Fig. 1.7 Schematic representation of the advective transport in the case of uniform 1D movement of a fluid with a linear density distribution. The dashed and solid thick lines correspond to the density distribution for the moments of time t0 and t1, respectively. Circles A and B denote the density for two different Lagrangian points passing through an Eulerian observation point (solid rectangle C) at the different moments of time (t0 and t1, respectively).