Flare asymmetry as seen in offband H-alpha filtergrams

Narrow-band H-alpha filtergrams at + or - 1 A and + or - 2 A from the line center were used to study the asymmetry of flares. Of the 60 flares studied, 92% show red asymmetry while 5% show blue asymmetry. Typically, the filtergrams show a striking dominance of the red wing over the blue wing from onset until late in the decay phase. The difference in intensity of the flare emissions is further augmented by the extensiveness of the emission area in the brighter wing. New kernel-like emissions were often found many minutes after the flare maximum. Spatially, they are displaced from the previous kernels. The late emissions show the same asymmetry as that of the earlier part of the flare.