# Dictionary:Poisson reflectivity (PR)

The coefficient of the ${\displaystyle sin^{2}\theta }$ term in the Verm and Hilterman approximation to the Zoeppritz' equations that is used in studies of amplitude variation with offset:
${\displaystyle PR={\frac {\sigma _{2}-\sigma _{1}}{(1-\sigma _{av})^{2}}}}$