The lines corresponding to Zeeman splitting also exhibit polarization effects. Polarization has to do with the direction in which the electromagnetic fields are vibrating. This in turn, can have an effect on whether the spectral light can be observed. For example, polarizing sunglasses cut the glare from surfaces because light reflected from surfaces has a particular polarization that polarizing sunglasses do not transmit.

One practical example in astronomy of such polarization effects is that in the adjacent diagram the middle transition is polarized such that it cannot be obverved from directly over a surface perpendicular to the magnetic field. As a consequence, usually when looking directly down on a sunspot (which have strong magnetic fields) only two of the three transitions shown above can be seen.