  We interpret $\gamma$-ray flares from the Crab Nebula as the signature of
turbulence in the pulsar's electromagnetic outflow. Turbulence is triggered
upstream by dynamical instability of the wind's oscillating magnetic field, and
accelerates non-thermal particles. On impacting the wind termination shock,
those particles emit a distinct synchrotron component $F_{\nu,\rm flare}$,
which is constantly modulated by intermittency of the upstream plasma flow.
Flares are observed when the high-energy cutoff of $F_{\nu,\rm flare}$ emerges
above the fast-declining nebular emission around 0.1 - 1 GeV. Simulations
carried out in the force-free electrodynamics approximation predict the striped
wind to become fully turbulent well ahead of the wind termination shock,
provided its terminal Lorentz factor is $\lesssim 10^4$.
