Although optical turbulence is usually modeled with micrometeorology, it is shown here that this can be done successfully too with macrometeorology using meteorological parameters measured with standard weather stations and predicted in standard weather forecasts. This makes it possible to predict Cn2 according to weather forecast. Two experimentally derived models are developed--one for practical use and the other for scientific understanding. Correlation of prediction with measurement is on the order of 90% or more, over large dynamic ranges of meteorological parameters. One interesting aspect of these measurements is the statistical evidence that scintillations are affected by aerosols, particularly under conditions of high total aerosol cross-sectional area. Various explanations for effects of aerosols on Cn2 and its measurement are suggested. In addition, validity of the models was examined, and experimental comparisons in two very different climates and surface conditions are presented. High correlation is found in both cases between prediction and measurement.