The science of natural processes in the oceans. Physical and geographical science. Examples of physical geography. Geography as a science
Ministry of Science and Education of Ukraine
Taurida National University
Them. V.I.Vernadsky
Faculty of Geography
Department of Physical Geography and Oceanology
Yu.F. BEZRUKOV
OCEANOLOGY
Physical phenomena and processes in the ocean
Simferopol 2006
Foreword
Introduction
1. Subject and tasks of oceanology
2. Major Oceanological Organizations
2.1. International organizations
2.2. Important National Scientific Institutions
3. History of the study of the oceans
4. Geographical characteristics of the oceans
4.1. Morphometric characteristics and division of the World Ocean
4.2. The world ocean as a single natural object
4.3. Geographical characteristics of the oceans
4.4. The structure of the oceanic crust and the main elements of the bottom topography
5. Structure and chemical composition of sea water
5.1. The molecular structure of water and its anomalies
5.2. The chemical composition of sea water
5.3. Salinity of sea water
5.4. Dissolved gases
6. Main physical characteristics of sea water
6.1. Density, specific gravity and specific volume.
Equation of state of sea water
6.2. Pressure and compressibility of sea water
6.3. Thermal properties of sea water
6.4. Diffusion and osmosis
7. Turbulent mixing in the ocean
7.1. Types of turbulent mixing
7.2. Viscosity (or force of internal friction)
7.3. Marine turbulence
7.4. Elements of the statistical theory of turbulence
7.5. Turbulent exchange in the ocean
7.6. Stability of layers in the sea
7.7. convective mixing
8. Optical properties of sea water
8.1. light emission
8.2. Radiation balance of the Earth and illumination of the sea surface
8.3. Absorption and scattering of light in the sea
8.4. Transparency and color of water
8.4. Bioluminescence and sea bloom
9. Acoustic properties of sea water
9.1. Sound propagation speed
9.2. Absorption and scattering of sound in the sea. Reverberation
9.3. refraction of sound rays. Underwater sound channel
9.4. Biohydroacoustics
10. Ocean-atmosphere interaction
10.1. The relationship of processes in the ocean and atmosphere
10.2. Process variability in the ocean
10.3. Heat transfer in the ocean-atmosphere system
10.3.1. Components of the heat balance of the ocean
10.4. Moisture exchange in the ocean-atmosphere system
10.5. El Niño and La Niña
10.6. Global warming: reality and forecast
11. Distribution of temperature and salinity
In the oceans
11.1. Temperature distribution
11.2. Salinity distribution
12. Thermohaline analysis of ocean waters
12.1. T, S-curves
12.2. Mixing of two and three water masses
12.3. Mixing of four water masses
12.4. Analytic geometry of T,S-curves
12.5. Statistical T,S-analysis
13. Water masses of the oceans
14. Frontal zones and fronts in the World Ocean
15. Physical-geographical zoning of the World Ocean
16. Sea ice
16.1. Ice classification
16.2. Salinity of ice
16.3. Physical properties of ice
16.4. Mechanical properties of ice
16.5. ice drift
16.6. Distribution of ice in the oceans
17. The biological structure of the ocean
17.1. Biological zones and provinces in the ocean
17.2. marine hydrobionts
17.3. marine ecosystem
17.4. Sea fishing
18. Natural resources of the oceans
English system of measures
Even primitive people began to accumulate knowledge about what surrounds them. As mankind developed, this knowledge became more and more. People sought to know the world around them as deeply as possible. Gradually, various sciences arose and began to develop. Some of them explore nature, others - the life of people, their spiritual world, history, culture, economy.
Nature in the old days was called "nature". Therefore, the sciences of nature received the general name natural sciences. They study various bodies, substances and natural phenomena. The body can be called any object, any living being. Substances are what bodies are made of. And phenomena, as you already know, are any changes that occur in nature.
Let's get acquainted with the basic sciences about nature.
Astronomy
The name of this science comes from the Greek words "astron" - "star", "nomos" - "law".
Astronomy is the science of celestial bodies: their origin, structure, composition, movement in outer space.
The world of celestial bodies, perhaps, seems to us a particularly mysterious part of nature. And probably, everyone, more than once peering into the distant, bewitching starry sky, felt that all people and the whole Earth were a small part of a huge, immense world - the Universe. Astronomy has already uncovered many of the mysteries of the universe and continues to solve them, striking the imagination of people with new discoveries.
Physics
Translated from Greek, the word "physis" means. tea "nature".
Physics is a science that studies various natural phenomena.
We often encounter many of these phenomena in everyday life. For example, the movement of bodies, the changes that occur to bodies when heated and cooled, electricity, sound, light. It is physics that answers the questions why lightning flashes and thunder rumbles, how an echo occurs, what a rainbow is ... But physics does not only explain what can be seen in nature. It is the basis of technology. Without knowledge of physics, it is impossible to create a car, or an airplane, or a refrigerator, or a crane, or a computer. It is hard to even imagine what our life would be like if the science of physics did not exist.
Chemistry
The origin of the name of this science is not exactly known, perhaps from the Greek word "chemeusis" - "mixing".
Chemistry is the science of substances and their transformations.
You already know that bodies are made of substances. Water, oxygen, carbon dioxide, sugar, starch, table salt are all examples of substances. There are a lot of them now - several million. Each substance has its own properties. Under certain conditions, some substances may produce others. There is no miracle, no magic in such transformations. Thanks to chemistry, people have learned to obtain in laboratories and chemical plants those substances that are needed in the economy and in everyday life.
Geography
This is another earth science. Its name comes from the Greek words "geo" - "earth", "grafo" - "I write", i.e. "description of the earth".
Indeed, geography describes our planet: what oceans and continents it has, seas, lakes and rivers, lowlands, hills and mountains, what countries, cities and villages arose on Earth, what is the life and economy of the peoples inhabiting our planet. A lot of questions are studied by geography. As you can see, they concern not only nature, but also life and economic activities of people. About what main sections geography is divided into and what they study, as well as what geographical sciences exist, you will learn from the next paragraph.
Biology
Translated from Greek, the word "bios" means "life", "logos" - "science, teaching".
Biology is the science of living nature.
Without life, it is impossible to imagine our planet. A variety of creatures - bacteria, protozoa, fungi, plants, animals - inhabited the oceans and land, plains and mountains, soil and even deep, mysterious caves. We ourselves are part of nature. Biology answers many questions: what living beings are there on Earth and how many there are, how a living body is arranged and works, how organisms reproduce and develop, how they are connected with each other and with inanimate nature.
Ecology
The name of this science comes from the Greek words "ekos" - "house", "logos" - "science, teaching".
