images in Fig. \[fig:fig3\_height\] show long fibrils that follow the large-scale structure of the field. We investigated whether the fibrils trace the magnetic field, both the vertical and horizontal components.

Figure \[fig:overview\_azimuth\] shows the line-core intensity of [H$\alpha$]{}, with the horizontal component of the magnetic field at the formation height overplotted. The fibrils follow the horizontal magnetic field direction in most places, but at some locations (such as the arrow at $(X, Y) = (54, 34)$ Mm) they do not.

Figure \[fig:fibrils\] illustrates the magnetic field component in the plane of a model atmosphere slice that follows the blue line in Fig. \[fig:overview\_azimuth\]. [As expected for active regions,]{} the magnetic pressure exceeds the gas pressure at low heights in the atmosphere, as illustrated by the plasma $\beta = 1 = P_\text{gas} / P_\text{B}$ curve, which goes from $-$1 Mm to $0.5$ Mm. The lowest height of $\beta = 1$ curve is located at the sunspot ($X > 69$ Mm), where the magnetic field strength reaches 6 kG in the photosphere. Horizontally the fibril spans from $X = 51$ Mm to $X = 68$ Mm and for $X < 51$ Mm the cut intersects an area of the atmosphere that shows 