  The phenomenology of turbulent relative dispersion is revisited. A heuristic
scenario is proposed, in which pairs of tracers undergo a succession of
independent ballistic separations during time intervals whose lengths
fluctuate. This approach suggests that the logarithm of the distance between
tracers self-averages and performs a continuous-time random walk. This leads to
specific predictions for the probability distribution of separations, that
differ from those obtained using scale-dependent eddy-diffusivity models (e.g.
in the framework of Richardson's approach). Such predictions are tested against
high-resolution simulations and shed new lights on the explosive separation
between tracers.