Ecology is the science of the relationship of organisms with each other and with their environment, the interaction of man and nature.
Ecology originated as a part of biology, but now more and more people talk about it as an independent science - the science of the natural home of mankind. The word "ecology" is often heard on radio, television, and appears in newspapers. This is due to the fact that our natural home is in danger. To save it, each person should be at least a little familiar with the environment.
People have always sought to know the world around them. Gradually, various sciences arose and began to develop. The sciences of nature are called natural sciences. They study various bodies, substances and natural phenomena. The basic sciences of nature include astronomy, physics, chemistry, geography, biology, geology, and ecology. Astronomy is the science of the heavenly bodies. Physics considers various natural phenomena. Chemistry is the science of substances and their transformations. Geography studies our planet. Biology is the science of living nature. Ecology is the science of the relationship of organisms with each other and with their environment, the interaction of man and nature.
- What is the common name for the natural sciences?
- What are bodies, substances and phenomena of nature? Give examples of bodies and substances that you encounter in everyday life.
- List the natural sciences you know.
- What does each of the natural sciences (astronomy, physics, chemistry, geography, biology, ecology) study?
- The great English scientist Isaac Newton wrote: “I don’t know about others, but I feel like a child who wanders all day at the water’s edge, finding either a shell or a stone polished by a wave, while a huge ocean of truth stretches before him, boundless, unexplored.” How do you explain these words?
Site search.
The World Ocean, covering 71% of the Earth's surface, strikes with the complexity and variety of processes developing in it.
From the surface to the greatest depths, the waters of the ocean are in continuous motion. These complex movements of water from huge ocean currents to the smallest eddies are excited by tide-forming forces and serve as a manifestation of the interaction of the atmosphere and the ocean.
The water mass of the ocean at low latitudes accumulates heat received from the sun and transfers this heat to high latitudes. The redistribution of heat, in turn, excites certain atmospheric processes. So, in the area of convergence of cold and warm currents in the North Atlantic, powerful cyclones arise. They reach Europe and often determine the weather throughout its space up to the Urals.
The living matter of the ocean is very unevenly distributed over the depths. In different regions of the ocean, biomass depends on climatic conditions and the supply of nitrogen and phosphorus salts to surface waters. The ocean is home to a great variety of plants and animals. From bacteria and unicellular green phytoplankton algae to the largest mammals on earth - whales, whose weight reaches 150 tons. All living organisms form a single biological system with their own laws of existence and evolution.
Loose sediments accumulate very slowly at the bottom of the ocean. This is the first stage in the formation of sedimentary rocks. In order for geologists working on land to be able to correctly decipher the geological history of a particular territory, it is necessary to study in detail the modern processes of sedimentation.
As it turned out in recent decades, the earth's crust under the ocean has great mobility. At the bottom of the ocean, mountain ranges, deep rift valleys, and volcanic cones are formed. In a word, the bottom of the ocean "lives" violently, and often there are such strong earthquakes that huge devastating tsunami waves rapidly run across the surface of the ocean.
Trying to explore the nature of the ocean - this grandiose sphere of the earth, scientists are faced with certain difficulties, to overcome which they have to apply the methods of all the main natural sciences: physics, chemistry, mathematics, biology, geology. Oceanology is usually spoken of as a union of various sciences, a federation of sciences united by the subject of study. In this approach to the study of the nature of the ocean, there is a natural desire to penetrate deeper into its secrets and an urgent need to deeply and comprehensively know the characteristic features of its nature.
These tasks are very complex, and they have to be solved by a large team of scientists and specialists. In order to imagine exactly how this is done, consider the three most relevant areas of ocean science:
- ocean-atmosphere interaction;
- the biological structure of the ocean;
- ocean floor geology and its mineral resources.
The long-term tireless work of the oldest Soviet research vessel "Vityaz" has completed. It arrived at the Kaliningrad sea port. The 65th farewell flight, which lasted more than two months, has ended.
Here is the last "traveling" entry in the ship's log of a veteran of our oceanographic fleet, who, in thirty years of voyages, left more than a million miles behind the stern.
In a conversation with a Pravda correspondent, the head of the expedition, Professor A. A. Aksenov, noted that the 65th flight of the Vityaz, like all previous ones, was successful. During complex research in the deep-sea regions of the Mediterranean Sea and the Atlantic Ocean, new scientific data have been obtained that will enrich our knowledge of the life of the sea.
Vityaz will be temporarily based in Kaliningrad. It is assumed that then it will become the base for the creation of the Museum of the World Ocean.
For several years, scientists from many countries have been working on the international project GAAP (Global Atmospheric Process Research Program). The aim of this work is to find a reliable method for weather forecasting. There is no need to explain how important this is. It will be possible to know in advance about drought, floods, downpours, strong winds, heat and cold ...
So far, no one can give such a forecast. What is the main difficulty? It is impossible to accurately describe the processes of interaction between the ocean and the atmosphere with mathematical equations.
Nearly all of the water that falls on land as rain and rain enters the atmosphere from the surface of the ocean. Ocean waters in the tropics become very hot, and currents carry this heat to high latitudes. Over the ocean there are huge whirlwinds - cyclones that determine the weather on land.
The ocean is the kitchen of the weather... But there are very few permanent weather stations in the ocean. These are a few islands and several automatic floating stations.
Scientists are trying to build a mathematical model of the interaction between the ocean and the atmosphere, but it must be real and accurate, and this lacks many data on the state of the atmosphere over the ocean.
The solution was found to be very accurate and continuous measurements from ships, aircraft and meteorological satellites in a small area of the ocean. Such an international experiment called "Tropex" was carried out in the tropical zone of the Atlantic Ocean in 1974, and very important data were obtained for building a mathematical model.
It is necessary to know the whole system of currents in the ocean. Currents carry heat (and cold), nutritious mineral salts necessary for the development of life. A long time ago, sailors began to collect information about the currents. It began in the 15th-16th centuries, when sailing ships took to the open ocean. Nowadays, all sailors know that there are detailed maps of surface currents, and use them. However, in the last 20-30 years, discoveries have been made that have shown how inaccurate current maps are and how complex the overall picture of ocean circulation is.
In the equatorial zone of the Pacific and Atlantic oceans, powerful deep currents were explored, measured and mapped. They are known as the Cromwell Current in the Pacific and the Lomonosov Current in the Atlantic Ocean.
In the west of the Atlantic Ocean, the deep Antilo-Guiana countercurrent was discovered. And under the famous Gulf Stream turned out to be the Counter-Gulf Stream.
