Dependence between EW(Mg II) and local cloud density, n_H, BLR radius, R_in, and the hydrogen column, N_H, with respect to the fiducial values 10¹¹ cm^-3, 10¹⁸ cm, and 10²³ cm^-2 obtained with CLOUDY for the broad band continuum from Fig. 2, for four values of the turbulent velocity (10 km s^-1, blue, 100 km s^-1, red, 500 km s^-1, magenta, 1000 km s^-1, black), and three values of the covering factor (1.0, circles; 0.3, triangles; 0.1, squares). Dashed horizontal lines mark the minimum and the maximum value from Table 4.