Earth's magnetic field. Why do planets need a magnetic field?
Bibliographic description: Korobko P. I., Frolova V. M., Lobanov I. A., Titova N. A., Panshina S. G., Panshin E. A. Using the Earth’s magnetic field in solving problems in the Far North // Young scientist. 2016. No. 5. P. 62-68..06.2019).
For most territories of the Far North, the only possible method of transport is by plane. During the summer navigation season, sea traffic is used only for the delivery of goods. There is no passenger service due to the long length of sea routes. In principle, there are no railway or road connections with the “mainland”.
Another very pressing problem in the Far North is energy. If in other warmer regions of the country energy problems are successfully solved by the operation of hydroelectric power plants, then in areas adjacent to the coast of the Arctic Ocean such an option loses its advantages (due to freezing of rivers in winter), and in some places it is not feasible due to too small a difference in altitude (necessary for the operation of a hydroelectric station).
The construction of power plants using fossil fuels in polar climates and permafrost is not economically justified; their payback period is too long; in addition, oil and gas fields may be located at a considerable distance from places where electricity is required. Thus, fuel is transported to many coastal areas by sea.
It is obvious that the region's dependence on periodic fuel supplies and on irregular passenger and cargo traffic cannot allow the regions to develop to their full potential. This article proposes a technical solution for transport communication between the settlements of Salekhard - Anadyr, as well as methods for obtaining energy directly in areas in need, which will open up new prospects for the development of facilities located in the Far North.
Characteristics that the vehicle being developed must meet:
– use of renewable, safe, environmentally friendly and high-potential energy sources. In this case, preference should be given to a more expensive, but operating on the basis of renewable resources and environmentally friendly source of energy;
– use of the latest technologies and innovative solutions.
To implement this project, we conducted the following research:
– analysis of the geographical and climatic features of the territories through which the route “Anadyr - Salekhard” should run;
– analysis of the transport used on the territory of the proposed route;
– search for possible renewable energy sources.
Before starting to develop a technical solution for transport communication between the settlements of Salekhard - Anadyr, we analyzed the geographical and climatic features of the territories through which the Anadyr - Salekhard route should run. Briefly, we can say that the cities of Anadyr and Salekhard are located at approximately the same geographical latitude. The likely route runs through the polar zone with a subarctic climate. This territory is part of the aurora zone. A small influx of solar radiation, flat terrain, open to the invasion of air masses from the Arctic in the summer and supercooled continental masses in the winter, determine the sharp continentality and severity of the climate.
Permafrost, an abundance of swamps, lakes and rivers. Long winters, short cool summers, strong winds, insignificant snow cover - all this contributes to freezing of the soil to great depths.
An analysis of the transport used on the territory of the proposed route showed that due to unstable weather prone to rain, snowfall and strong winds, aircraft flights may be delayed or completely cancelled. During certain periods in spring and autumn, planes do not fly at all. The existing sea communication during the summer navigation season is used only for the delivery of goods. There is no passenger service due to the long length of sea routes. In principle, there are no railway or road connections with the “mainland”.
Our group carried out an analysis of the latest achievements of science and technology in the field of transport and the use of new types of energy that can be used to implement the project.
More recently, at the end of the last century (1986), a new type of superconductor was discovered that did not require very low temperatures; at that time, the known superconductors - mercury and lead - acquired superconducting properties at temperatures down to -270 ° C. Currently, ceramic conductors acquire superconducting properties at temperatures from -191°C to -183°C. This temperature can be maintained using liquid nitrogen (it is formed at a temperature of -195.75°C). This discovery dramatically reduced the cost of superconductors.
This discovery will make it possible to create powerful supermagnets that hold vehicles like trains in the air.
To set a magnetic levitation train in motion, a jet of compressed air is sufficient to overcome the force of air resistance.
But to use liquid nitrogen, refrigeration equipment is required. And for the operation of refrigeration equipment, a source of energy is required. Where can I get it in the tundra? A source of energy is required.
Search for energy sources.
When considering the climatic and geographical features of the territory of the proposed route, we found out that the route is located in the zone of auroras.
