  The influence of the convective structure of the solar photosphere on the
shifts of spectral lines of iron was studied. Line profiles in the visible and
infrared spectrum were synthesized with the use of 2-D time-dependent
hydrodynamic solar model atmospheres. The dependence of line shifts on
excitation potential, wavelength, and line strength was analyzed, along with
the depression contribution functions. The line shifts were found to depend on
the location of the line formation region in convective cells and the
difference between the line depression contributions from granules and
intergranular lanes. In visible spectrum the weak and moderate lines are formed
deep in the photosphere. Their effective line formation region is located in
the central parts of granules, which make the major contribution to the
absorption of spatially unresolved lines. The cores of strong lines are formed
in upper photospheric layers where is formed reversed granulation due to
convection reversal and physical conditions change drastically there. As a
consequence the depression contributions in the strong line from intergranular
lanes with downflows substantially increase. This accounts for smaller blue
shifts of strong lines. In infrared spectrum the observed decrease in the blue
line shifts is explained by the fact that their effective line formation
regions lie higher in the photosphere and extend much further into the reversed
granulation region due to the line opacity rise with the increase of line
wavelength. Additionally the effective line formation depths of the synthesized
visible and infrared Fe I lines and their dependence on line parameters is
discussed.
