Abstract
The infrared transmissions from 0.48 to 12.0 μ of various cloud types, including cirrus, cirrostratus, altocumulus, altostratus, and cumulus are reported. The measurements were made using the sun as a source and directing the sunlight into a Perkin-Elmer infrared spectrometer. The transmission is consistently slightly higher in the 8.0- to 12.0-μ region than in the 0.48- to 5.0-μ region. Calculations of the scattering coefficient for nonabsorbing spheres having the density and distribution of droplets found in clouds showed better transmission at the shorter wavelengths than at the longer wavelengths. The difference between this and observation would appear to be due to the influence of the many water vapor absorption bands occurring in the near infrared. A possibility is given for distinguishing between ice crystal and water droplet clouds by means of the behavior of 1.82-μ absorption band.
© 1960 Optical Society of America
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