Temporal evolution of the emerging magnetic dipole. Background images have been taken in the TRACE 1216 Å channel. The superimposed contours represent the magnetic signal detected in the SoHO/MDI data. The magnetic-field contours are plotted at ±25, ±40, ±55 and ±70 Mx cm^-2 with red (blue) contours referring to positive (negative) magnetic polarity. The yellow contours mark the pixels that were used for calculating the magnetic flux density and the total magnetic flux at the footpoints of the emerging loop. The recording time of the particular 1216 Å images is presented in the upper right corner of each subpanel. The corresponding magnetograms are almost co-temporal (with a maximal time difference <30 s). (This figure is available in color in electronic form.)