  Investigation of the turbulent properties of solar convection is extremely
important for understanding the multi-scale dynamics observed on the solar
surface. In particular, recent high-resolution observations have revealed
ubiquitous vortical structures, and numerical simulations have demonstrated
links between vortex tube dynamics and magnetic field organization and have
shown the importance of vortex tube interactions in the mechanisms of acoustic
wave excitation on the Sun. In this paper we investigate the mechanisms of the
formation of vortex tubes in highly-turbulent convective flows near the solar
surface by using realistic radiative hydrodynamic LES simulations. Analysis of
data from the simulations indicates two basic processes of vortex tube
formation: 1) development of small-scale convective instability inside
convective granules, and 2) a Kelvin-Helmholtz type instability of shearing
flows in intergranular lanes. Our analysis shows that vortex stretching during
these processes is a primary source of generation of small-scale vorticity on
the Sun.
