Given a semi-Riemannian manifold, we give necessary and sufficient conditions for a Riemannian submanifold of arbitrary co-dimension to be umbilical along normal directions. We do that by using the so-called total shear tensor, i.e., the trace-free part of the second fundamental form. We define the shear space and the umbilical space as the spaces generated by the total shear tensor and by the umbilical vector fields, respectively. We show that the sum of their dimensions must equal the co-dimension.2010 Mathematics Subject Classification. 53B25, 53B30, 53B50.