IFEG   20353
INSTITUTO DE FISICA ENRIQUE GAVIOLA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Laboratory study of the deformation of micrometer-size frozen droplets
Autor/es:
MARÍA LAURA LÓPEZ; ELDO E. ÁVILA
Lugar:
Leipzig
Reunión:
Congreso; 16 International Conference on Clouds and Precipitation; 2012
Resumen:
Cirrus clouds influence the radiative energy budget of the Earth. They mainly consist of nonspherical ice crystals with complicated scattering and absorption features. The characterization of the shape and morphology of ice crystals is important toward the understanding of the optical properties of cirrus clouds.In this work, laboratory experiments were conducted to study the ice crystal shape formed from the freezing of water drops at -40ºC, resembling the conditions that commonly ocurr in the anvil cirrus clouds. The shapes of ice crystals 8-30 mm in effective diameter were observed and compared to those of water drops at -30ºC. Shattered fragments were not observed at any temperature but ice crystals with different kind of protrusions were found. Aspect ratio was calculated to characterize the deformation when water drops freeze. The average and standard deviation values of the aspect ratio were 1.06 and 0.04, and 1.2 and 0.2, for water drops and ice crystals, respectively. The statistical analysis showed that these values were significantly different. However, the aspect ratio showed not dependency with the increasing in the effective diameter, at any temperature. Although bulges and spikes protrusions were found in some of the observed ice crystals, the analysis of the circularity showed that these particles not necessarily lose their circular shape.These results are relevant to the estimation of the optical properties of cirrus clouds and the collection of supercooled droplets by the non-uniform frozen ice particles, with the consequent production of graupel.