Experimental Verification of the Linear Relationship between IR Extinction and Liquid Water Content of Clouds

Abstract

The IR extinction of clouds has been measured with a CO₂ laster transmissometer (λ = 10.6 μm). Using an established linear relationship (based on the Chýlek approximation to the Mie theory) between extinction and liquid water content, the liquid water contents of clouds varying in both droplet size and concentration have been determined. These values are compared with liquid water contents derived from simultaneous cloud collection. The agreement between the two techniques is excellent having a correlation coefficient of 0.98 and corresponding favorable 95% confidence limits. The results indicate that this technique should prove extremely useful for the field measurement of the liquid water content of clouds and fogs.