The magnetic elements that determine the Earth’s magnetic field at a point are:
1) Magnetic Dipole Moment: The Earth can be approximated as a magnetic dipole, with a magnetic north pole near the geographic south pole and a magnetic south pole near the geographic north pole. The strength of this dipole moment determines the overall intensity of the Earth’s magnetic field.
2) Magnetic Inclination or Dip: It refers to the angle between the direction of the Earth’s magnetic field lines and the horizontal plane at a specific location. The inclination varies with latitude, with the field lines being vertical at the magnetic poles and horizontal at the equator.
3) Magnetic Declination or Variation: It represents the angle between true north (geographic north) and magnetic north at a given location. Magnetic declination varies from place to place due to variations in the Earth’s magnetic field caused by local anomalies.
4) Magnetic Intensity: Magnetic intensity, also referred to as magnetic field strength or magnetic flux density, measures the strength or magnitude of the Earth’s magnetic field at a specific point. It quantifies how strongly a magnetic field affects a given area or object. The unit of measurement for magnetic intensity is tesla (T) or gauss (G). The Earth’s average magnetic intensity at its surface is approximately 25 to 65 microteslas (µT). However, this value can vary significantly depending on location and geological factors such as local rock composition.
5) Secular Variation: The Earth’s magnetic field is not constant over time but undergoes slow changes known as secular variation. These changes can occur on timescales ranging from years to centuries and are caused by various processes within the Earth’s core.
