Cartoon 2D representation of the synthetic observations performed in our model. The clouds (blue circles) are distributed throughout the halo (the sphere with radius r_vir), all accreting towards the central galaxy (the central red star) with a radial velocity described by Eq. (12). The vertical gray line represents the line of sight, consistent with the projected distance R of the galaxy from the background quasar, while the area included between the two vertical dashed lines represents the range spanned by the COS-LRG observations. The observer is located at the bottom side of the panel.