A major limitation in accuracy in modern satellite laser ranging is the modeling of atmospheric refraction. Recent improvements in this area include the development of mapping functions to project the atmospheric delay experienced in the zenith direction to a given elevation angle. In this paper, we derive zenith delay models from revised equations for the computation of the refractive index of the atmosphere, valid for a wide spectrum of optical wavelengths. The zenith total delay predicted with these models were tested against ray tracing through radiosonde data from a full year of data, for 180 stations distributed worldwide, and showed sub-millimeter accuracy for wavelengths ranging from 0.355 ¿m to 1.064 ¿m.