An analytic model structure for amorphous tetrahedrally coordinated substances is presented. A local coordinate system is attached to each atom in a way that the near neighbors of the central atom occupy approximate lattice positions. The deviations of the atomic positions from the local lattice positions grow with the distance from the central atom. The correlation of the relative orientation of the local coordinate systems is decaying with distance, described by an angular correlation length 1/&THgr;o. The nearest neighbor force constants are taken to be the same for all atoms when expressed in the respective local coordinate system. Using a simple bond polarizability the Raman tensor is calculated. The essential features of the experimental curves, including the &ohgr;4dependence for small &ohgr;, can be reproduced and limiting values for &ohgr; and 1/&THgr;oare found.