The aurora is the most magnificent phenomenon that a person can observe on Earth. But the aurora is not only a grandiose and beautiful spectacle. It is the only manifestation of the impact of solar radiation on near-Earth space and the earth's atmosphere that can be seen with the naked eye.
Aurora is the glow of the earth's atmosphere under the influence of streams of solar particles that invade the atmosphere.
Solar streams approaching the Earth flow around it, since the Earth is protected from these particles by its own magnetic field. However, the configuration of the Earth's magnetic field is such that some of these particles penetrate into the magnetosphere, and from it into the upper atmosphere. Possessing a large amount of energy and penetrating into the Earth's atmosphere, these particles collide with atoms and molecules of the upper atmosphere causing its glow.
The aurora can be compared to the Firebird from folk legends and fairy tales. It turns out that our scientists have already figured out how to catch this Firebird by the tail. And if we use this in this project, then we will give life to the unique invention of the Russian physicist N.P. Danilkin (“Institute of Applied Geophysics named after Academician E.K. Fedorov.” He invented a unique method for obtaining electrical energy from the upper layers of the atmosphere in the zone auroras, called the ionosphere.
The essence of the method is as follows.
It is planned to use the possibility of extracting electrical energy from the ionosphere, where currents flow at altitudes of more than 100 km above the Earth's surface. Such a power plant should be located on the surface of the Earth and will draw energy from near-Earth space, using the transformation of electromagnetic energy, which is a consequence of the work of forces of a planetary nature, into electric current for technical purposes.
It turns out that the main “pumping” of energy along the chain of solar-terrestrial connections occurs as a result of solar flares, which are accompanied by magnetic storms. However, in the aurora zone and in a calm state, and even more so during periods of magnetic storms, the magnetic field strength on the Earth's surface undergoes continuous changes.
Therefore, if a single-wire circuit is placed on the surface of the Earth, then in such a circuit during the period of change in the magnetic field strength, in accordance with the laws of physics, an electromotive force arises, causing an electric current.
The total power of currents constantly flowing in the Earth's ionosphere significantly exceeds the needs of humanity. If you learn how to connect to these currents technologically competently, then the whole process will turn out to be environmentally friendly and safe.
In order to increase the power of such a power plant, the required number of circuits can be connected in parallel to this circuit.
There is also a way to reduce the electrical resistance of the circuit by using the phenomenon of superconductivity.
Of course, before building power plants and laying an overpass for a magnetic levitation train, it is necessary to carry out a lot of serious calculations, experiments and development work. Despite this, there are already facts proving the technological feasibility and potential of such a power plant. For example, this is well illustrated by the events that happened in the province of Quebec (Canada) on March 13–14, 1989. At this time, after a powerful flare on the Sun and the passage of a large charge of energy through a chain of processes on the Sun-Earth line, the characteristics of the electromagnetic induction field in this zone turned out to be located in such a way that strong induction currents arose in high-voltage power lines. Moreover, the power of these currents turned out to be such that the fuses turned off 40% of the power of the entire Hydro-Quebec power system, which amounted to 9 GW. Note that these powerful induction currents arose in a system that was not oriented toward receiving them!
Another famous event occurred on September 1–2, 1859. It was the most powerful geomagnetic storm in recorded history. A complex of events that includes both a geomagnetic storm and the powerful active phenomena on the Sun that caused it is sometimes called the “Carrington Event.”
From August 28 to September 2, numerous spots and flares were observed on the Sun. Just after noon on September 1, British astronomer Richard Carrington observed the largest flare, which caused a large release of mass of solar radiation. It rushed towards the Earth and reached it in 18 hours, which is very fast, since this distance is usually covered by the ejection in 3-4 days. The ejection moved so quickly because previous ejections had cleared the way for it. The largest geomagnetic storm in recorded history began, causing the failure of telegraph systems throughout Europe and North America. Northern lights have been observed all over the world, even over the Caribbean;
As a result, on September 1 and 2, 1859, the entire telegraph system in North America and throughout Europe failed: transmission lines sparked, telegraph paper spontaneously ignited, and some devices, such as the telegraph, calmly continued to operate, having already been disconnected from the power source.
