EUV observations of the sunspot. Each column corresponds to a different AIA filter (from left to right: 171 Å, 193 Å, and 304 Å). Rows represent different times, with the time indicated at the left-hand side. Black and white lines illustrate the umbra and penumbra boundaries as selected from contours of constant intensity in AIA 1700 Å. The dotted blue line traces the coronal loop illustrated in Fig. 8. The white square delimits the region used for the average plotted in Fig. 9.