Waves propagating through random media undergo large phase and amplitude scintillations even when the scattering at other than very small angles is insignificant. A large number of literature on the subject has been written in recent years. Nevertheless many of the more interesting effects (amplitude scintillation) are not well understood because the theory of the interaction is formulated too abstractly to give insight. The purpose of this work is to provide a phenomenological model with which we derive most of the known expressions-and some new ones-by means of back-of-the-envelope calculations. The model appears to give the needed insights.