Flare evolution from 10 min before the beginning of the impulsive phase to 40 min after the flare in Hα, using a selected area of full disk BBSO images; the green arrows indicate the position of the two main filaments associated to the flare. The boxes in e) and f) indicate areas of increased brightness during the flare impulsive phase (see text). The field of view of the images is 182 × 120 Mm².