Verification of a linear relation between IR extinction, absorption and liquid water content of fogs.

Abstract

A linear relationship, independant of the form of the size-distribution, between extinction at wave-lengths around lambda = 11 micro m, absorption around lambda = 3.8 and 9.5 micro m, and liquid water content of atmsopheric fogs has been verified using 341 droplet size distribution measurements made under a variety of meteorological conditions. The results suggest that integrated liquid water content along a path in fog can be determined from measurement of CO2 laser (lambda = 10.6 micro m) transmission along the path, and that liquid water content at a particular point in fog can be inferred from in situ measurements of fog-droplet absorption with a deuterium fluoride laser (lambda = 3.8 micro m) or a suitably tuned CO2 laser (lambda = 9.5 micro m) spectrophone. - Authors