Photometric light curves show apparent spot concentrations separated by 180 degrees in longitude that are commonly referred to as `active longitudes'. These spot concentrations have been observed to change in strength resulting in the `flip-flop' …
The linear polarization that is caused by scattering processes in the solar atmosphere has been refered to as the ``second solar spectrum'', since it is structurally as rich as the ordinary intensity spectrum but quite different in appearance and …