The microphysical basis of fog optical characterization

The increasing use by the Army of the various types of electro-optical devices necessitates a test and evaluation program to determine the performance of these devices under a variety of weather conditions, the foggy condition, in particular. The presence of fogs seriously degrades the effectiveness of visible and infrared sensors. It would be impractical as well as uneconomical to test and evaluate each device individually under different atmospheric conditions. A more logical and direct approach would be to characterize and develop physical and optical models of fogs through extensive microphysical, meteorological, and spectral measurements at selected spectral regions, locations, and at different periods of fog evolution. This report presents a brief review of the state of fog microphysics.