Kolmogorov 1941: turbulent energy injected at large scales cascades to small scales with spectrum E(k) ∝ k^(−5/3) (inertial subrange). Energy dissipation ε = 2ν∫k²E(k)dk occurs at Kolmogorov microscale η = (ν³/ε)^(1/4). The -5/3 line is shown in the spectrum (bottom right).