In 1970, Soviet scientists conducted a very interesting study. A series of buoy stations have been installed in the tropical zone of the Atlantic Ocean. Currents at various depths were continuously recorded at each station. The measurements lasted half a year, and hydrological surveys were periodically performed in the area of measurements to obtain data on the general pattern of water movement. After processing and summarizing the measurement materials, a very important general pattern emerged. It turns out that the previously existing idea of a relatively uniform nature of the constant trade wind current, which is excited by the north trade winds, does not correspond to reality. There is no such stream, this huge river in liquid banks.
Huge whirlpools, whirlpools, tens and even hundreds of kilometers in size, move in the zone of the trade wind current. The center of such a vortex moves at a speed of about 10 cm/s, but on the periphery of the vortex, the flow velocity is much higher. This discovery of Soviet scientists was later confirmed by American researchers, and in 1973 similar eddies were traced in Soviet expeditions operating in the North Pacific.
In 1977-1978. A special experiment was set up to study the eddy structure of currents in the area of the Sargasso Sea in the west of the North Atlantic. Over a large area, Soviet and American expeditions continuously measured currents for 15 months. This huge amount of material has not yet been fully analyzed, but the formulation of the problem itself required massive specially designed measurements.
Particular attention to the so-called synoptic eddies in the ocean is due to the fact that it is the eddies that carry the largest share of the current energy. Consequently, their careful study can bring scientists much closer to solving the problem of long-range weather forecasting.
Another most interesting phenomenon associated with ocean currents has been discovered in recent years. To the east and west of the powerful Gulf Stream, very stable so-called rings (rings) were found. Like a river, the Gulf Stream has strong meanders. In some places, the meanders close, and a ring is formed, in which the temperature of the hearth differs sharply at the periphery and in the center. Such rings have also been traced on the periphery of the powerful Kuroshio current in the northwestern part of the Pacific Ocean. Special observations of rings in the Atlantic and Pacific oceans have shown that these formations are very stable, maintaining a significant difference in water temperature on the periphery and inside the ring for 2-3 years.
In 1969, for the first time, special probes were used to continuously measure temperature and salinity at various depths. Prior to this, the temperature was measured with mercury thermometers at several points at different depths, and water was raised from the same depths in bottles. Then the salinity of the water was determined and the salinity and temperature values were plotted on a graph. The depth distribution of these water properties was obtained. Measurements at individual points (discrete) did not even allow us to assume that the water temperature changes with depth as complexly as it was shown by continuous measurements with the probe.
It turned out that the entire water mass from the surface to great depths is divided into thin layers. The difference in temperature between adjacent horizontal layers reaches several tenths of a degree. These layers, from several centimeters to several meters thick, sometimes exist for several hours, sometimes disappear in a few minutes.
The first measurements, made in 1969, seemed to many to be a random phenomenon in the ocean. It cannot be, the skeptics said, that the mighty ocean waves and currents do not mix the water. But in subsequent years, when the sounding of the water column with precision instruments was carried out throughout the ocean, it turned out that the thin-layered structure of the water column was found everywhere and always. The reasons for this phenomenon are not entirely clear. So far, they explain it this way: for one reason or another, numerous fairly clear boundaries appear in the water column, separating layers with different densities. At the boundary of two layers of different density, internal waves very easily arise, which mix the water. In the process of destruction of internal waves, new homogeneous layers arise, and the boundaries of the layers are formed at different depths. So this process is repeated many times, the depth and thickness of layers with sharp boundaries change, but the general nature of the water column remains unchanged.
In 1979, the pilot phase of the International Program for the Study of Global Atmospheric Processes (PGAP) began. Several dozen ships, automatic observation stations in the ocean, special aircraft and meteorological satellites, all this mass of research facilities is working throughout the entire space of the World Ocean. All participants in this experiment work according to a single coordinated program so that, by comparing the materials of the international experiment, it would be possible to build a global model of the state of the atmosphere and ocean.
If we take into account that in addition to the general task - the search for a reliable method of long-term weather forecasting, it is necessary to know a lot of particular facts, then the general task of ocean physics will seem very, very complicated: measurement methods, instruments, the operation of which is based on the use of the most modern electronic circuits, are quite difficult processing of the information received with the obligatory use of a computer; construction of very complex and original mathematical models of processes developing in the water column of the ocean and at the boundary with the atmosphere; setting up extensive experiments in characteristic regions of the ocean. These are the general features of modern research in the field of ocean physics.
Special difficulties arise in the study of living matter in the ocean. Relatively recently, the necessary materials were obtained for a general characterization of the biological structure of the ocean.
Only in 1949 was life discovered at depths of more than 6000 m. Later, the deep-sea fauna - the fauna of the ultraabyssal - turned out to be the most interesting object of special research. At such depths, the conditions of existence are very stable on a geological time scale. Based on the similarity of the ultra-abyssal fauna, it is possible to establish the former connections of individual oceanic depressions and restore the geographical conditions of the geological past. So, for example, comparing the deep-sea fauna of the Caribbean Sea and the Eastern Pacific Ocean, scientists have found that in the geological past there was no Isthmus of Panama.
Somewhat later, a striking discovery was made - a new type of animal, pogonophores, was discovered in the ocean. A thorough study of their anatomy, a systematic classification made up the content of one of the outstanding works in modern biology - A. V. Ivanov's monograph "Pogonophores". These two examples show how difficult it turned out to be to study the distribution of life in the ocean, and even more so the general laws governing the functioning of biological systems in the ocean.
Comparing disparate facts, comparing the biology of the main groups of plants and animals, scientists have come to important conclusions. The total biological production of the World Ocean turned out to be somewhat less than a similar value characterizing the entire land area, despite the fact that the ocean area is 2.5 times larger than the land area. This is due to the fact that the areas of high biological productivity are the periphery of the ocean and the areas of deep water rise. The rest of the ocean is an almost lifeless desert, where only large predators can be found. Separate oases in the ocean desert are only small coral atolls.
Another important finding concerns the general characteristics of food chains in the ocean. The first link in the food chain is unicellular green algae phytoplankton. The next link is zooplankton, then planktivorous fish and predators. Milking animals - benthos, which are also food for fish, are of significant importance.
Reproduction in each link of the food price is such that the produced biomass is 10 times higher than its consumption. In other words, 90% of, for example, phytoplankton dies naturally and only 10% serves as food for zooplankton. It has also been established that zooplankton crustaceans perform vertical diurnal migrations in search of food. More recently, it was possible to detect clumps of bacteria in the diet of zooplankton crustaceans, and this type of food accounted for up to 30% of the total volume. The general result of modern studies of ocean biology is that an approach has been found and the first block mathematical model of the ecological system of the open ocean has been built. This is the first step towards the artificial regulation of ocean biological productivity.
What methods do biologists use in the ocean?
