The geomagnetic field (GP) is generated by sources located in both the magnetosphere and the ionosphere. It protects the planet and life on it from the harmful effects. Its presence was observed by everyone who held the compass and saw how one end of the arrow points to the south, and the other to the north. Thanks to the magnetosphere, great discoveries in physics were made, and until now its presence is used for marine, underwater, aviation and space navigation.
general characteristics
Our planet is a huge magnet. Its north pole is located in the "upper" part of the Earth, not far from the geographic pole, and its south pole is near the corresponding geographic pole. From these points, magnetic lines of force extend into space for many thousands of kilometers, constituting the magnetosphere itself.
The magnetic and geographic poles are quite distant from each other. If you draw a clear line between the magnetic poles, as a result, you can get a magnetic axis with an angle of inclination 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, annually changing their location.
The nature of the geomagnetic field
The magnetic shield is generated by electric currents (moving charges) that are born in the outer liquid core located inside the Earth at a very decent depth. It's a fluid metal, and it moves. This process is called convection. The moving substance of the nucleus forms currents and, as a consequence, magnetic fields.
The magnetic shield reliably protects the Earth from its main source - the solar wind - the movement of ionized particles flowing from the magnetosphere deflects this continuous flow, redirecting it around the Earth, so that hard radiation does not have a detrimental effect on all life on the blue planet.
If the Earth did not have a geomagnetic field, then the solar wind would deprive it of its atmosphere. According to one hypothesis, this is exactly what happened on Mars. The solar wind is far from the only threat, as the Sun also releases large amounts of matter and energy in the form of coronal ejections, accompanied by a strong stream of radioactive particles. However, in these cases, the Earth's magnetic field protects it by deflecting these currents from the planet.
The magnetic shield reverses its poles approximately once every 250,000 years. The north magnetic pole takes the place of the north, and vice versa. Scientists have no clear explanation why this happens.
Research History
Acquaintance of people with the amazing properties of terrestrial magnetism occurred at the dawn of civilization. Already in antiquity, magnetic iron ore, magnetite, was known to mankind. However, who and when revealed that natural magnets are equally oriented in space in relation to the geographic poles of the planet is unknown. According to one version, the Chinese were already familiar with this phenomenon in 1100, but they began to use it in practice only two centuries later. In Western Europe, the magnetic compass began to be used in navigation in 1187.
Structure and characteristics
The Earth's magnetic field can be divided into:
- the main magnetic field (95%), the sources of which are located in the outer, conductive core of the planet;
- anomalous magnetic field (4%) created by rocks in the upper layer of the Earth with good magnetic susceptibility (one of the most powerful is the Kursk magnetic anomaly);
- external magnetic field (also called variable, 1%) associated with solar-terrestrial interactions.
Regular geomagnetic variations
Changes in the geomagnetic field over time under the influence of both internal and external (in relation to the surface of the planet) sources are called magnetic variations. They are characterized by the deviation of the GP components from the average value at the place of observation. Magnetic variations have a continuous restructuring in time, and often such changes are periodic.
Regular variations that repeat daily are changes in the magnetic field associated with solar- and lunar-diurnal changes in the MS intensity. Variations reach a maximum during the day and at lunar opposition.
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 regularity for the re-growth of magnetic disturbance every 27 days, corresponding to the period of rotation of the main celestial body relative to the earthly observer. This trend is due to the existence of long-lived active regions on our home star, observed during several of its revolutions. It manifests itself in the form of a 27-day recurrence of geomagnetic disturbances and
- Eleven-year variations are associated with the frequency of sunspot-forming activity. It was found that during the years of the greatest accumulation of dark areas on the solar disk, magnetic activity also reaches its maximum, but the growth of geomagnetic activity lags behind the growth of the solar one, on average, by a year.
- Seasonal variations have two maxima and two minima, corresponding to the periods of the equinoxes and the time of the solstice.
- Secular, in contrast to the above, - of external origin, are formed as a result of the movement of matter and wave processes in the liquid electrically conductive core of the planet and are the main source of information about the electrical conductivity of the lower mantle and core, about the physical processes leading to the convection of matter, as well as about the mechanism generation of the Earth's geomagnetic field. These are the slowest variations - with periods ranging from several years to a year.
The influence of the magnetic field on the living world
Despite the fact that the magnetic screen cannot be seen, the inhabitants of the planet feel it perfectly. For example, migratory birds build their route, focusing on it. Scientists put forward several hypotheses regarding this phenomenon. One of them suggests that birds perceive it visually. In the eyes of migratory birds there are special proteins (cryptochromes) that are able to change their position under the influence of the geomagnetic field. The authors of this hypothesis are sure that cryptochromes can act as a compass. However, not only birds, but also sea turtles use the magnetic screen as a GPS navigator.
The impact of a magnetic screen on a person
The influence of the geomagnetic field on a person is fundamentally different from any other, whether it be radiation or a dangerous current, since it affects the human body completely.
Scientists believe that the geomagnetic field operates in an ultra-low frequency range, as a result of which it responds to the main physiological rhythms: respiratory, cardiac and brain. A person may not feel anything, but the body still reacts to it with functional changes in the nervous, cardiovascular systems and brain activity. Psychiatrists have been tracking the relationship between bursts of geomagnetic field intensity and exacerbation of mental illnesses, often leading to suicide, for many years.
