Hyperspectral measurements of infrared radiance covering the range from 790 to 1250 wavenumbers contain information on the abundance, size and shape of ice crystals in ice clouds. Recent advances in cloud radiative transfer modeling, and in hyperspectral retrieval techniques, now allow for the possibility of deriving cloud optical thickness and effective particle size from such measurements. A significant climate study application of this new capability is assessing the impacts of cloud properties on the Earth's radiation budget through feedback mechanism and radiative forcing.

This paper reviews, briefly, 1) forward scattering and radiative transfer modeling, 2) single-scattering properties of ice clouds, 3) simulation of infrared cloudy radiances, 4) measurements effects of ice crystal habits, 5) impact of the assumption of Henyey-Greenstein phase function, 6) effect on cloud property retrieval of knowledge of surface and cloud temperature, and of atmospheric profile, and 7) cloud property retrieval approach. Retrieval results from SUCCESS and FIRE-ACE field measurements are also presented as case studies.