First of all, a variety of fishing gear. Small plankton organisms are caught with special cone nets. As a result of fishing, an average amount of plankton is obtained in weight units per unit volume of water. These nets can catch individual horizons of the water column or "filter" water from a given depth to the surface. Bottom animals are caught by various tools towed along the bottom. Fish and other nekton organisms are caught by mid-depth trawls.
Peculiar methods are used to study the food relationships of various plankton groups. Organisms “tag” with radioactive substances and then determine the amount and rate of grazing in the next link in the food chain.
In recent years, physical methods have been used to indirectly determine the amount of plankton in water. One of these methods is based on the use of a laser beam, which, as it were, probes the surface layer of water in the ocean and provides data on the total amount of phytoplankton. Another physical method is based on the use of the ability of plankton organisms to glow - bioluminescence. A special bathometer-probe is immersed in water, and as it sinks, the intensity of bioluminescence is recorded as an indicator of the amount of plankton. These methods very quickly and completely characterize the distribution of plankton in a variety of sounding points.
An important element in the study of the biological structure of the ocean is chemical research. The content of biogenic elements (mineral salts of nitrogen and phosphorus), dissolved oxygen, and a number of other important characteristics of the habitat of organisms are determined by chemical methods. Careful chemical determinations are especially important when studying highly productive coastal regions - upwelling zones. Here, with regular and strong winds from the shore, there is a strong collapse of water, accompanied by the rise of deep waters and their spread in the shallow area of the shelf. Deep waters contain in dissolved form a significant amount of mineral salts of nitrogen and phosphorus. As a result, phytoplankton flourishes in the upwelling zone and, ultimately, an area of commercial concentrations of fish is formed.
The prediction and registration of the specific nature of the habitat in the upwelling zone is carried out by chemical methods. Thus, in biology, the question of acceptable and applicable methods of research is being solved in our time in a complex way. While widely using traditional methods of biology, researchers are increasingly using the methods of physics and chemistry. The processing of materials, as well as their generalization in the form of optimized models, is carried out using the methods of modern mathematics.
In the field of ocean geology, so many new facts have been obtained over the past 30 years that many traditional ideas have had to be drastically changed.
Just 30 years ago, measuring the depth of the ocean floor was extremely difficult. It was necessary to lower a heavy lot with a load suspended on a long steel cable into the water. At the same time, the results were often erroneous, and the points with measured depths were separated from one another by hundreds of kilometers. Therefore, the idea of the vast expanses of the ocean floor as giant plains dominated.
In 1937, for the first time, a new method of measuring depths was applied, based on the effect of sound signal reflection from the bottom.
The principle of measuring depth with an echo sounder is very simple. A special vibrator mounted in the lower part of the ship's hull emits pulsating acoustic signals. The signals are reflected from the bottom surface and are picked up by the receiving device of the echo sounder. The round-trip time of the signal depends on the depth, and a continuous bottom profile is drawn on the tape as the ship moves. A series of such profiles, separated by relatively small distances, makes it possible to draw lines of equal depths - isobaths on the map and depict the bottom relief.
Depth measurements with an echo sounder have changed scientists' previous ideas about the topography of the ocean floor.
What does it look like?
A strip extending from the shore is called the continental shelf. Depths on the continental shelf usually do not exceed 200-300 m.
In the upper zone of the continental shelf there is a continuous and rapid transformation of the relief. The coast recedes under the onslaught of waves, and at the same time large accumulations of detrital material appear under the water. It is here that large deposits of sand, gravel, pebbles are formed - an excellent building material, crushed and sorted by nature itself. Various spits, embankments, bars, in turn, build up the coast in another place, separate lagoons, block river mouths.
In the tropical zone of the ocean, where the water is very clean and warm, grandiose coral structures grow - coastal and barrier reefs. They stretch for hundreds of kilometers. Coral reefs serve as a refuge for a great variety of organisms and together with them form a complex and extraordinary biological system. In a word, the upper zone of the shelf "lives" with a stormy geological life.
At depths of 100-200 m, geological processes seem to freeze. The relief becomes leveled, there are many bedrock outcrops at the bottom. The destruction of the rocks is very slow.
On the outer edge of the shelf, facing the ocean, the bottom surface slope becomes steeper. Sometimes slopes reach 40-50°. This is the continental slope. Its surface is cut by underwater canyons. Tense, sometimes catastrophic processes take place here. Silt accumulates on the slopes of underwater canyons. At times, the stability of the accumulations is suddenly broken, and a mud stream falls down along the bottom of the canyon.
The mud flow reaches the mouth of the canyon, and here the main mass of sand and large debris, being deposited, forms an alluvial cone - an underwater delta. A turbid flow goes beyond the continental foot. Quite often, separate alluvial fans unite, and a continuous strip of loose sediments of great thickness forms at the continental foot.
53% of the bottom area is occupied by the ocean bed, the area that until recently was considered a plain. In fact, the relief of the ocean floor is quite complex: uplifts of various structures and origins divide it into huge basins. The dimensions of oceanic basins can be estimated from at least one example: the northern and eastern basins of the Pacific Ocean cover an area larger than the entire North America.
A large area of the basins themselves is dominated by a hilly relief, sometimes there are separate seamounts. The height of the mountains of the ocean reaches 5-6 km, and their peaks often rise above the water.
In other areas, the ocean floor is crossed by huge gently sloping swells several hundred kilometers wide. Usually, volcanic islands are located on these shafts. In the Pacific Ocean, for example, there is the Hawaiian Wall, on which there is a chain of islands with active volcanoes and lava lakes.
Volcanic cones rise from the bottom of the ocean in many places. Sometimes the top of the volcano reaches the surface of the water, and then an island appears. Some of these islands are gradually being destroyed and hidden under water.
In the Pacific Ocean, several hundred volcanic cones have been discovered with clear traces of wave action on flat tops, submerged to a depth of 1000-1300 m.
The evolution of volcanoes may be different. Reef-forming corals settle at the top of the volcano. With slow sinking, corals build up a reef, and over time, a ring island is formed - an atoll with a lagoon in the middle. Coral reef growth can take a very long time. Drilling has been carried out on some Pacific atolls to determine the thickness of the coral limestone sequence. It turned out that it reaches 1500. This means that the top of the volcano descended slowly - for about 20 thousand years.
By studying the bottom topography and the geological structure of the ocean's solid crust, scientists have come to some new conclusions. The earth's crust under the ocean floor turned out to be much thinner than on the continents. On the continents, the thickness of the Earth's solid shell - the lithosphere - reaches 50-60 km, and in the ocean it does not exceed 5-7 km.
It also turned out that the lithosphere of land and ocean is different in rock composition. Under a layer of loose rocks - products of the destruction of the land surface lies a powerful granite layer, which is underlain by a basalt layer. There is no granite layer in the ocean, and loose deposits lie directly on the basalts.
