  Turbulent relative dispersion is studied theoretically with a focus on the
evolution of probability distribution of the relative separation of two passive
particles. A finite separation speed and a finite correlation of relative
velocity, which are crucial for real turbulence, are implemented to a master
equation by multiple-scale consideration. A telegraph equation with
scale-dependent coefficients is derived in the continuous limit. Unlike the
conventional case, the telegraph equation has a similarity solution bounded by
the maximum separation. The evolution is characterized by two parameters: the
strength of persistency of separating motions and the coefficient of the drift
term. These parameters are connected to Richardson's constant and, thus,
expected to be universal. The relationship between the drift term and coherent
structures is discussed for two 2-D turbulences.
