Average angular momentum |J/J_th| (solid lines) over gas number density n_g (top left), gas temperature T_g (top right), dust temperature T_d (bottom left), and gas-dust drift ∆s (bottom right), respectively, and typical CNM conditions. All results are for the ensemble of dust grains with a size of a_eff = 400 nm and a fractal dimension D_f = 1.6 (purple), D_f = 2.0 (pink), and D_f = 2.4 (yellow), respectively. The solid lines represent the ensemble average of the angular momenta while the shaded areas indicate the range of one standard deviation of all data points are situated. Dotted lines are the threshold of J/J_th = 3 where a stable alignment is assumed while dashed lines is the average of the corresponding critical angular momentum J = 〈 J_disr〉 where dust grains are estimated to become rotationally disrupted. We note that we plot only the average threshold 〈 J_disr〉 of rotational disruption for clarity while the range of J_disr is about one order of magnitude.