Dependence of dust optical depth τ₈₅₇ (left), H i column density N_H i (middle), and H₂ column density N_H2 (right) on dust temperature T_D. The T_D − τ₈₅₇ plot is done for FIR data at the resolution of the 353 GHz data while the other two plots are for FIR data smoothed to the EBHIS resolution. The black contours show the number density distribution of all data points. The blue contour traces the pixels that contain more H i between −20 km s^-1 ≤ v_LSR ≤ +20 km s^-1 than in the IVC range −60 km s^-1 ≤ v_LSR ≤ −20 km s^-1, whereas the red contour traces pixels that have more H i in the IVC regime. In Sect. 4.3 we describe how we derive an H₂ map from the FIR excess emission. Negative N_H2 are a result of the derivation.