From the calculations of the Russian physicist N.P. Danilkin (Institute of Applied Geophysics named after Academician E.K. Fedorov), two conclusions can be drawn:
– the proposed method is capable of extracting electricity sufficient for industrial purposes from the ionosphere;
– the ionosphere and magnetosphere have sufficient energy reserves for these purposes.
The main disadvantages of this method of generating energy at the level of modern technology are the very impressive size of the operating circuit and the obvious high cost of its creation. However, the advantages of the method may outweigh these disadvantages, especially if new materials convenient for solving this problem are discovered.
The advantages of this power plant include:
– such a station, once built, will not wear out and theoretically will function as long as the Sun shines and the “Sun-Earth” chain of connections operates;
– the technological process of extracting energy from the ionosphere turns out to be environmentally friendly and safe, and there is not even a theoretical possibility of causing a catastrophe.
Conclusion.
Experimental confirmation of the developed project in laboratory conditions.
In order to obtain experimental confirmation of the idea of producing electricity from the ionosphere, it is enough to carry out the experiment demonstrated in the school physics course.
Having completed this experiment, we examined what the phenomenon of electromagnetic induction is. For the experiment, we needed a galvanometer, a permanent magnet and a coil with wire wound on it. The ends of the wire were connected to the coil. When we pushed a permanent magnet inside the coil, the galvanometer deflected. This means that an electric current has arisen in the circuit.
Since we do not have any current source in the circuit, it is logical to assume that the current arises due to the appearance of a magnetic field inside the coil. When we pull the magnet back out of the coil, we will see that the galvanometer readings will change again, but its needle will deviate in the opposite direction. We again received a current, but this time directed in the other direction.
Rice. .1 The phenomenon of electromagnetic induction
After this, we performed a similar experiment with the same elements, only in this case we fixed the magnet motionless. Now we removed and put on the magnet the coil itself, connected to the galvanometer. As a result, we received similar events. Deflecting, the galvanometer needle showed us the appearance of current in the circuit. At the same time, when the magnet was stationary, there was no current in the circuit - the needle stood at zero.
Rice. 2. Conducting an experiment of the project in laboratory conditions
The coil can be replaced with a conducting circuit and experiments can be done on moving and rotating the circuit itself in a constant magnetic field, or a magnet inside a stationary circuit. The results will be the same - the appearance of current in the circuit when the magnet or circuit moves.
Thus, the experiment conducted allows us to conclude:
With any change in the magnetic flux penetrating the circuit of a closed conductor, an electric current arises in this conductor. In this case, the electric current exists in during the entire process of changing the magnetic flux.
The same principle is used in the method of generating electricity from the ionosphere. Our planet Earth is a huge magnet with a constant magnetic field. Due to the impact of solar radiation on our planet, the Earth's magnetic field undergoes constant changes. Particularly large values of magnetic field variations are observed in the aurora zone. Magnetic storms and substorms can often be observed there.
Description of the technical solution.
After carrying out the planned studies, the following decision was prepared:
Transport connecting the two regions in the Far North should be a comfortable magnetic levitation train using the latest generation of superconductors. If it is not possible to practically implement the idea of using superconductors, use the property of repulsion of magnet poles of the same name.
Rice. 3. Project diagram
1) The energy required to power the overpass and magnetic levitation train is obtained using the method of generating electricity from the ionosphere. In addition, powerful wind generators can be placed along the entire route and the energy of strong winds in these places can be used.
2) If the platform from which the train is to depart is installed at an altitude of 400 meters, and then the road along which the magnetic levitation train will slide is laid downhill, then by the time it reaches Earth level the train will have a speed of about 310 km/h. Approaching the destination station, the road along which the train is moving will slowly begin to rise to 400 m. And at the arrival point the train will stop. If it does not have enough speed in any section, the train will be given the required speed using a jet of compressed air.
Rice. 4. Departure and arrival platform diagram
Execution plan for the proposed project.
