Dioptrics of the periphery of the eye.

multichromatic wave source so that it was unnecessary for them to invoke eddy viscosity to smear out the critical level singularity which occurs for a monochromatic wave. The depth scale for the critical layer in (3) was determined by the spectral distribution of the IGW's rather than by viscosity as in (1). Since atmospheric IGW's are generally multichromatic, Lindzen and Holton's model is likely the more realistic. Moreover, the assertion by Bekofske and Liu that a decrease of the Richardson number at the critical level allows a larger portion of the wave momentum to pass through without being absorbed is incorrect. It is shown in (4) that if the upward flux of momentum due to the IGW is a constant A far below the critical level, then an amount of momentum given by