Dipole moment

From Glossary of Meteorology

dipole moment

Without qualification usually means electric dipole moment, the product of charge and separation distance of an (electric) dipole.

Dipole moment is a vector, its direction determined by the position vector from the negative to the positive charge. Dipole moments (usually of molecules) are classified as permanent (the centers of positive and negative charge do not coincide even when subjected to no external field) and induced (charge separation is a consequence of an external field acting in opposite directions on positive and negative charges). Water is often given as the prime example of a molecule with a permanent dipole moment. The magnetic dipole moment of a magnetic dipole is the product of the electric current in the loop and the area it encloses. Magnetic dipole moment also is a vector, its direction determined by the normal to the plane of the current loop, the sense of this normal specified by the right-hand rule.