To implement the project it is necessary:
1) Conducting research work on the development of magnetic levitation transport using electrical energy obtained from the upper layers of the atmosphere in the aurora zone, called the ionosphere (the period of completion of the work, according to experts, is 2–3 years);
2) Conducting development work to create a magnetic levitation vehicle using electrical energy obtained from the upper layers of the atmosphere in the aurora zone, called the ionosphere. Result of the work: a prototype of a road section with a magnetic levitation train using electricity obtained from the upper layers of the atmosphere in the aurora zone, called the ionosphere (the work period is estimated by experts to be 5–7 years).
– implementation of the project on the Anadyr-Salekhard section. (work completion period, according to specialists, is 25–30 years).
Performance assessment andeffectiveness.
Conclusion
On Earth there is an alternative, environmentally friendly and renewable source of planetary electromagnetic energy, continuously replenished by processes originating in the Sun and coming to the Earth along a chain of solar-terrestrial connections. The modern technological level makes it possible to use this energy.
Disadvantages of the project
– impressive size
- the high cost of its creation.
Advantages of the project:
– wear resistance of the power plant;
– an inexhaustible source of energy (Sun);
– environmental friendliness;
– profitability due to free electricity;
– having such a source of electricity, it is possible to develop infrastructure throughout the territory where the train overpass lies.
– prospects for the development of new territories.
Literature:
- Kaku M. Physics of the future. Translation from English. Moscow 2014;
- Danilkin N.P. “On the possibility of obtaining electrical energy from the ionosphere” “Electricity”. 1996, no. 4, p. 71–75;
- Dmitriev A. N., Shitov A. V., Technogenic impact on the natural processes of the Earth. Gorno-Altaisk, 2001 p. 9;
- Dokumentika.org [Electronic resource]. - Access mode: http://dokumentika.org/zemli/solnechnaya-burya-1859-goda.
The Earth's magnetic field is a formation generated by sources inside the planet. It is the object of study in the corresponding section of geophysics. Next, let's take a closer look at what the Earth's magnetic field is and how it is formed.
general information
Not far from the Earth's surface, approximately at a distance of three of its radii, the lines of force from the magnetic field are located along a system of “two polar charges”. There is an area called the "plasma sphere" here. With distance from the surface of the planet, the influence of the flow of ionized particles from the solar corona increases. This leads to compression of the magnetosphere from the side of the Sun, and, on the contrary, the Earth’s magnetic field is stretched from the opposite, shadow side.
Plasma Sphere
The directional movement of charged particles in the upper layers of the atmosphere (ionosphere) has a noticeable effect on the Earth's surface magnetic field. The location of the latter is one hundred kilometers and above from the surface of the planet. The Earth's magnetic field holds the plasmasphere. However, its structure strongly depends on the activity of the solar wind and its interaction with the confining layer. And the frequency of magnetic storms on our planet is determined by flares on the Sun.
Terminology
There is a concept "magnetic axis of the Earth". This is a straight line that passes through the corresponding poles of the planet. The "magnetic equator" is the large circle of the plane perpendicular to this axis. The vector on it has a direction close to horizontal. The average strength of the Earth's magnetic field is significantly dependent on geographic location. It is approximately equal to 0.5 Oe, that is, 40 A/m. At the magnetic equator, this same indicator is approximately 0.34 Oe, and near the poles it is close to 0.66 Oe. In some anomalies of the planet, for example, within the Kursk anomaly, the indicator is increased and amounts to 2 Oe. Field lines of the Earth’s magnetosphere with a complex structure , projected onto its surface and converging at its own poles, are called “magnetic meridians”.
Nature of occurrence. Assumptions and conjectures
Not long ago, the assumption about the connection between the emergence of the Earth’s magnetosphere and the flow of current in the liquid metal core, located at a distance of a quarter to a third of the radius of our planet, gained the right to exist. Scientists also have an assumption about the so-called “telluric currents” flowing near the earth’s crust. It should be said that over time there is a transformation of formation. The Earth's magnetic field has changed several times over the past one hundred and eighty years. This is recorded in the oceanic crust, and this is evidenced by studies of remanent magnetization. By comparing areas on both sides of the ocean ridges, the time of divergence of these areas is determined.
