ever thinner layers: a nonlinear process generating ever smaller scales. From the spectral point of view, a power law distribution of energy as a function of scale is expected, even though the kinetic energy is much smaller than the magnetic energy. The last two statements are clear indications that the word turbulence provides a correct description of the dynamical process.

A final important issue is whether the overall dissipated power tends to a finite value as the resistivity and viscosity of the coronal plasma become arbitrarily small. That this must be the case is easy to understand (see § \[sec:eod\]). For suppose that for an arbitrary, continuous, foot-point displacement the coronal field were only to map the foot-point motion, and that there were no non-linear interactions, i.e. the Lorentz force and convective derivatives were negligible everywhere. In this case, the magnetic field and the currents in the corona would then grow linearly in time, until the coronal dissipation at the scale of photospheric motions balanced the forcing. The amplitudes of the coronal fields and currents would then be inversely proportional to resistivity (eqs. (\[eq:bdiff\])-(\[eq:jdiff\])), and the dissipated power, product of resistivity and square of the current, would also scale as 