Geomagnetic field: features, structure, characteristics and history of research

The geomagnetic field (HP) is generated by sources located inside the Earth, as well as in the magnetosphere and ionosphere. It protects the planet and life on it from the harmful effects of cosmic radiation. His presence was observed by everyone who held the compass and saw one end of the arrow pointing to the south and the other to the north. Thanks to the magnetosphere, great discoveries in physics have been made, and so far its availability is used for marine, underwater, aviation and space navigation.

general characteristics

Our planet is a huge magnet. Its northern pole is in the "upper" part of the Earth, not far from the geographical pole, and the south pole is next to the corresponding geographical pole. From these points many thousands of kilometers into the cosmos stretch the magnetic lines of force, which constitute the actual magnetosphere.

Magnetic and geographical poles are sufficiently far from each other. If we draw a clear line between the magnetic poles, we can finally obtain a magnetic axis with an inclination angle of 11.3 ° to the axis of rotation. This value is not constant, and all because the magnetic poles move relative to the surface of the planet, changing their location every year.

Nature of the geomagnetic field

A magnetic screen is generated by electric currents (moving charges), which are produced in an outer liquid core located inside the Earth at a very decent depth. It is a flowing metal, and it moves. This process is called convection. The moving matter of the nucleus forms currents and, as a consequence, magnetic fields.

The magnetic shield reliably protects the Earth from cosmic radiation. Its main source is the solar wind - the movement of ionized particles that flow from the solar corona. The magnetosphere deflects this continuous stream, redirecting it around the Earth, so that hard radiation does not have a harmful effect on all the living blue planets.

If the Earth had no geomagnetic field, then the solar wind would deprive it of its atmosphere. According to one of the hypotheses, this is what happened on Mars. The solar wind is by no means the only threat, since the Sun also releases a large amount of matter and energy in the form of coronal discharges, accompanied by a strong stream of radioactive particles. However, even in these cases, the Earth's magnetic field protects it, diverting these currents from the planet.

The magnetic screen changes its poles approximately once every 250,000 years. The north magnetic pole becomes in place of the northern, and vice versa. Scientists do not have a clear explanation of why this happens.

History of research

The acquaintance of people with the amazing properties of terrestrial magnetism occurred at the dawn of civilization. Already at the time of antiquity, mankind knew the magnetic ironstone - magnetite. However, who and when revealed that natural magnets are equally oriented in space with respect to the geographical poles of the planet is unknown. According to one version, the Chinese were familiar with this phenomenon already in 1100, but it was only two centuries later that it was used in practice. In Western Europe, the magnetic compass began to be used in navigation in 1187.

Structure and characteristics

The magnetic field of the Earth can be divided into:

• The main magnetic field (95%), whose sources are in the outer core of the planet that conducts the electric current;
• An anomalous magnetic field (4%), created by rocks in the upper layer of the Earth with a good magnetic susceptibility (one of the most powerful - the Kursk magnetic anomaly);
• An external magnetic field (also called variable, 1%), associated with solar-terrestrial interactions.

Regular geomagnetic variations

The changes in the geomagnetic field in time under the influence of both internal and external (with respect to the surface of the planet) sources are called magnetic variations. They are characterized by the deviation of the components of the GP from the mean value at the place of observation. Magnetic variations have a continuous reorganization in time, and often such changes are periodic.

Regular variations, repeated daily, are changes in the magnetic field associated with solar and lunar-diurnal changes in the intensity of the GP. Variations reach a maximum in the daytime and in the lunar confrontation.

Irregular geomagnetic variations

These changes arise as a result of the influence of the solar wind on the earth's magnetosphere, changes within the magnetosphere itself and its interaction with the ionized upper atmosphere.

• Twenty-seven-day variations exist as a pattern to the repeated growth of magnetic disturbances every 27 days, corresponding to the period of rotation of the main celestial body relative to the terrestrial observant. This trend is due to the existence of active long-living areas on our native star, observed for several turns. It manifests itself in the form of a 27-day repetition of geomagnetic disturbances and magnetic storms.
• Eleven-year variations are associated with the periodicity of the sun's staining activity. It is revealed that in the years of the greatest accumulation of dark regions on the solar disk, the magnetic activity also reaches its maximum, but the growth of geomagnetic activity lags behind the growth of the solar field on average - per year.
• Seasonal variations have two maxima and two minima corresponding to the periods of the equinoxes and the time of the solstice.
• The age-old, unlike the above, external origin, are formed as a result of the movement of matter and wave processes in the liquid electrically conducting core of the planet and are the main source of information on the electrical conductivity of the lower mantle and core, the physical processes leading to convection of the substance, and also the mechanism Generation of the Earth's geomagnetic field. These are the slowest variations - with periods from several years to a year.