Earth's magnetic pole shift
The location of these parts of the planet is not constant. The fact of their displacements has been recorded since the end of the nineteenth century. In the Southern Hemisphere, the magnetic pole shifted by 900 km during this time and ended up in the Indian Ocean. Similar processes are taking place in the Northern part. Here the pole moves towards a magnetic anomaly in Eastern Siberia. From 1973 to 1994, the distance by which the site moved here was 270 km. These pre-calculated data were later confirmed by measurements. According to the latest data, the speed of movement of the magnetic pole of the Northern Hemisphere has increased significantly. It grew from 10 km/year in the seventies of the last century to 60 km/year at the beginning of this century. At the same time, the strength of the earth's magnetic field decreases unevenly. So, over the past 22 years, in some places it has decreased by 1.7%, and somewhere by 10%, although there are also areas where it, on the contrary, has increased. The acceleration in the displacement of the magnetic poles (by approximately 3 km per year) gives reason to assume that their movement observed today is not an excursion, but another inversion.
This is indirectly confirmed by the increase in the so-called “polar gaps” in the south and north of the magnetosphere. The ionized material of the solar corona and space rapidly penetrates into the resulting expansions. As a result, an increasing amount of energy is collected in the circumpolar regions of the Earth, which in itself is fraught with additional heating of the polar ice caps.
Coordinates
In the science of cosmic rays, geomagnetic field coordinates are used, named after the scientist McIlwain. He was the first to propose the use of them, since they are based on modified versions of the activity of charged elements in a magnetic field. For a point, two coordinates are used (L, B). They characterize the magnetic shell (McIlwain parameter) and field induction L. The latter is a parameter equal to the ratio of the average distance of the sphere from the center of the planet to its radius.
"Magnetic inclination"
Several thousand years ago, the Chinese made an amazing discovery. They found that magnetized objects can be positioned in a certain direction. And in the middle of the sixteenth century, Georg Cartmann, a German scientist, made another discovery in this area. This is how the concept of “magnetic inclination” appeared. This name refers to the angle of deviation of the arrow up or down from the horizontal plane under the influence of the planet’s magnetosphere.
From the history of research
In the region of the northern magnetic equator, which is different from the geographic equator, the northern end moves downwards, and in the southern, on the contrary, upwards. In 1600, the English physician William Gilbert first made assumptions about the presence of the Earth's magnetic field, which causes a certain behavior of objects that were previously magnetized. In his book, he described an experiment with a ball equipped with an iron arrow. As a result of his research, he came to the conclusion that the Earth is a large magnet. The English astronomer Henry Gellibrant also conducted experiments. As a result of his observations, he came to the conclusion that the Earth's magnetic field is subject to slow changes.
José de Acosta described the possibility of using a compass. He also established the difference between the Magnetic and North Poles, and in his famous History (1590) the theory of lines without magnetic deflection was substantiated. Christopher Columbus also made a significant contribution to the study of the issue under consideration. He was responsible for the discovery of the variability of magnetic declination. Transformations are made dependent on changes in geographic coordinates. Magnetic declination is the angle of deviation of the needle from the North-South direction. In connection with the discovery of Columbus, research intensified. Information about what the Earth's magnetic field is was extremely necessary for navigators. M.V. Lomonosov also worked on this problem. To study terrestrial magnetism, he recommended conducting systematic observations using permanent points (similar to observatories). It was also very important, according to Lomonosov, to do this at sea. This idea of the great scientist was realized in Russia sixty years later. The discovery of the Magnetic Pole on the Canadian archipelago belongs to the polar explorer Englishman John Ross (1831). And in 1841 he discovered another pole of the planet, but in Antarctica. The hypothesis about the origin of the Earth's magnetic field was put forward by Carl Gauss. He soon proved that most of it is fed from a source inside the planet, but the reason for its minor deviations is in the external environment.
100 great secrets of the Earth Volkov Alexander Viktorovich
How does the Earth's magnetic field arise?
