Earlier results concerning sympathetic flares and time-correlated rádio bursts are compared with the history and dynamics of development of the magnetic situation in active regions with related flaring. An attempt to present observational evidence of the existence of sympathetic flares is made. We are trying to demonstrate that active regions producing such flares are physically related through common dynamical elements whose magnetic fields display parallel evolution.
The feasibility of using the new photoelectric magnetograph of the Ondřejov Observatory for measuring fast changes in the magnetic
and velocity fields of active regions is considered.
Large line-of-sight motions were found in growing and decaying
sunspots related with areas of magnetic field boundaries and
gradients.
An attempt is presented to explain the large difference in the
intensity, frequency range and number of radio activity events
following the large flares in the two complex active regions of June
1982 (NOAA Nos. 3763 and 3776). The topology of their local magnetic
fields in relation to the global field is discussed as one of the main
factors causing this effect.