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tokens: area enclosed by the dark bubble. Finally, Figure 10 gives an estimate of the order of magnitude of the upflows and also of the delays between them. The upper panel shows Si iv velocities as a function of time for eight pixels within the dark bubble (purple lines). The spatial average of those pixels has been smoothed in time using a five-step running average. This smoothed mean is represented by the black line. For comparison, an average of pixels outside of the flux emergence region is plotted as a cyan line. Note the bump produced in the velocities at around 09:03:00 UT, which is only detected by the pixels belonging to the bubble but not by the pixels outside the magnetic bubble. The bump corresponds to upflows of about 8 km s −1 in the transition region. Note also how some individual pixels within the bubble present transient upflows at other times (e.g., at 08:55:00 UT) that are not captured by the smoothed mean. It is important to realize that the 8 km s −1 upflows found represent the result of a single Gaussian fit to the Si iv spectra. Double Gaussian fits show that the Si iv line is split into two components during the event, as is also evident from Figures 7 and 9 . The more blueshifted component shows velocities of 40–50 km s −1 in bursts, presumably due to reconnection between the emerging bubble and the ambient field (indicating that the bubble has reached the dark appearing canopy of H α fibrils), while the other component is blueshifted by at most a few km s −1 . The Doppler shift derived from the single Gaussian fit of Figure 10 is therefore showing the combined effect of reconnection bursts and the rising bubble, and cannot be considered a real velocity but rather a time marker. Figure 10. Upper panel: Si iv velocities as a function of time for several pixels within the dark bubble (purple lines) and their smoothed mean (black line). Note the bump produced in the velocities at around 09:03:00 UT, marking the existence of an upflow of more than 8 km s −1 in the transition region. Compare to the averaged velocities of pixels outside of the flux emergence region (cyan line). Lower panel: velocities measured in the photosphere (green line and dashed black line), low chromosphere (red line), and transition region (solid black line) as a function of time. Note the successive bumps occuring with a certain delay in the different lines, proving how the upflowing plasma traverses different layers in the solar atmosphere. The Ti ii velocity has been multiplied by 10 for display purposes. The lower panel plots velocities and velocity proxies measured in the photosphere (green and dashed black line), low chromosphere (red line), and transition region (black line) as a function of time. In principle, we would expect that the Fe i intensity darkening and the Ti ii velocity upflow, seen at about 08:55 UT, would occur simultaneously, since both sample the photosphere at similar heights. However, there is a slight delay between the green and