LAUSR

Abstract In this study, the structure and dynamics of tropical cirrus clouds were characterized based on their microphysical properties. The altitude and temperature dependence of the microphysical properties, their interdependence and the most probable shape of the crystals in cirrus clouds were investigated. Studies on the effective size distribution of ice particles, which decides the lifetime of the cirrus clouds is important to understand the radiative properties of the clouds. The small sized crystals having low fall velocities undergo homogeneous nucleation processes resulting in cirrus with longer life time. The microphysical properties of these tropical cirrus, and the role of fall velocity in radiative transfer are discussed from the data obtained using the ground based lidar system over the tropical site Gadanki [13.5° N, 79.2°E], India over a period of 5 years from 2006 to 2010. The CALIPSO satellite based CALIOP lidar observations are used to fortify the ground based observation. It is noted that the life time of the cirrus is enhanced due to the decrease in cloud temperature.