Even more important was the discovery of a grandiose system of mountain ranges at the bottom of the ocean. The mountain system of mid-ocean ridges stretches across all the oceans for 80,000 km. In size, underwater ranges are comparable only to the greatest mountains on land, such as the Himalayas. The crests of underwater ridges are usually cut along by deep gorges, which were called rift valleys, or rifts. Their continuation can also be traced on land.
Scientists have realized that the global rift system is a very important phenomenon in the geological development of our entire planet. A period of careful study of the system of rift zones began, and soon such significant data were obtained that there was a sharp change in ideas about the geological history of the Earth.
Now scientists have again turned to the half-forgotten hypothesis of continental drift, expressed by the German scientist A. Wegener at the beginning of the century. A careful comparison of the contours of the continents separated by the Atlantic Ocean was made. At the same time, the geophysicist J. Bullard combined the contours of Europe and North America, Africa and South America not along the coastlines, but along the median line of the continental slope, approximately along the 1000 m isobath. The outlines of both ocean shores coincided so exactly that even inveterate skeptics could not doubt in the actual enormous horizontal movement of the continents.
Particularly convincing were the data obtained during geomagnetic surveys in the area of mid-ocean ridges. It turned out that the erupted basaltic lava gradually shifted to both sides of the crest of the ridge. Thus, direct evidence was obtained of the expansion of the oceans, the spreading of the earth's crust in the rift region and, in accordance with this, the drift of the continents.
Deep drilling in the ocean, which has been carried out for several years from the American ship Glomar Challenger, has again confirmed the fact of the expansion of the oceans. They even established the average value of the expansion of the Atlantic Ocean - a few centimeters per year.
It was also possible to explain the increased seismicity and volcanism at the periphery of the oceans.
All these new data formed the basis for the creation of a hypothesis (often called a theory, its arguments are so convincing) of tectonics (mobility) of lithospheric plates.
The original formulation of this theory belongs to the American scientists G. Hess and R. Dietz. Later it was developed and supplemented by Soviet, French and other scientists. The meaning of the new theory is reduced to the idea that the rigid shell of the Earth - the lithosphere - is divided into separate plates. These plates experience horizontal movements. The forces that set the lithospheric plates in motion are generated by convective currents, i.e., currents of the deep fiery-liquid substance of the Earth.
The spreading of plates to the sides is accompanied by the formation of mid-ocean ridges, on the crests of which gaping rift cracks appear. Through the rifts there is an outpouring of basaltic lava.
In other areas, lithospheric plates converge and collide. In these collisions, as a rule, a subduction of the edge of one plate under another is born. On the periphery of the oceans, such modern underthrust zones are known, where strong earthquakes often occur.
The theory of lithospheric plate tectonics is confirmed by many facts obtained over the past fifteen years in the ocean.
The general basis of modern ideas about the internal structure of the Earth and the processes occurring in its depths is the cosmogonic hypothesis of Academician O. Yu. Schmidt. According to him, the Earth, like other planets of the solar system, was formed by sticking together the cold matter of a dust cloud. Further growth of the Earth occurred by capturing new portions of the meteorite substance when passing through a dust cloud that once surrounded the Sun. As the planet grew, heavy (iron) meteorites sank and light (stone) meteorites emerged. This process (separation, differentiation) was so powerful that inside the planet the substance was melted and divided into a refractory (heavy) part and a fusible (lighter) part. At the same time, radioactive heating in the inner parts of the Earth also acted. All these processes led to the formation of a heavy inner core, a lighter outer core, lower and upper mantle. Geophysical data and calculations show that a huge energy is hidden in the bowels of the Earth, which is really capable of decisive transformations of the solid shell - the lithosphere.
Based on the cosmogonic hypothesis of O. 10. Schmidt, Academician A. P. Vinogradov developed a geochemical theory of the origin of the ocean. A.P. Vinogradov, through precise calculations, as well as experiments to study the differentiation of the molten substance of meteorites, established that the water mass of the ocean and the Earth's atmosphere was formed in the process of degassing of the substance of the upper mantle. This process continues to this day. In the upper mantle, indeed, a continuous differentiation of matter occurs, and its most fusible part penetrates the surface of the lithosphere in the form of basalt lava.
Ideas about the structure of the earth's crust and its dynamics are gradually being refined.
In 1973 and 1974 an unusual underwater expedition was carried out in the Atlantic Ocean. In a pre-selected area of the Mid-Atlantic Ridge, deep-sea dives of submersibles were carried out and a small but very important area of the ocean floor was studied in detail.
Exploring the bottom from surface vessels during the preparation of the expedition, the scientists studied the bottom topography in detail and discovered an area inside which there was a deep gorge, cutting along the crest of an underwater ridge - a rift valley. In the same area, there is a well-pronounced transform fault, which is transverse with respect to the crest of the ridge and the rift gorge.
Such a typical bottom structure - a rift gorge, a transform fault, young volcanoes - was surveyed from three submarines. The expedition was attended by the French bathyscaphe "Archimedes" with the special vessel "Marseille le Bian" providing its operation, the French submarine "Siana" with the vessel "Norua", the American research vessel "Knorr", the American submarine "Alvin" with the vessel "Lulu" .
A total of 51 deep dives were made over two seasons.
When performing deep-sea dives up to 3000 m, the crews of submarines encountered some difficulties.
The first thing that initially greatly complicated the research was the inability to determine the location of the underwater vehicle in conditions of a highly dissected terrain.
The underwater vehicle had to move, keeping a distance of no more than 5 m from the bottom. On steep slopes and crossing narrow valleys, the bathyscaphe and submarines could not use the system of acoustic beacons, as seamounts prevented the passage of signals. For this reason, an on-board system was put into operation on support vessels, with the help of which the exact location of the submarine was determined. From the support vessel, they monitored the underwater vehicle and directed its movement. Sometimes there was a direct danger to the underwater vehicle, and once such a situation arose.
On July 17, 1974, the Alvin submarine literally got stuck in a narrow crack and made attempts to get out of the trap for two and a half hours. The Alvin crew showed amazing resourcefulness and composure - after leaving the trap, they did not surface, but continued research for another two hours.
In addition to direct observations and measurements from underwater vehicles, when photographing and collecting samples, drilling was done in the expedition area from the famous special vessel "Glomar Challenger".
Finally, geophysical measurements were regularly carried out on board the Knorr research vessel, supplementing the work of underwater vehicle observers.
As a result, 91 km of route observations were made in a small area of the bottom, 23 thousand photographs were taken, more than 2 tons of rock samples were collected and more than 100 videos were made.
