Optical Model of Cirrus Clouds with Preferentially Oriented Particles for Lidar Applications

Abstract

Cirrus clouds are currently under close attention since they play an important role in the formation of the Earth’s climate. They are mainly studied through laser sounding of the atmosphere. The interpretation of laser sounding data requires an adequate optical model of cirrus clouds. However, most existing optical models are developed assuming a random spatial orientation of particles, which, according to recent experimental data, is often inaccurate. We suggest an optical model of cirrus clouds which considers the preferential horizontal orientation of particles within a cloud. The model includes ideal hexagonal plates and columns and hollow columns as quasi-horizontally oriented particles; it additionally incorporates hexagonal plates and columns, droxtalls and bullets, irregularly shaped particles, and aggregates of such particles as randomly oriented particles. The results are crucial for developing lidar data interpretation algorithms for studying cirrus clouds.