From AMS Glossary
(Also called inertial subrange.) The range of length scales over which energy is transferred and dissipation due to molecular viscosity is negligible.
The power spectrum has power law behavior over the inertial range. In two-dimensional turbulence the power spectrum is theoretically proportional to k-3 in which k is the wavenumber, and in three-dimensional turbulence the power spectrum is theoretically proportional to k-5/3. The latter is known as the Kolmogorov minus 5/3 law.