The scientific results of this expedition (it is known as "Famous") are very important. For the first time, submersibles were used not just for observations of the underwater world, but for purposeful geological research, similar to those detailed surveys that geologists conduct on land.
For the first time, direct evidence was obtained for the movement of lithospheric plates along the boundaries. In this case, the boundary between the American and African plates was investigated.
The width of the zone was determined, which is located between moving lithospheric plates. Unexpectedly, it turned out that this zone, where the earth's crust forms a system of cracks and where basalt lava flows out onto the bottom surface, that is, a new earth's crust is formed, this zone has a width of less than a kilometer.
A very important discovery was made on the slopes of underwater hills. In one of the dives of the Siana submersible, fissured loose fragments were found on a hillside, very different from various fragments of basaltic lava. After the Siana surfaced, it was found that it was manganese ore. A more detailed survey of the area of distribution of manganese ores led to the discovery of an ancient hydrothermal deposit on the bottom surface. Repeated dives yielded new materials proving that indeed, due to the emergence of thermal waters from the depths of the bottom, iron and manganese ores lie in this small section of the bottom.
During the expedition, many technical problems arose and there were failures, but the precious experience of purposeful geological research, gained over two seasons, is also an important result of this extraordinary oceanological experiment.
Methods for studying the structure of the earth's crust in the ocean differ in some features. The bottom relief is studied not only with the help of echo sounders, but also with side-scan locators and special echo sounders that give a picture of the relief within a strip equal in width to the depth of the place. These new methods give more accurate results and more accurately represent topography on maps.
On research vessels, gravimetric surveys are carried out using on-board gravimeters, and magnetic anomalies are surveyed. These data make it possible to judge the structure of the earth's crust under the ocean. The main research method is seismic sounding. A small explosive charge is placed in the water column and an explosion is made. A special receiver registers the arrival time of the reflected signals. Calculations determine the propagation velocity of longitudinal waves caused by an explosion in the thickness of the earth's crust. The characteristic velocity values make it possible to divide the lithosphere into several layers of different composition.
Currently, pneumatic devices or an electric discharge are used as a source. In the first case, a small volume of air compressed in a special device with a pressure of 250-300 atm is released (almost instantly) in the water. At a shallow depth, the air bubble expands sharply and this imitates an explosion. The frequent repetition of such explosions, caused by a device called an air gun, gives a continuous profile of seismic sounding and, therefore, a fairly detailed profile of the structure of the earth's crust throughout the tack.
A profilograph with an electric spark gap (sparker) is used in a similar way. In this version of seismic equipment, the power of the discharge that excites the oscillations is usually small, and a sparker is used to study the power and distribution of unconsolidated layers of bottom sediments.
To study the composition of bottom sediments and obtain their samples, various systems of soil pipes and bottom grabs are used. Ground pipes have, depending on the task of the study, a different diameter, they usually carry a heavy load for maximum penetration into the ground, sometimes they have a piston inside and carry one or another contactor (core breaker) at the lower end. The tube is immersed in water and sediment at the bottom to a certain depth (but usually not more than 12-15 m), and the core extracted in this way, usually called a column, rises to the deck of the vessel.
Grab grabs, which are clamshell-type devices, seem to cut out a small monolith of the surface layer of the bottom soil, which is delivered to the deck of the ship. Self-floating bottom grab models have been developed. They make it possible to do without a cable and a deck winch and greatly simplify the method of obtaining a sample. In the coastal regions of the ocean at shallow depths, vibropiston soil tubes are used. With their help, it is possible to obtain columns up to 5 m long on sandy soils.
Obviously, all of the listed devices cannot be used to obtain samples (cores) of bottom rocks that are compacted and have a thickness of tens and hundreds of meters. These samples are obtained using conventional ship-mounted drilling rigs. For relatively small depths of the shelf (up to 150-200 m), special vessels are used that carry a drilling rig and are installed at the drilling point on several anchors. Keeping the vessel at the point is carried out by adjusting the tension of the chains going to each of the four anchors.
At depths of thousands of meters in the open ocean, anchoring a ship is technically unfeasible. Therefore, a special method of dynamic positioning has been developed.
The drilling ship goes to a given point, and the accuracy of determining the location is provided by a special navigation device that receives signals from artificial earth satellites. Then a rather complex device such as an acoustic beacon is installed on the bottom. The signals from this beacon are received by the system installed on the vessel. After receiving the signal, special electronic devices determine the displacement of the vessel and instantly issue a command to the thrusters. The desired group of propellers is turned on and the position of the vessel is restored. On the deck of the deep drilling vessel, there is a drilling rig with a rotary drilling rig, a large set of pipes and a special device for lifting and screwing pipes.
Drilling vessel "Glomar Challenger" (so far the only one) carries out work on the international project of deep sea drilling in the open ocean. More than 600 wells have already been drilled, and the maximum depth of well drilling was 1300 m. Materials of deep-water drilling have yielded so many new and unexpected facts that interest in their study is extraordinary. In the study of the ocean floor, many different techniques and methods are used, and new methods using new measurement principles can be expected in the near future.
In conclusion, a brief mention should be made of one task in the overall program of ocean research, the study of pollution. The sources of ocean pollution are varied. Discharge of industrial and domestic effluents from coastal enterprises and cities. The composition of pollutants here is extremely diverse: from nuclear industry waste to modern synthetic detergents. Significant pollution is created by discharges from ocean-going ships, and sometimes by catastrophic oil spills during accidents with tankers and offshore oil wells. There is another way to pollute the ocean - through the atmosphere. Air currents carry over vast distances, for example, lead that enters the atmosphere with the exhaust gases of internal combustion engines. In the process of gas exchange with the atmosphere, lead enters the water and is found, for example, in Antarctic waters.
Pollution definitions are now organized into a dedicated international observing system. At the same time, systematic observations of the content of pollutants in the water are assigned to the relevant vessels.
The greatest distribution in the ocean is oil pollution. To control it, not only chemical methods of determination are used, but mostly optical methods. Airplanes and helicopters are equipped with special optical devices, with the help of which they determine the boundaries of the area covered with an oil film, and even the thickness of the film.
The nature of the World Ocean, this, figuratively speaking, a huge ecological system of our planet, has not yet been sufficiently studied. Evidence for this assessment is provided by recent discoveries in various areas of oceanology. Methods for studying the World Ocean are quite diverse. Undoubtedly, in the future, as new methods of research are found and applied, science will be enriched with new discoveries.
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We remember: What is the World Ocean? What parts is it divided into? What are the main shapes of the ocean floor? How does the temperature of ocean waters change? What are the types of water movement in the ocean? Under the influence of what causes are sea waves, tsunamis, ocean currents, ebbs and flows formed? What are the characteristics of marine plants and animals and how are they distributed in the ocean? What riches of the oceans are used by man? What is the negative human impact on the ocean? How to deal with pollution of the waters of the oceans?
