 Abstract A linear relationship, independent of the form of the size-distribution, between extinction at wave-lengths around λ = 00 µm, absorption around λ = 0.0 and 0.0 µm, and liquid water content of atmospheric fogs has been verified using 000 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 CO0 laser (λ = 00.0 µm) transmission along the path, and that liquid water content at a particular point in fog can be inferred from in situ measurement of fog-droplet absorption with a deuterium fluoride laser (λ = 0.0 µm) or a suitably tuned C00 laser (λ = 0.0 µm) spectrophone. Journal: Journal of the Atmospheric Sciences Volume/Issue: Volume 00: Issue 0 DOI: https://doi.org/00.0000/0000-0000(0000)000<0000:VOA