The influence of the magnetic field on the living world

Despite the fact that the magnetic screen can not be seen, the inhabitants of the planet perfectly feel it. For example, migratory birds build their route, focusing on it. Scientists put forward several hypotheses regarding this phenomenon. One of them suggests that the birds perceive it visually. In the eyes of migratory birds, there are special proteins (cryptochromes) that can change their position under the influence of the geomagnetic field. The authors of this hypothesis believe that cryptochromes can act as a compass. However, not only birds, but also sea turtles use a magnetic screen as a GPS-navigator.

The effect of a magnetic shield on a person

The influence of the geomagnetic field on a person is fundamentally different from any other, be it radiation or a dangerous current, since it affects the human body completely.

Scientists believe that the geomagnetic field operates in the ultralow frequency range, which corresponds to the basic physiological rhythms: respiratory, cardiac and brain. A person may not feel anything, but the organism at the same time reacts to it with functional changes in the nervous, cardiovascular systems and brain activity. Psychiatrists for many years have been monitoring the relationship between bursts of intensity of the geomagnetic field and exacerbation of mental illnesses, often leading to suicide.

"Indexing" of geomagnetic activity

Perturbations of the magnetic field associated with changes in the magnetosphere-ionospheric current system are called geomagnetic activity (GA). To determine its level, two indices are used - A and K. The latter shows the value of GA. It is calculated on the basis of measurements of the magnetic screen, carried out daily with a three-hour interval, starting from 00:00 UTC (Universal Coordinated Time). The highest values of the magnetic disturbance are compared with the values of the geomagnetic field of a quiet day for a particular scientific institution, and the maximum values from the observed deviations are taken into account.

On the basis of the data obtained, the K index is calculated. Since it is a quasi-logarithmic quantity (ie, it increases by one when the disturbance is increased by about a factor of 2), it can not be averaged to obtain a long-term historical picture of the state of the geomagnetic field of the planet. For this, there is an index A, representing the daily average. It is defined quite simply - every measurement of the index K is transformed into an equivalent index. The values of K obtained throughout the day are averaged, thanks to which it is possible to obtain the index A, whose value on ordinary days does not exceed the threshold of 100, and in the period of severe magnetic storms it can exceed 200.

Since the perturbations of the geomagnetic field at different points of the planet are not the same, the values of the index A from different scientific sources can vary significantly. In order to avoid such a run-up, the indices A obtained by observatories are reduced to the mean and the global index A _p appears. The same is true for the index K _p , which is a fractional value in the range 0-9. Its value from 0 to 1 indicates that the geomagnetic field is normal, and therefore optimal conditions for passage on short-wave ranges are preserved. Of course, under the condition of a rather intense flux of solar radiation. The geomagnetic field of 2 points is characterized as a moderate magnetic disturbance, which slightly complicates the passage of decimeter waves. Values from 5 to 7 indicate the presence of geomagnetic storms that cause serious interference to the mentioned range, and when a strong storm (8-9 points) makes the passage of short waves impossible.

The effect of magnetic storms on human health

50-70% of the world's population is affected by the negative effects of magnetic storms. At the same time, the beginning of a stress reaction in some people is noted 1-2 days before the magnetic disturbance, when flashes in the sun are observed. Others - at the peak or some time after excessive geomagnetic activity.

People who are meta-dependent, as well as those who suffer from chronic diseases, need to keep track of information about the geomagnetic field for a week, so that if possible, magnetic storms exclude physical and emotional stress, as well as any actions and events that can lead to stress.

Syndrome of deficiency of a magnetic field

The weakening of the geomagnetic field in the premises (hypogeomagnetic field) arises because of the structural features of various structures, wall materials, and also magnetized structures. When in a room with a weakened GP, blood circulation is disturbed, oxygen and nutrients are supplied to tissues and organs. The weakening of the magnetic screen also affects the nervous, cardiovascular, endocrine, respiratory, bone and muscle systems.

The Japanese doctor Nakagawa "called" this phenomenon "a syndrome of human magnetic field deficit". In its importance, this concept can compete with the deficit of vitamins and minerals.

The main symptoms that indicate the presence of this syndrome are:

• Increased fatigue;
• Decrease in working capacity;
• insomnia;
• Headache and joint pain;
• Hypo- and hypertension;
• Malfunctions in the digestive system;
• Disturbances in the work of the cardiovascular system.