If the Earth did not have a magnetic field, then both it itself and the world of living organisms inhabiting it would look completely different. The magnetosphere, like a huge protective screen, protects the planet from cosmic radiation that constantly bombards it. The power of the flow of charged particles emanating not only from the Sun, but also from other celestial bodies can be judged by how the Earth’s magnetic field is deformed. For example, under the pressure of the solar wind, the field lines on the side facing the Sun are pressed to the Earth, and on the opposite side they flutter like a comet's tail. As observations show, the magnetosphere extends 70-80 thousand kilometers towards the Sun and many millions of kilometers in the opposite direction from it.
This screen performs its functions most reliably where it is least deformed, where it is located parallel to the surface of the Earth or slightly inclined to it: near the equator or in temperate latitudes. But closer to the poles, flaws are discovered in it. Cosmic radiation penetrates the Earth's surface and, colliding in the ionosphere with charged particles (ions) of the air shell, generates a colorful effect - flashes of the aurora. If this screen did not exist, cosmic radiation would continuously penetrate to the surface of the planet and cause mutations in the genetic heritage of living organisms. Laboratory experiments also show that the absence of terrestrial magnetism negatively affects the formation and growth of living tissues.
The mysteries of the Earth's magnetic field are closely related to its origin. Our planet does not at all resemble a bar magnet. Its magnetic field is much more complex. There are different theories explaining why the Earth has this field. Indeed, in order for it to exist, one of two conditions must be met: either there is a huge “magnet” inside the planet - some kind of magnetized body (for a long time scientists believed so), or an electric current flows there.
Recently, the most popular theory is the earthly “dynamo”. Back in the mid-1940s, it was proposed by the Soviet physicist Ya.I. Frenkel. More than 90 percent of the Earth’s magnetic field is generated due to the operation of this “dynamo.” The remaining part is created by magnetized minerals contained in the earth's crust.
Computer model of the Earth's magnetic field
How does the Earth's magnetic field arise? At a distance of approximately 2,900 kilometers from its surface, the earth's core begins - that area of the planet that researchers will never be able to reach. The core consists of two parts: a solid inner core, compressed under a pressure of 2 million atmospheres and containing mainly iron, and a molten outer part, which behaves very chaotically. This melt of iron and nickel is constantly in motion. The magnetic field is created due to convective flows in the outer core. These flows are maintained by a noticeable temperature difference between the Earth's solid inner core and the mantle.
The inner part of the core rotates faster than the outer one and plays the role of a rotor - the rotating part of the electric generator, while the outer part plays the role of a stator (its stationary part). An electric current is excited in the molten substance of the outer core, which, in turn, generates a powerful magnetic field. This is the principle of a dynamo. In other words, the earth's core is a huge electromagnet. The lines of force of the magnetic field created by it begin in the area of one pole of the Earth and end in the area of the other pole. The shape and intensity of these lines vary.
Scientists believe that the Earth’s magnetic field originated at the time when the formation of the planet was just underway. Perhaps the Sun played a decisive role. It launched this natural “dynamo”, which continues to work today.
The core is surrounded by a mantle. Its lower layers are under great pressure and heated to very high temperatures. At the boundary separating the mantle and core, intense heat exchange processes occur. Heat transfer plays a key role. Heat flows to the colder mantle from the hot core of the Earth, and this affects the convective flows in the core itself and changes them.
In subduction zones, for example, sections of the seafloor sink deep into the Earth, almost reaching the boundary separating the mantle and core. These pieces of lithospheric plates, “sent” for melting into the bowels of the planet, are noticeably colder than the part of the mantle where they ended up. They cool the surrounding areas of the mantle, and heat from the Earth’s core begins to flow here. This process is very long. Calculations show that sometimes it is only after hundreds of millions of years that the temperature of the cooled areas of the mantle equalizes.
In turn, the hot substance, rising in the form of huge jets from the boundary separating the mantle and core, reaches the surface of the planet. This circulation of matter, these complex processes of flowing up and down, on the “Earth’s elevator” of either hot or very cold matter, undoubtedly influence the operation of the natural “dynamo”. Sooner or later it loses its usual rhythm, and then the magnetic field it creates begins to change. Computer models show that from time to time everything can end with a change in the magnetic poles.
