is called small, or oceanic, the water cycle. The land is involved in the global, or large, water cycle: the evaporation of water from the surface of the ocean and land, the transfer of water vapor from the ocean to land, the condensation of vapor, the formation of clouds and precipitation on the surface of the ocean and land. Next is the surface and underground runoff of land waters into the ocean. Thus, the water cycle, in which, in addition to the ocean and the atmosphere, land also takes part, is called the global water cycle.
The annual amount of precipitation falling on the earth's surface is equal to the amount of water evaporated in total from the surface of the land and oceans. P + R + T - E - F = N (N>0) General water balance equation, where E - evaporation, P - precipitation, R - regional, underground and other types of runoff controlled by precipitation, T - endogenous inputs water, F - loss on photolysis.
The world ocean occupies 70.8% of the earth's surface. Its average depth is 3.8 km, the average water temperature is 3.8°C. The share of the World Ocean accounts for about 90% of all waters of the hydrosphere, therefore, chem. the composition of the latter is close to the composition of ocean waters, in which O (85.7%), H (10.8%), C1 (1.93%) and Na (1.03%) predominate. Most of all in the World Ocean (and in G.) contains ions Cl - , SO 2 2- , Na + , Mg 2+ , somewhat less - Br - , Ca 2+ , K + . A river is a constant stream of water flowing in a channel developed by him and fed mainly by precipitation.
Parts of the river: source- the place where the river originates. The source can be a spring, a lake, a swamp, a glacier in the mountains; mouth A place where a river flows into a sea, lake or other river. A depression in relief that extends from the source to the mouth of a river river valley. The depression in which the river constantly flows is the channel. floodplain- flat, flooded during the flood bottom of the river valley.
Above the floodplain, the slopes of the valley usually rise, often in a stepped form. These steps are called terraces. They arise as a result of the eroding activity of the river (erosion), caused by a decrease in the erosion base.
river system a river with all its tributaries. The name of the system is given by the name of the main river. river basin- the area from which the river with all its tributaries collects water. Watershed- a line dividing the basins of two rivers or oceans. Usually some elevated spaces serve as watersheds. Depending on the nutrition, rivers are distinguished with rain, snow, glacial, underground, and when they are combined, with mixed nutrition. The regime of the river largely depends on what kind of nutrition prevails.
River regime- regular changes in the state of rivers over time, due to the physical and geographical properties of the basin and, first of all, climatic conditions. The river regime manifests itself in the form of daily, seasonal and long-term fluctuations in the level and flow of water, ice phenomena, water temperature, the amount of sediment carried by the flow, etc. The elements of the river regime are, for example, low water - the water level in the river in the season of its lowest standing and high water - a prolonged rise in water in the river, caused by the main source of food, repeated from year to year. Depending on the presence of hydraulic structures on rivers (for example, hydroelectric power stations) that affect the regime of the river, there are regulated and natural regimes of rivers. All the rivers of the globe are distributed among the basins of the four oceans. Lakes are reservoirs of slow water exchange located in natural depressions on the land surface.
By origin, lake basins can be: 1) tectonic(formed in faults in the earth's crust, usually deep, and have banks with steep slopes); 2) volcanic(in the craters of extinct volcanoes); 3) glacial(characteristic of territories subjected to glaciation); four) karst(characteristic for areas of distribution of soluble rocks - gypsum, chalk, limestone, appear in places of failures when rocks are dissolved by groundwater); 5) dammed(they are also called dams; they arise as a result of blocking the riverbed with blocks of rocks during landslides in the mountains); 6) oxbow lakes(a lake on a floodplain or a lower terrace above a floodplain is a section of a river separated from the main channel); 7) artificial(reservoirs, ponds). Lakes are fed by atmospheric precipitation, groundwater and surface water flowing into them.
According to the water regime, they distinguish sewage and drainless lakes.
Depending on the degree of salinity of the water, the lakes are insipid and salty.