Keywords:expedition ships, drifting stations, submersibles, artificial satellites and spacecraft.
1. Exploring the ocean in the past. The ocean has always amazed people with its expanses, power, mysterious distances. Ancient people tried in their own way to explain incomprehensible phenomena in the ocean. In their imagination, not natural processes arose, but sea spirits, and then deities. For the ancient Greeks, it was Poseidon, and for the Romans, it was Neptune.
At present, sailors of all countries do not forget about their patron Neptune and arrange a holiday in his honor.
If there are not so many unexplored territories left on land, then in the depths of the ocean there are still a lot of unknown and even mysterious things. First of all, people got acquainted with what is happening on the surface of the ocean and in coastal, shallow parts of it.
The first explorers of the ocean were divers for pearls and sea sponges. They dived without any devices and could stay under water for only a few minutes.
2. Modern research of the World Ocean. A lot of time passed before the researchers got heavy hard suits - spacesuits connected by a hose and cable to the ship. In the forties of the XX century, J.I. Cousteau invented scuba gear. This opened the way for a wide range of people to explore the depths of the sea: archaeologists, geologists, oceanologists, and divers (Fig. 110).
Despite the dangers that await researchers in the ocean, its study does not stop.
Ocean exploration is carried out with the help of special expedition ships, drifting stations, artificial Earth satellites, and underwater vehicles. One of them - a bathyscaphe - is called an underwater airship (Fig. 111).
Rice. 111. Bathyscaphe
On the bathyscaphe "Trieste" in 1960, the Swiss scientist Jacques Picard and his assistant descended into the Mariana Trench to a depth of about 10,500 m. Sometimes underwater houses - laboratories are installed at a depth of 10-20 meters.
An important role in the study of the oceans and seas belongs to artificial earth satellites and spacecraft. From satellites, for example, they study sea currents, monitor the warm current of the Gulf Stream, sea waves and ice.
The ocean is studied comprehensively. The properties of water, its movement at different depths, the characteristics of marine organisms and their distribution are clarified, depths are measured, samples of bottom sediments are taken and studied.
If it is necessary to study large areas of the ocean, scientists from different countries join their efforts. Dozens of special vessels, aircraft, underwater vehicles, and artificial Earth satellites are involved in such studies.
The results of the research are of great importance for navigation, fishing, exploration and extraction of minerals.
1. How is the World Ocean studied? 2. What role do artificial earth satellites and spacecraft play in ocean exploration? 3. Why is it necessary to study the ocean? 4* Do you know when the Neptune festival is held and what ritual it is accompanied by?
Land covers less than 30% of our planet's surface. The rest is covered by seas and oceans. Dozens of mysteries and amazing natural phenomena are associated with them. And, despite the fact that scientists have successfully explained the causes of these phenomena, they remain magnificent works of nature that amaze the imagination of people. Let's find out about 10 unusual and exciting phenomena associated with the oceans.
Icebergs don't always look perfectly white!
It is no secret that the temperature of the water in the ocean differs at different geographical latitudes. At the equator, the surface layer can warm up to +28°C and higher, while in areas close to the poles - no more than +2°C. Therefore, large icebergs can float in the Arctic and Antarctic for decades. And sometimes they turn ... into striped icebergs!
Striped icebergs form when water first thaws and then refreezes. In between, small particles of dirt, minerals, etc. get into it. After freezing, the color of the fresh iceberg layer is different from others. Thanks to this process, many multi-colored stripes can be observed on the surface of the ice block. That is, not all icebergs are white or transparent, as they are shown in the pictures. On some of them we can observe an amazing play of colors and shades. Moreover, the older the iceberg, the more stripes it has. Looking at them, it may seem that nature itself adorned these blocks of ice with a skillful hand.
9. Whirlpool
Whirlpool - a huge funnel with a lower draft, sucking everything that is nearby
The word "whirlpool" seems to deliberately warn people that this phenomenon should be feared. Interestingly, it was first used by the famous writer Edgar Allan Poe. He described it as a "destructive current". In fact, the ocean whirlpool is a powerful funnel with a lower thrust, slowly but surely sucking in everything that is nearby. They are of three types - permanent (always existing in the same place), seasonal (caused by certain climatic conditions) and episodic (occurring, for example, during earthquakes).
In the seas and oceans, whirlpools are most often caused by the collision of tidal or ebb waves with oncoming currents. At the same time, water in them can move at speeds of hundreds of kilometers per hour.
It is interesting: The width of whirlpools sometimes reaches 3-5 kilometers. Not only small yachts and fishing boats, but also large liners can become victims of such phenomena. You may remember the shocking incident when, in 2011, off the coast of Japan, a ship with a hundred passengers on board was pulled into the whirlpool formed after an earthquake.
Previously, people believed in legends that whirlpools would certainly drag them to the very bottom of the ocean. But scientists have debunked such myths.
8. Red tide
The largest Red Tide can be observed in the Gulf of Florida
Waves of saturated bright red and orange hues are an amazingly beautiful natural phenomenon. But enjoying the red tides is too often unhealthy, because they are fraught with no small danger.
Algae blooms (which cause the water to turn scarlet) can be so intense that plants begin to produce all sorts of toxins and chemicals. Some of them dissolve in water, some get into the air. Toxins harm aquatic life, seabirds and even humans.
The largest Red Tide on the planet is observed annually off the coast of the Gulf of Florida in June-July.
7. Brinicle (salty icicle)
Brinicle spreads an ice net across the bottom of the sea, from which not a single living creature can get out
An amazing work of nature - a salty icicle, is something unimaginable. When a brinicle is finally formed, it looks something like a crystal lowered into water. Salty icicles are formed when water from melting ice seeps into the sea. Considering that very low air and water temperatures are needed for the formation of salty icicles, they can only be observed in the cold waters of the Arctic and off the coast of Antarctica.
It is interesting: Brinicles are fraught with great danger to the flora and fauna of the ocean. At the moment of contact with them, starfish, fish and even algae either freeze and freeze, or receive significant cuts.
The generally accepted model for the formation of brinicles was described by oceanographer Silje Martin as early as 1974. For more than 30 years, only scientists could witness this vivid oceanic performance. But in 2011, the formation of a sea icicle was captured on video by a BBC cameraman.
