Snapshot of NOOA 11024 sunspot at the early stages of penumbra development (08:40:52 UT) as seen in G-band intensity (upper left), LOS velocity (upper right), total magnetic field strength (lower left), and magnetic field inclination in the LRF (lower right). The pink iso-contour outlines the umbral boundary using a threshold of 50% of the quiet-Sun intensity. The three pink boxes in the G-band intensity maps mark the regions studied in detail. The maps have been rotated according to the solar north-south direction. A movie showing the temporal evolution is available online.