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Earth’s Magnetic Field

The magnetic field of the Earth, also known as the geomagnetic field, is the magnetic field that extends from the Earth's core out into space, where it interacts with the solar wind. The Sun emits a stream of charged particles, which are known as solar wind.

In the Earth’s outer core, electric currents created by the motion of convection currents of a combination of molten iron and nickel are responsible for the generation of the magnetic field. Geodynamo is a natural phenomena that causes convection currents to be produced by heat escaping from the core of the earth. It is responsible for these convection currents.  When seen from space, the magnetosphere is the area above the ionosphere that is defined by the strength of the Earth’s magnetic field. The ozone layer shields the Earth from the destructive effects of UV radiation.  The solar wind is a stream of highly charged particles that originates from the Sun and travels across space. The magnetic field of the Earth deflects the vast majority of the charged particles. In the Van Allen radiation belt, a portion of the solar wind’s charged particles have been trapped for some time. The aurora borealis and geomagnetic storms are caused by the strong solar wind. Auras warm the ionosphere, enabling its plasma to spread into the magnetosphere, increasing the extent of the plasma geosphere. When the solar wind is weak, it is not visible on Earth. Changes in the solar wind have a significant impact on the Earth’s local space environment. Space weather is the term used to describe a collection of these events. It is believed that atmospheric stripping is generated by gas being trapped in magnetic field bubbles, which are then torn away by solar winds.

The Dynamo Effect

The formation of the magnetic field is connected to the rotation of the planet. Venus, with an iron-core composition identical to that of the earth, does not have a detectable magnetosphere. The rotating conductor model gives rise to the terms “dynamo effect” and “geodynamo”.

Representation of the field

Electric and magnetic fields are formed as a result of the basic feature of matter known as electric charge. Two separate parts of the electromagnetic field, which is the force that causes electric charges to interact, are represented by the two fields. An electric field is created by a point charge when it is charged positively and points away from it when it’s charged negatively. A magnetic field is produced by moving charges, which is to say, by an electric current. When a test magnetic pole is brought near to a source of magnetization, the magnetic induction, B, may be described in a similar way to the Lorentz-force equation. F = q(v×B). The right-hand rule describes the direction B by saying that when the thumb points in the direction of the current, B points towards the fingers of the right hand. The angle formed by v and B is known as theta; for a simple line current, the magnetic field is cylindrical around the current. The electric field is measured in the International System of Units (SI) in terms of the rate of change of potential, which is expressed in volts per metre (V/m). Teslas are units of measurement for the strength of magnetic fields (T). The tesla is a big unit of measurement for geophysical studies, therefore a lesser unit of measurement, the nanotesla (nT; one nanotesla = 10-9 tesla), is most often employed instead. A nanotesla is equal to one gamma, a unit of magnetic field initially specified as 10-5 gauss, which is the unit of magnetic field in the centimetre-gram-second system. A nanotesla is also equal to one gamma. Despite the fact that they are no longer recognised as standard units, the gauss and the gamma are nevertheless commonly employed in geomagnetism-related literature. 

The Earth’s Magnetic Field is made up of many components

Earth’s magnetic field is composed of three components that determine its size and direction, as well as its interaction with one another: 
  • Magnetic declination
  • Magnetic inclination or the angle of dip
  • Horizontal component of magnetic field of earth
Magnetic Declination When we talk about magnetic declination, we are referring to the angle formed between the true north and magnetic north. On the horizontal plane, the true north is never in a steady position; rather, it is constantly shifting and changing based on the location on the earth’s surface and the passage of time.  Magnetic Inclination The magnetic inclination is sometimes referred to as the angle of dip in certain circles. Specifically, it is the angle formed by a horizontal plane on the earth’s surface. The angle of dip is zero degrees at the magnetic equator and ninety degrees at the magnetic poles. 

Horizontal Component of the Earth’s Magnetic Field

To understand the strength of the earth’s magnetic field, there are two components to consider: 
  • Vertical component (v)
  • Horizontal component (H)
tanδ=BV/BH sinδ=BV/B cosδ=BH/B sin2δ+cos2δ= BH2/B2+BV2/B2 B=√B2H+B2V

Conclusion

The geomagnetic field is another name for the magnetic field that surrounds the Earth. The earth’s magnetic field stretches millions of kilometres into outer space and has the appearance of a bar magnet, which is a good analogy. Actually, the earth’s south magnetic pole is located close to its northern counterpart while the magnetic north pole is located in Antarctica! This explains why the north pole of a compass magnet truly points north (north and south poles attract). The Earth’s magnetic field reaches far and broad, yet it has a relatively low field strength compared to other planets. A measly 40,000 nT when compared to the strength of a refrigerator magnet, which is ten times stronger.  Convection currents of molten iron and nickel in the earth’s core are responsible for the generation of the planet’s magnetism. Particle streams charged with charges are transported along by these currents, which also produce magnetic fields. These charged particles from the sun (known as solar wind) are redirected away from our atmosphere by the magnetic field, preventing them from entering our atmosphere. Without this magnetic barrier, the solar wind may have steadily destroyed our atmosphere, denying life on Earth the ability to exist in the first place. Mars does not have a robust atmosphere capable of supporting life because it lacks a magnetic field to shield it from the sun’s radiation.
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