According to the origin of the water mass, lakes are of two types: 1) lakes, the water mass of which is of atmospheric origin (such lakes prevail in number); 2) relic, or residual, - were once part of the World Ocean (Caspian Lake, etc.) Swamps - excessively moistened land areas covered with moisture-loving vegetation and having a peat layer of at least 0.3 m. The water in the swamps is in a bound state . Marshes are formed due to the overgrowth of lakes and the swamping of land. Lowland swamps are fed by ground or river waters, relatively rich in salts. riding swamps are fed directly by atmospheric precipitation. They are located in watersheds. The main reason for the formation of huge swamps is the excessive humidity of the climate, combined with a high level of groundwater due to the close occurrence of water-resistant rocks and flat relief to the surface.
Glaciers- Atmospheric water turned into ice. Glaciers are constantly moving due to their plasticity. Under the influence of gravity, the speed of their movement reaches several hundred meters per year. The movement slows down or accelerates depending on the amount of precipitation, warming or cooling of the climate, and in the mountains, the movement of glaciers is influenced by tectonic uplifts. Permafrost. By permafrost, or permafrost, one should understand the strata of frozen rocks that do not thaw for a long time - from several years to tens and hundreds of thousands of years. Water in permafrost is in a solid state, in the form of ice cement. The emergence of permafrost occurs in conditions of very low winter temperatures and low snow cover.
Including the total mass of water found on, under and above the surface of the planet. Water in the hydrosphere can be in three states of aggregation: liquid (water), solid (ice) and gaseous (water vapor). The Earth's hydrosphere, unique in the solar system, plays one of the primary roles in sustaining life on our planet.
Total volume of hydrosphere waters
The earth has an area of about 510,066,000 km²; almost 71% of the planet's surface is covered with salt water with a volume of about 1.4 billion km³ and an average temperature of about 4°C, not much above the freezing point of water. It contains almost 94% of the volume of all water on Earth. The remainder occurs as fresh water, three-quarters of which is locked up as ice in the polar regions. Most of the remaining fresh water is groundwater contained in soils and rocks; and less than 1% is found in the world's lakes and rivers. As a percentage, atmospheric water vapor is negligible, but the transfer of water evaporated from the oceans to the land surface is an integral part of the hydrological cycle that renews and sustains life on the planet.
Hydrosphere objects
Scheme of the main components of the hydrosphere of the planet Earth
The objects of the hydrosphere are all liquid and frozen surface water, groundwater in soil and rocks, as well as water vapor. The entire hydrosphere of the Earth, as shown in the diagram above, can be divided into the following large objects or parts:
- World Ocean: contains 1.37 billion km³ or 93.96% of the volume of the entire hydrosphere;
- The groundwater: contain 64 million km³ or 4.38% of the volume of the entire hydrosphere;
- Glaciers: contain 24 million km³ or 1.65% of the volume of the entire hydrosphere;
- Lakes and reservoirs: contain 280 thousand km³ or 0.02% of the volume of the entire hydrosphere;
- Soils: contain 85 thousand km³ or 0.01% of the volume of the entire hydrosphere;
- Atmospheric steam: contains 14 thousand km³ or 0.001% of the volume of the entire hydrosphere;
- Rivers: contain a little more than 1 thousand km³ or 0.0001% of the volume of the entire hydrosphere;
- TOTAL VOLUME OF THE EARTH'S HYDROSPHERE: about 1.458 billion km³.
The water cycle in nature
Scheme of the cycle of nature
Involves the movement of water from the oceans through the atmosphere to the continents and then back to the oceans above, on and below the land surface. The cycle includes processes such as sedimentation, evaporation, transpiration, infiltration, percolation and runoff. These processes operate throughout the hydrosphere, which extends about 15 km into the atmosphere and up to about 5 km deep into the earth's crust.
About a third of the solar energy that reaches the Earth's surface is used to evaporate ocean water. The resulting atmospheric moisture condenses into clouds, rain, snow and dew. Humidity is a decisive factor in determining the weather. It is the driving force behind storms and is responsible for the separation of electrical charge, which is what causes lightning and therefore the natural ones that negatively affect some. Precipitation moistens the soil, replenishes underground aquifers, destroys the landscape, nourishes living organisms, and fills rivers that carry dissolved chemicals and sediment back to the oceans.
