Extinction and Liquid Water Content Measurements at CO2 Laser wavelengths

Abstract

Measurements have been made of both extinction coefficients in an evaporating laboratory cloud at wavelength ? = 10.591 ?m using a CO2 laser, and of liquid water content (LWC) at the center of the cloud using a continuous filtration LWC device. Cloud uniformity has been promoted and monitored within the laboratory chamber. The measurements give an overall linear relation between extinction and liquid water content independent of droplet-size distribution in reasonably good agreement with the Ch?lek prediction. The measurements show significantly better agreement with the Ch?lek prediction for the narrower cloud drop-size distributions. The broader size distribution data show an underestimate in extinction compared to the Ch?lek prediction, providing the first experimental evidence for the large radius limit (radius ≤ 12 ?m) in use of the Ch?lek relation.