Magnetic dip

Magnetic Dip

Norman Robert dip circle

World Magnetic Inclination 2020

Magnetic dip and shifting in CG

Center of Gravity symbol

Acceleration Error (Northern Hemisphere)

Magnetic dip, also known as magnetic inclination, is the angle made with the horizontal by the Earth's magnetic field lines. This angle varies at different points on the Earth's surface, providing a way to measure latitude using the Earth's magnetism. Magnetic dip is a critical concept in the fields of geophysics, navigation, and compass design.

Overview

Magnetic dip results from the Earth's magnetic field being inclined relative to the Earth's surface. The field is generated by movements within the Earth's outer core, a region of molten iron and nickel. This geodynamo effect leads to a magnetic field that approximates that of a tilted dipole. The angle of dip is 0° at the magnetic equator, where the field lines are parallel to the Earth's surface, and approaches 90° at the magnetic poles, where the field lines are perpendicular to the surface.

Measurement

The measurement of magnetic dip is traditionally done using a dip circle or a magnetometer. A dip circle allows for direct observation of the angle, while modern magnetometers can provide more precise measurements by detecting the strength of the magnetic field in three dimensions.

Importance in Navigation

Historically, understanding magnetic dip was crucial for navigation, especially before the advent of satellite-based systems like GPS. By knowing the magnetic dip, navigators could use the Earth's magnetic field as a reference for determining latitude. This was particularly useful for ocean navigation, where visible landmarks are scarce.

Magnetic Dip Anomalies

Local variations in the Earth's crust can cause anomalies in the magnetic dip. These anomalies are of interest in mineral exploration and archaeology, as they can indicate the presence of ferromagnetic materials underground. Magnetic surveys can map these anomalies, providing valuable data for these fields.

See Also

• Earth's magnetic field
• Geomagnetism
• Magnetometer
• Navigation