Laboratory modeling of increase of the size of the hailstone nuclei

Results over of laboratory modeling of the initial stage of size of hailstone in a wind-channel are presented. Experiments show, that at the rotation of current of air at a speed of 3–4 m/s, at a temperature - 3 $\div$ -7$^\circ$ С and concentrations of crystals a 10$^7$–10$^8$ m$^{-3}$ formation of grit-type hail nuclei of millimetric sizes takes place during a few dozens of seconds.