Importance of the hydrosphere
Water plays an important role in the carbon cycle. Under the influence of water and dissolved carbon dioxide, calcium is weathered from continental rocks and transported to the oceans, where calcium carbonate is formed (including the shells of marine organisms). Eventually the carbonates are deposited on the seabed and lithified to form limestones. Some of these carbonate rocks later sink into the interior of the Earth due to the global process of plate tectonics and melt, which leads to the release of carbon dioxide (for example, from volcanoes) into the atmosphere. The hydrological cycle, the circulation of carbon and oxygen through the geological and biological systems of the Earth, is the basis for maintaining the life of the planet, the formation of erosion and weathering of the continents, and they contrast sharply with the absence of such processes, for example, on Venus.
Problems of the hydrosphere
The process of melting glaciers
There are many problems that are directly related to the hydrosphere, but the most global are the following:
sea level rise
Sea level rise is an emerging issue that could affect many people and ecosystems around the world. Tide level measurements show a worldwide increase in sea level of 15-20 cm, and the IPCC (Intergovernmental Panel on Climate Change) has suggested that the increase is due to the expansion of ocean water due to rising ambient temperatures, melting mountain glaciers, and ice caps. Most of the Earth's glaciers are melting due to, and many scientific studies have shown that the rate of this process is increasing, and also has a significant impact on global sea levels.
Reduction of Arctic sea ice
Over the past few decades, Arctic sea ice has shrunk significantly. Recent NASA studies show that it is declining at a rate of 9.6% per decade. Such thinning and removal of ice affects the balance of heat and animals. For example, populations are declining due to a break in the ice that separates them from land, and many individuals drown in attempts to swim across. This loss of sea ice also affects the albedo, or reflectivity of the Earth's surface, causing the dark oceans to absorb more heat.
Precipitation change
An increase in precipitation can lead to floods and landslides, while a decrease can lead to droughts and fires. El Niño events, monsoons and hurricanes also affect short-term global climate change. For example, a change in ocean currents off the coast of Peru associated with an El Niño event could lead to changes in weather conditions throughout North America. Changes in monsoon patterns due to rising temperatures can cause droughts in areas around the world that depend on seasonal winds. Hurricanes that intensify with rising sea surface temperatures will become more destructive to humans in the future.
Melting permafrost
It melts as the global temperature rises. This affects the people living in this area the most, as the soil on which the houses are located becomes unstable. Not only is there an immediate effect, but scientists fear that thawing permafrost will release huge amounts of carbon dioxide (CO2) and methane (CH4) into the atmosphere, greatly impacting the environment in the long term. The released will contribute to further global warming by releasing heat into the atmosphere.
Anthropogenic influence of man on the hydrosphere
Humans have had a significant impact on our planet's hydrosphere, and this will continue as the world's population and human needs increase. Global climate change, river flooding, wetland drainage, flow reduction, and irrigation have put pressure on existing freshwater hydrosphere systems. The steady state is being disturbed by the release of toxic chemicals, radioactive substances and other industrial wastes, as well as the leakage of mineral fertilizers, herbicides and pesticides into the Earth's water sources.
Acid rain, caused by the release of sulfur dioxide and nitrogen oxides from the burning of fossil fuels, has become a worldwide problem. The acidification of freshwater lakes and the increased concentration of aluminum in their waters are believed to be responsible for significant changes in lake ecosystems. In particular, many lakes today do not have significant fish populations.
Eutrophication caused by human intervention is becoming a problem for freshwater ecosystems. As excess nutrients and organic matter from agricultural and industrial wastewater are released into water systems, they become artificially enriched. This affects coastal marine ecosystems as well as the introduction of organic matter into the oceans, which is many times greater than in pre-human times. This has caused biotic changes in some areas, such as the North Sea, where cyanobacteria thrive and diatoms thrive.
As the population increases, the need for drinking water will also increase, and in many parts of the world, due to temperature changes, fresh water is extremely difficult to obtain. As people irresponsibly divert rivers and deplete natural water supplies, this creates even more problems.
Humans have had a great impact on the hydrosphere and will continue to do so in the future. It is important to understand the impact we have on the environment and work to reduce negative impacts.
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