Examples of the temporal evolution of QSEBs. (a) QSEB first observed in Hβ and then in Hε. (b) QSEB first observed in Hε and then in Hβ. (c) QSEB observed in Hβ alone. (d) QSEB observed in Hε alone. The bottom row of images shows difference (Hε − Ca II H blue wing) images. White shows emission in Hε. Each image is scaled individually. The bottom right panels show a rectangular box along which a space-time diagram along the distance r is shown in the right panels. The yellow arrows indicate the direction toward the limb, so that r = 1 is closer to the limb.