A small magnetic disturbance whose magnetograph resembles an indentation of a coastline. On earth, magnetic bays occur mainly in the polar regions and have duration of a few hours.



Related Terms

UNIVERSAL POLAR STEREOGRAPHIC GRID

A military grid system based on the polar stereographic map projection, applied to maps of the earth’s polar regions north of 84° N and south of 80° S.

PRIME GRID MERIDIAN

The reference meridian of a grid. In polar regions it is usually the 180°-0° geographic meridian, used as the origin for measuring grid longitude.

POLAR MARITIME AIR

An air mass that originates in the polar regions and is then modified by passing over a relatively warm ocean surface. It is characterized by moderately low temperature, moderately high surface specific humidity, and a considerable degree of vertical instability. When the air is colder than the sea surface, it is further characterized by gusts and squalls, showery precipitation, variable sky, and good visibility between showers.

HEELING ERROR

The change in the deviation of a magnetic compass when a craft heels, due to the change i

NORTH GEOMAGNETIC POLE

The geomagnetic pole in the Northern Hemisphere. This term should not be confused with NORTH MAGNETIC POLE.

CROSSED-FIELD DEVICE

Any instrument crossed-needle meter which uses the motion of electrons in perpendicular electric and magnetic fields to generate microwave radiation, either as an amplifier or oscillator.

ACLINIC

Without magnetic dip

IONOSPHERIC STORM

An ionospheric disturbance characterized by wide variations from normal in the state of the ionosphere, such as turbulence in the F-region, absorption increase, height increase, and ionization density decreases. The effects are most marked in high magnetic latitudes and are associated with abnormal solar activity.

STEREOGRAPHIC MAP PROJECTION

A perspective, conformal, azimuthal map projection in which points on the surface of a sphere or spheroid, such as the earth, are conceived as projected by radial lines from any point on the surface to a plane tangent to the antipode of the point of projection. Circles project as circles except for great circles through the point of tangency, which project as straight lines. The principal navigational use of the projection is for charts of the polar regions. Also called AZlMUTHAL ORTHOMORPHIC MAP PROJECTION.

MAGNETIC COUPLING

A coupling that connects two shafts by means of a magnetic field.

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