"The magnetic field is generated by electric currents due to the motion of convection currents of a mixture of molten iron and nickel in Earth's outer core..."
Study of the Earth’s magnetic field and its effects on geophysical phenomena, including the orientation of rocks and minerals and the generation of auroras.
Magnetic field: The concept of a magnetic field and its properties is crucial to understanding magnetism in geophysics.
Magnetic induction: The process by which a material becomes magnetized due to the presence of a magnetic field.
Magnetic susceptibility: A measure of how easily a material becomes magnetized in the presence of a magnetic field.
Remanent magnetization: The permanent magnetization of a material that persists even after the magnetic field causing it is removed.
Magnetic anomalies: Deviations from the expected magnetic field due to variations in magnetic properties of rocks in the subsurface. These anomalies can be used to investigate the geology of an area.
Paleomagnetism: The study of the magnetization of rocks and sediments that were formed at previous times in Earth's history. This can be used to reconstruct the past positions of the continents and other tectonic events.
Thermo-remanent magnetization: Magnetization that is acquired by a material through heating and cooling in the presence of a magnetic field.
Hysteresis: The phenomenon where the magnetization of a material lags behind changes in the magnetic field, leading to a hysteresis loop that can be used to study the magnetic properties of materials.
Magnetotellurics: A geophysical exploration method that uses variations in the Earth's natural electromagnetic field to investigate the subsurface conductivity structure.
Magnetic dipole: A fundamental unit used to describe magnetic fields and magnetic charges.
Magnetic declination: The angle between magnetic north and true north at a particular location.
Magnetic inclination: The angle between the magnetic field lines and the horizontal at a particular location, which can be used to infer the latitude of the location.
Magnetic moment: The strength and orientation of a magnetic dipole.
Magnetic field strength: The magnitude of the magnetic field at a particular location.
Magnetic reversal: An event where Earth's magnetic field reverses polarity, so that the north and south magnetic poles switch places. These reversals occur periodically over millions of years.
Diamagnetism: This type of magnetism is exhibited by all materials and opposes magnetic fields. Materials that are diamagnetic are repelled by a magnetic field, and have a negative magnetic susceptibility.
Paramagnetism: This type of magnetism is also exhibited by all materials, however, they are attracted to magnetic fields. Materials that are paramagnetic have a positive magnetic susceptibility, and only exhibit magnetic properties when they are exposed to a magnetic field.
Ferromagnetism: Ferromagnetic materials can become permanently magnetized, and they are strongly attracted to magnetic fields. Materials that are ferromagnetic include iron, nickel, and cobalt.
Antiferromagnetism: Antiferromagnetic materials have a net magnetic moment of zero, due to their magnetic lattice structure. They are not magnetic in the traditional sense, as the magnetic moments of neighbouring atoms cancel each other out.
Ferrimagnetism: This type of magnetism is similar to ferromagnetism, however, materials that exhibit ferrimagnetism have a net magnetic moment that is not zero. This is due to asymmetrical arrangements of magnetic sub-lattices.
Superparamagnetism: Superparamagnetic materials are very small ferromagnetic nanoparticles. They have a surface area that is much greater than their volume, and as a result, can rapidly switch their magnetic moment even at room temperature.
Spin glass: Materials that exhibit spin glass magnetism do not have a well-defined structure to their magnetic ordering. Instead, they have a disordered distribution of magnetic moments, leading to randomness in their magnetic properties.
Exchange bias: This occurs in bilayer materials, where the magnetic properties of one layer are coupled to the other layer, leading to a shift in their magnetic properties. The exchange coupling can cause one layer to be pinned, leading to a hysteresis loop shift in the other.
Single molecule magnetism: This type of magnetism takes place in molecules that have a large spin quantum number. The magnetic properties of the molecule are determined by the orientation of the spins of the molecules.
Topological magnetism: Topological states of matter can exhibit unusual magnetic properties. In topological magnetic insulators, the magnetic moments of electrons are protected by the topological properties of the material, leading to robust magnetism.
"The magnitude of Earth's magnetic field at its surface ranges from 25 to 65 μT (0.25 to 0.65 G)."
"As an approximation, it is represented by a field of a magnetic dipole currently tilted at an angle of about 11° with respect to Earth's rotational axis..."
"The North geomagnetic pole was located on Ellesmere Island, Nunavut, Canada."
"While the North and South magnetic poles are usually located near the geographic poles, they slowly and continuously move over geological time scales..."
"...but sufficiently slowly for ordinary compasses to remain useful for navigation."
"These reversals of the geomagnetic poles leave a record in rocks that are of value to paleomagnetists in calculating geomagnetic fields in the past."
"...that are of value to paleomagnetists in calculating geomagnetic fields in the past."
"The magnetosphere is the region above the ionosphere that is defined by the extent of Earth's magnetic field in space."
"It extends several tens of thousands of kilometres into space, protecting Earth from the charged particles of the solar wind and cosmic rays that would otherwise strip away the upper atmosphere..."
"The magnetic field is generated by electric currents due to the motion of convection currents of a mixture of molten iron and nickel in Earth's outer core..."
"...these convection currents are caused by heat escaping from the core, a natural process called a geodynamo."
"...where it interacts with the solar wind, a stream of charged particles emanating from the Sun."
"The North geomagnetic pole actually represents the South pole of Earth's magnetic field..."
"...and conversely, the South geomagnetic pole corresponds to the north pole of Earth's magnetic field..."
"...the north end of a magnet, like a compass needle, points toward Earth's South magnetic field, i.e., the North geomagnetic pole near the Geographic North Pole."
"Such information, in turn, is helpful in studying the motions of continents and ocean floors in the process of plate tectonics."
"The ionosphere is defined by the extent of Earth's magnetic field in space."
"...protecting Earth from the charged particles of the solar wind and cosmic rays that would otherwise strip away the upper atmosphere, including the ozone layer..."
"...the ozone layer that protects Earth from harmful ultraviolet radiation."