There is nothing unusual about this reversal of poles. This has happened often in the history of our planet. However, there were eras when the pole change stopped. For example, in the Cretaceous period they did not change places for almost 40 million years.
Trying to explain this phenomenon, French researchers led by Francois Petreli drew attention to the position of the continents relative to the equator. It turned out that the more continents there are in one of the Earth’s hemispheres, the more often its magnetic field changes its direction. If, on the contrary, the continents are located symmetrically relative to the equator, then the magnetic field remains stable for many millions of years.
So, maybe the position of the continents affects convective flows in the outer part of the core? In this case, this influence occurs through subduction zones. When almost all the continents are in one hemisphere, there will be more subduction zones. The massive, cold crust will continue to sink toward the boundary separating the mantle and core and accumulate there. The resulting congestion will undoubtedly disrupt the heat exchange between the mantle and the core. The computer model shows that convective flows in the outer core also shift because of this. Now they too are asymmetrical relative to the equator. Obviously, with such an arrangement, the earthly “dynamo” is easier to unbalance. She is like a person standing on one leg and ready to lose her balance from a slight push. So the magnetic field suddenly “turns over”.
So, it is very likely that the change of magnetic poles is influenced by tectonic processes occurring on our planet, and, above all, by the movement of continents. Further paleomagnetic research can clarify this. In any case, scientists are discovering more and more facts that indicate that there is a certain connection between the movement of lithospheric plates on the Earth’s surface and the “dynamo” that creates the Earth’s magnetic field and is located in the very center of the planet .
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According to modern ideas, it was formed approximately 4.5 billion years ago, and from that moment our planet has been surrounded by a magnetic field. Everything on Earth, including people, animals and plants, is affected by it.
The magnetic field extends to an altitude of about 100,000 km (Fig. 1). It deflects or captures solar wind particles that are harmful to all living organisms. These charged particles form the Earth's radiation belt, and the entire region of near-Earth space in which they are located is called magnetosphere(Fig. 2). On the side of the Earth illuminated by the Sun, the magnetosphere is limited by a spherical surface with a radius of approximately 10-15 Earth radii, and on the opposite side it is extended like a comet's tail over a distance of up to several thousand Earth radii, forming a geomagnetic tail. The magnetosphere is separated from the interplanetary field by a transition region.
Earth's magnetic poles
The axis of the earth's magnet is inclined relative to the earth's rotation axis by 12°. It is located approximately 400 km away from the center of the Earth. The points at which this axis intersects the surface of the planet are magnetic poles. The Earth's magnetic poles do not coincide with the true geographic poles. Currently, the coordinates of the magnetic poles are as follows: north - 77° north latitude. and 102°W; southern - (65° S and 139° E).
Rice. 1. The structure of the Earth’s magnetic field
Rice. 2. Structure of the magnetosphere
Lines of force running from one magnetic pole to another are called magnetic meridians. An angle is formed between the magnetic and geographic meridians, called magnetic declination. Every place on Earth has its own declination angle. In the Moscow region the declination angle is 7° to the east, and in Yakutsk it is about 17° to the west. This means that the northern end of the compass needle in Moscow deviates by T to the right of the geographic meridian passing through Moscow, and in Yakutsk - by 17° to the left of the corresponding meridian.
A freely suspended magnetic needle is located horizontally only on the line of the magnetic equator, which does not coincide with the geographical one. If you move north of the magnetic equator, the northern end of the needle will gradually descend. The angle formed by a magnetic needle and a horizontal plane is called magnetic inclination. At the North and South magnetic poles, the magnetic inclination is greatest. It is equal to 90°. At the North Magnetic Pole, a freely suspended magnetic needle will be installed vertically with its northern end down, and at the South Magnetic Pole its southern end will go down. Thus, the magnetic needle shows the direction of the magnetic field lines above the earth's surface.
Over time, the position of the magnetic poles relative to the earth's surface changes.
The magnetic pole was discovered by explorer James C. Ross in 1831, hundreds of kilometers from its current location. On average, it moves 15 km in one year. In recent years, the speed of movement of the magnetic poles has increased sharply. For example, the North Magnetic Pole is currently moving at a speed of about 40 km per year.