"Indexing" geomagnetic activity
Magnetic field disturbances associated with changes in the magnetospheric-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 from magnetic shield measurements taken every day at three-hour intervals, starting at 00:00 UTC (Universal Time Coordinated). The highest indicators of magnetic disturbance are compared with the values of the geomagnetic field of a quiet day for a certain scientific institution, while the maximum values of the observed deviations are taken into account.
Based on the obtained data, the index K is calculated. Due to the fact that it is a quasi-logarithmic value (i.e., it increases by one with an increase in disturbance by about 2 times), it cannot be averaged in order to obtain a long-term historical picture of the state of the planet's geomagnetic field. To do this, there is an index A, which is a daily average. It is determined quite simply - each dimension of the index K is converted into an equivalent index. The K values obtained throughout the day are averaged, thanks to which it is possible to obtain the A index, the value of which on ordinary days does not exceed the threshold of 100, and during the period of the most serious magnetic storms it can exceed 200.
Since the disturbances of the geomagnetic field at different points of the planet manifest themselves differently, the values of the A index from different scientific sources can differ markedly. In order to avoid such a run-up, the indices A obtained by the observatories are reduced to the average and the global index A p appears. The same is true for the K p index, which is a fractional value in the range 0-9. Its value from 0 to 1 indicates that the geomagnetic field is normal, which means that optimal conditions for passing in the shortwave bands are preserved. Of course, subject to a fairly intense flow of solar radiation. A 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 create serious interference with the mentioned range, and with a strong storm (8-9 points) make the passage of short waves impossible.
Impact of magnetic storms on human health
The negative effects of magnetic storms affect 50-70% of the world's population. At the same time, the onset of a stress reaction in some people is noted 1-2 days before a magnetic disturbance, when solar flares are observed. For others - at the very peak or some time after excessive geomagnetic activity.
Metoaddicts, as well as those who suffer from chronic diseases, need to track information about the geomagnetic field for a week in order to exclude physical and emotional stress, as well as any actions and events that can lead to stress, if magnetic storms are approaching.
Magnetic field deficiency syndrome
The weakening of the geomagnetic field in the premises (hypogeomagnetic field) occurs due to the design features of various buildings, wall materials, as well as magnetized structures. When you are in a room with a weakened GP, blood circulation is disturbed, the supply of oxygen and nutrients to tissues and organs. The weakening of the magnetic shield also affects the nervous, cardiovascular, endocrine, respiratory, skeletal and muscular systems.
The Japanese doctor Nakagawa called this phenomenon "human magnetic field deficiency syndrome." In its significance, this concept may well compete with a deficiency of vitamins and minerals.
The main symptoms indicating the presence of this syndrome are:
- increased fatigue;
- decrease in working capacity;
- insomnia;
- headache and joint pain;
- hypo- and hypertension;
- disruptions in the digestive system;
- disorders in the work of the cardiovascular system.
Forecast of magnetic storms on the Sun online
Scheme of the formation of a magnetic storm
The graph below shows the geomagnetic disturbance index. This index determines the level of magnetic storms.
The larger it is, the stronger the disturbance. The graph is updated automatically every 15 minutes. Time is Moscow
Kp< 2 - спокойное;
Kp = 2, 3 - weakly perturbed;
Kp = 4 - perturbed;
Kp = 5, 6 - magnetic storm;
Magnetic storm level G1 (weak) from 06:00 to 09:00 Moscow time
Magnetic storm level G1 (weak) from 09:00 to 12:00 Moscow time
A magnetic storm is a disturbance in the magnetic field of our planet. This natural phenomenon usually lasts from several hours to a day or more.
Map of auroral visibility latitudes versus Kp index
Where can you see the aurora now?
You can watch the aurora borealis online here
Forecast of magnetic storms for 27 days
From March 28, 2017 to April 23, 2017, the following magnetic storms and magnetospheric disturbances are possible:
Planetary K-index
Now: Kp= 5 storm
24-hr max: Kp= 5 storm
Auroras Taken by Sacha Layos on March 26, 2017 @ Fairbanks, AK
SUNSPOT GENESIS: A large sunspot is growing in the sun "s northern hemisphere. Only 24 hours ago it didn't exist, now the active region sprawls across more than 70,000 km of solar "terrain" and contains at least two dark cores as large as Earth. Watch this movie of sunspot genesis. http://spaceweather.com/images2017/26mar17/genesis...SID=15h6i0skvioc83feg5delj5a45
speed: 535.4 km/sec
density: 25.2 protons/cm3
POTENT CORONAL HOLE FACES EARTH!!!
A fast-moving stream of solar wind flowing from the indicated coronal hole could reach Earth as early as March 27th (although the 28th is more likely).
This is a "coronal hole" (CH) -- a vast region where the sun's magnetic field opens up and allows solar wind to escape. A gaseous stream flowing from this coronal hole is expected to reach our planet on during the late hours of March 27th and could spark moderately-strong G2-class geomagnetic storms around the poles on March 28th or 29th.
We "ve seen this coronal hole before. In early March, it lashed Earth"s magnetic field with a fast-moving stream that sparked several consecutive days of intense auroras around the poles. The coronal hole is potent because it is spewing solar wind threaded with "negative polarity" magnetic fields. Such fields do a good job connecting to Earth's magnetosphere and energizing geomagnetic storms.
Promising start, right? Admire!
Auroras Taken by B.Art Braafhart on March 27, 2017 @ Salla, Finnish Lapland
Aurora Taken by John Dean on March 27, 2017 @ Nome, Alaska