# Dictionary:Fig T-13

FIG. T-13.
**Transverse isotropy**. **(a)** Wavefront with vertical axis of symmetry (TIV); **(b)** with horizontal symmetry axis (TIH) leading to azimuthal anisotropy; **(c)** phase (wavefront) angle θ and group (ray) angle * for transverse isotropy; (d) elliptical wavefront where ε=–δ; in this case *V

*V*

_{NMO}>*V*

_{vertical};**(e)**anisotropic wavefront where ε=δ; in this case*V*

_{NMO}<

_{vertical};**(f)**wavefront for tilted symmetry axis;**(g)**wave equations for transverse isotropy.