A stream of salty water flowing out of an ice block is so cold that the liquid surrounding it freezes almost instantly. Seconds after a brinicle enters the ocean, a fragile armor of porous ice forms around it. When the critical mass is reached, the icicle falls to the bottom. Then she begins to unravel her cold nets further. Any animal caught in them is doomed to death. In front of the operators, the "killer icicle" sprouted several meters in 3 hours and reached the ocean floor. After that, in some 15 minutes, the brinicle destroyed all marine life that was within a radius of four meters.
6. The longest wave on Earth
Brazilians call the process of formation of the longest wave Pororoca
Weather conditions have a huge impact on ocean waters. It is not surprising that some natural phenomena can be observed only in a certain season with a combination of many factors contributing to them.
So, the longest wave on the planet can be seen in Brazil no more than 2 times a year. At the end of February and then at the beginning of March, a huge volume of water from the Atlantic Ocean rises up the mouth of the Amazon River. When the current of the river collides with the tidal forces of the ocean, the longest wave on Earth is formed. In Brazil, this phenomenon is called Pororoca. The height of the waves formed during this phenomenon sometimes reaches 3.5-4 meters. And you can hear the sound of the wave half an hour before it crashes onto the shore with a roar. Sometimes Pororoka destroys coastal houses or uproots trees.
5. Frosty Flowers
Thousands of amazing frosty flowers in arctic waters
Few people know about the existence of these delicate, charming flowers. Frosty flowers are formed quite rarely - only on young ice in cold sea water. Their formation occurs at low temperatures in calm weather. The diameter of such formations usually does not exceed four centimeters, but they look like crystal copies of real flowers. They contain a lot of salt, which explains the crystallized appearance of frosty flowers.
It is interesting: If millions of these flowers form in a small area of the sea, they begin to “release” salt into the air!
The sea can not only create conditions for life and support it. It changes itself, like a living organism. And frosty flowers are an example of one of the most beautiful pieces of art created by the oceans.
4. Killer waves
Rogue killer waves can reach a height of 25 meters or more. The reasons for their formation are not known for certain.
As a rule, it is not difficult to determine the moment of wave formation. But there are so-called killer waves, which, in fact, appear out of nowhere and show no signs of their approach.
It is interesting: Usually killer waves are found in the open ocean far from land. They can appear even in clear weather in the absence of strong winds. The reasons have not yet been established. Their size is simply colossal. The height of the wandering killer waves can reach 30 meters, and sometimes more!
For a long time, scientists considered wandering waves to be a fiction of sailors, because they did not fit into any existing mathematical models of the occurrence and behavior of waves. The fact is that from the point of view of classical oceanology, a wave with a height of more than 20.7 meters cannot exist in terrestrial conditions. There was also a lack of reliable evidence of their existence. But on January 1, 1995, on the Norwegian oil platform Dropner, located in the North Sea, instruments recorded a wave 25.6 meters high. They called it the Dropner wave. Soon research began within the framework of the MaxWave project. The specialists monitored the Earth's water surface using two radar satellites launched by the European Space Agency. In just 3 weeks, 10 single stray waves over 25 meters high were recorded in the oceans.
After that, scientists were forced to take a fresh look at the cases of the death of huge ships - container ships and supertankers. Rogue waves have been included among the likely causes of these catastrophes. Later it was proved that in 1980 the 300-meter English cargo ship Derbyshire sank off the coast of Japan after colliding with a giant wave that broke through the cargo hatch and flooded the holds. Then 44 people died.
Killer waves are a sailor's nightmare that appears in many stories and legends. They hide something mysterious and sinister. It seems incredible that predicting the appearance of such a wall of water is almost impossible. The thought of killer waves will definitely make you reconsider your relationship with the ocean. It is unlikely that you will continue to believe that in calm weather you can sail on a boat or yacht far from the coast without fear for your life.
3. The meeting point of the Baltic Sea with the North
On the left is the North Sea, on the right is the Baltic. Surprisingly, their waters don't mix.
In the Danish province of Skagen, one can observe an amazing phenomenon that previously caused a lot of controversy among scientists. In a picturesque place, 2 neighboring seas meet - the Baltic and the North. Surprisingly, they do not mix, as if separated by an invisible wall. The color of the water in each sea is different, this allows you to visually determine the border between them.
According to oceanologists, the density of sea waters differs, as does their salinity (it is 1.5 times higher in the North Sea). Because of this, each sea remains on its own side of the "watershed", not mixing with the neighboring one and not yielding to it. In addition to the composition of the water, the boundary is so pronounced due to the opposite currents in the two straits. Running into each other, they form colliding waves.
Interestingly, the meeting of the North Sea with the Baltic Sea is mentioned in religious literature - in the Koran. It is not clear how the ancient Muslims got to the territory of modern Denmark to see this fantastic sight.
2. Bioluminescence
The glow of the ocean in coastal waters is a fantastic sight
The bioluminescence of water is a phenomenon that looks amazing in photographs and is even more spectacular in reality. The glow of the ocean is due to the simplest algae - dinoflagellates, which make up most of the plankton.
A tiny molecule - the substrate luciferin, is oxidized under the influence of the luciferase enzyme and oxygen. The released energy does not turn into heat, but excites the molecules of the substance, which emits photons. The type of luciferin determines the frequency of light, that is, the color of the glow.
It is best to observe the glow of the ocean during the reproduction of unicellular algae (usually - no more than 3 weeks a year). There are so many tiny lights that sea water becomes like milk, however, painted in bright blue. However, one should be careful when admiring the bioluminescence of the sea or ocean: many algae produce toxins that are dangerous to human health. Therefore, during the period of their reproduction and the greatest intensity of the glow, it will still be better to observe a bright tide while on the shore. And definitely at night! It may seem that huge searchlights are hidden under the water, illuminating it from the depths.
1. Phenomenon of the Milky Sea
The glow of the ocean, caused by the phenomenon of bioluminescence, can sometimes be seen even from space!
The Sea of Milk phenomenon is observed in the Indian Ocean, and this is one of the manifestations of the bioluminescence process.
It is interesting: In certain areas of the ocean, ideal conditions are created for the reproduction of bacteria. Then huge volumes of salt water begin to glow and are colored with light blue lights. Sometimes bacteria illuminate such large areas of water that they can be easily seen even from space. Such a spectacle will not leave anyone indifferent!
This phenomenon has been observed for more than a century. The glow of the water was often observed by sailors in antiquity, it made them enthusiastically peer into the depths of the ocean. However, if earlier people could not find an explanation for this phenomenon, then in our time everything is known about its nature. But this does not prevent the glow of water from being a fantastic sight.
Such phenomena show all the beauty and diversity of the majestic oceans. Watching them, you involuntarily catch yourself thinking that human civilization, no matter how advanced it may be, will not be able to create anything like this! After all, people are only temporary guests on this amazing planet. And we must not destroy, but preserve all the splendor of nature for future generations.