A Dynamical Model of Orographic Rainfall

A dynamical model for orographic rainfall with particular reference to the Western Ghats is presented. The model assumes a saturated atmosphere with pseudo-adiabatic lapse rate and is based on linearized equations. The rainfall, as computed from the theoretical model, is in good agreement, both in intensity and in distribution, with the observed rainfall on the windward side of the mountain. The model cannot explain the rainfall distribution on the lee side, which apparently is not due to the orography considered in the model. A simple formula for rainfall intensity has also been found based on continuity of mass and continuity of moisture taking into account the convergence or divergence within a thin layer. Further modifications in the dynamical model are also suggested.