  We consider triadic nonlinear interaction in the Navier-Stokes equation for
quasi-geostrophic convection in a spherical shell. This approach helps
understanding the origin of kinetic energy transport in the system and the
particular scheme of mode interaction, as well as the locality of the energy
transfer. The peculiarity of convection in the sphere, concerned with
excitation of Rossby waves, is considered. The obtained results are compared
with our previous study in Cartesian geometry.
