High resolution {OV5) two-dimensional spectra performed with the Multichannel Soustractive Double Pass (MSDP) spectrograph of the Pie du Midi Observatory, were analysed. An adapted image processing provides two-dimensional intensity and velocity maps of the solar granulation at two intensity levels of the photospheric line NaD2, filtered for the 5 min oscillations. An inspection of such
maps confirms that the bright granules at the continuum level are well correlated witli rising material as well as the dark intergranular spaces with falling material, and that the velocity fluctuations
penetrate much high into the photosphere than the intensity fluctuations. The one-dimensional power spectrum has a slope close to - 5/3, characteristic of a turbulent medium, in the size range
of the granulation. It is suggested that the convectivc energy is supplied by the mesogranulation and the supergranulation; this energy is then cascading toward the smaller scales through the granulation, which thus appears to be turbulent.
The model for deducing the local value of galactocentric gradient of the velociy dispersion is based on the local distribution of the orbital eccentricity e, the mean orbital radius ω and the velocity perpendicular to the galactic plane. We apply it to samples of the Gliese´s catalogue delimited by stars of F,. Gand K spectral types. We obtain for the galactic radial gradient of velocity disperion: -0,2 kpc-1, a value compatible with the Toomre´s local stability criterion.