Ratio between the reflectivity received at vertical polarization, but transmitted with horizontal polarization, and the reflectivity at horizontal polarization. Depolarization of the horizontal polarized pulse is caused by asymmetric particles which are not aligned horizontally. Depolarization of rain is normally very small (app. -40 dB). It is high (-20 to -10 dB) for melting snow and water coated hail or graupel.