  The angle between subsequent particle displacement increments is evaluated as
a function of the timelag in isotropic turbulence. It is shown that the
evolution of this angle contains two well-defined power-laws, reflecting the
multi-scale dynamics of high-Reynolds number turbulence. The proba-bility
density function of the directional change is shown to be self-similar and well
approximated by an analytically derived model assuming Gaussianity and
independence of the velocity and the Lagrangian acceleration.
