Inversion of rainfall is associated with orographic rainfall.  This occurs due to the ascent of the air forced by the mountain barrier that is across the wind direction so that the moist air is forced in obstruction to move upwards and get cooled. The amount of rainfall increases with increasing height of the barrier such as mountain but this is only up to a certain limit. After that limit, there is a marked decrease due to lesser moisture content of the air and this phenomenon is called Inversion of rainfall.