Light Attenuation in Falling Snow
ARMY ELECTRONICS RESEARCH AND DEVELOPMENT COMMAND WSMR NM ATMOSPHERIC SCIENCE LAB
Pagination or Media Count:
The effects of snowfall on the transmittance of visible, infrared, and millimeter radiation are assessed on the basis of currently available information. From a tactical applications viewpoint, little information is available for millimeter wavelengths and for the visible and infrared, results vary widely. This variance appears to be real and due to two effects the variety of snow types and the coincidence of fog. Empirical formulae relating transmittance to snowfall intensity are found but are judged to be less useful for tactical purposes than relations to visual range. For the latter, results from different investigators must be combined. Such empirical formulae are thus derived for wavelengths 0.63, 3.5, and 10.6 micrometers and while considerable uncertainty is evident, apparently practical boundaries can be established. Lines of approach for future experimental work are also identified. An increasing number of Army systems rely critically on the propagation of optical energy through the atmosphere. As a result the demand for reliable estimates of optical attenuation in low visibility aerosol conditions is steadily increasing. Among those attenuation least observed or measured is that of snowfall.
- Optical Detection and Detectors
- Infrared Detection and Detectors