Downloads & Free Reading Options - Results

Laser beam propagation through the earth's atmosphere is influenced by absorption and scattering by ice crystals as occur in cirrus clouds. New instruments (cloudscopes) and laboratory chambers (thermal diffusion, fall tower) have been designed and built to characterize and simulate such crystals to measure absorption and scatter of laser beams. The cloudscope, deployed for aircraft or laboratory use, collects and video-records to crystals to provide a measure of their size, habit, concentration and also density by evaporating the particles after collection. This procedure also reveals their inner structure and the presence of any impurity. These investigations provide protocols for aircraft sampling and analysis of cirrus particles to be analyzed in real-time. This provides input for regional scale models of ice crystal evolution in terms of temperature, supersaturation and fall velocity, resulting in prediction of habits following growth, melt and evaporation and their likely optical properties.