elongated structures emanating from the two sunspots (see Fig. \[fig:atmos\_photosphere\]b), similar to large-scale fibrils seen in observations. From now on we call the structures on our synthetic images fibrils too. The fibrils are much more pronounced in [H$\alpha$]{} than in the other lines. The longest fibrils extend up to 35 Mm.

Careful comparison of the panels reveals that the fibrils appear somewhat different in 8542 Å, looking translucent with the background chromosphere shining through. This is especially visible in the upper-right corner. This is consistent with the lower formation height of this line, as discussed in Section \[sec:formation\_height\].

In H$\alpha$, we observe several very bright patches close to the sunspots, which connect with a thinner bright arc. They look similar to flare ribbons. Along these ribbons the [H$\alpha$]{} profiles are in emission and very broad. In [K]{} and [k]{} we see only a weak signature of the ribbon, while in 8542 Å it is only visible as a small brightness enhancement to the right of the upper sunspot.

Now we describe what we see at wavelengths where the intensity in each pixel individually is taken at the wavelength where the formation height is largest. (Fig. \[fig:fig3\_height\], bottom panels). These images 