The reversal of the Earth's magnetic poles is called magnetic field inversion.
Throughout the geological history of our planet, the Earth's magnetic field has changed its polarity more than 100 times.
The magnetic field is characterized by intensity. In some places on Earth, magnetic field lines deviate from the normal field, forming anomalies. For example, in the area of the Kursk Magnetic Anomaly (KMA), the field strength is four times higher than normal.
There are daily variations in the Earth's magnetic field. The reason for these changes in the Earth's magnetic field is electric currents flowing in the atmosphere at high altitudes. They are caused by solar radiation. Under the influence of the solar wind, the Earth's magnetic field is distorted and acquires a “trail” in the direction from the Sun, which extends for hundreds of thousands of kilometers. The main cause of the solar wind, as we already know, is the enormous ejections of matter from the solar corona. As they move towards the Earth, they turn into magnetic clouds and lead to strong, sometimes extreme disturbances on the Earth. Particularly strong disturbances of the Earth's magnetic field - magnetic storms. Some magnetic storms begin suddenly and almost simultaneously across the entire Earth, while others develop gradually. They can last for several hours or even days. Magnetic storms often occur 1-2 days after a solar flare due to the Earth passing through a stream of particles ejected by the Sun. Based on the delay time, the speed of such a corpuscular flow is estimated at several million km/h.
During strong magnetic storms, the normal operation of the telegraph, telephone and radio is disrupted.
Magnetic storms are often observed at latitude 66-67° (in the aurora zone) and occur simultaneously with auroras.
The structure of the Earth's magnetic field varies depending on the latitude of the area. The permeability of the magnetic field increases towards the poles. Over the polar regions, the magnetic field lines are more or less perpendicular to the earth's surface and have a funnel-shaped configuration. Through them, part of the solar wind from the dayside penetrates into the magnetosphere and then into the upper atmosphere. During magnetic storms, particles from the tail of the magnetosphere rush here, reaching the boundaries of the upper atmosphere in the high latitudes of the Northern and Southern Hemispheres. It is these charged particles that cause the auroras here.
So, magnetic storms and daily changes in the magnetic field are explained, as we have already found out, by solar radiation. But what is the main reason that creates the permanent magnetism of the Earth? Theoretically, it was possible to prove that 99% of the Earth’s magnetic field is caused by sources hidden inside the planet. The main magnetic field is caused by sources located in the depths of the Earth. They can be roughly divided into two groups. The main part of them is associated with processes in the earth's core, where, due to continuous and regular movements of electrically conductive matter, a system of electric currents is created. The other is due to the fact that the rocks of the earth’s crust, when magnetized by the main electric field (the field of the core), create their own magnetic field, which is summed with the magnetic field of the core.
In addition to the magnetic field around the Earth, there are other fields: a) gravitational; b) electric; c) thermal.
Gravitational field The earth is called the gravity field. It is directed along a plumb line perpendicular to the surface of the geoid. If the Earth had the shape of an ellipsoid of revolution and masses were evenly distributed in it, then it would have a normal gravitational field. The difference between the intensity of the real gravitational field and the theoretical one is a gravity anomaly. Different material composition and density of rocks cause these anomalies. But other reasons are also possible. They can be explained by the following process - the equilibrium of the solid and relatively light earth's crust on the heavier upper mantle, where the pressure of the overlying layers is equalized. These currents cause tectonic deformations, the movement of lithospheric plates and thereby create the macrorelief of the Earth. Gravity holds the atmosphere, hydrosphere, people, animals on Earth. Gravity must be taken into account when studying processes in the geographic envelope. The term " geotropism" are the growth movements of plant organs, which, under the influence of the force of gravity, always ensure the vertical direction of growth of the primary root perpendicular to the surface of the Earth. Gravity biology uses plants as experimental subjects.
If gravity is not taken into account, it is impossible to calculate the initial data for launching rockets and spacecraft, to carry out gravimetric exploration of ore deposits, and, finally, the further development of astronomy, physics and other sciences is impossible.
