Using the three-dimensional hydrodynamical model of the solar atmosphere, we calculated profiles of the Fe I 639.361 nm and Fe II 523.462 nm lines with consideration for deviations from the local thermodynamic equilibrium. We determined heights for in tensity con trast reversal and for velocity sign reversal of convective elements. Both of these parameters depend strongly on the convective velocity and in tensity measured in the continuum. The larger are the parameters, the greater is the atmosphere altitude where the reversal takes place. We compared all the calculated relations with the observations obtained at the German Vacuum Tower Telescope in Izana (Tenerife, Spain). In our opinion, 3D hydrodynamical model of the solar atmosphere describes satisfactorily all the main features of observed convective velocities and intensities.