IFEG   20353
INSTITUTO DE FISICA ENRIQUE GAVIOLA
Unidad Ejecutora - UE
artículos
Título:
Deformations of frozen droplets formed at -40°C
Autor/es:
MARÍA LAURA LÓPEZ; ELDO E. ÁVILA
Revista:
GEOPHYSICAL RESEARCH LETTERS
Editorial:
AMER GEOPHYSICAL UNION
Referencias:
Año: 2012 vol. 39 p. 1805 - 1805
ISSN:
0094-8276
Resumen:
The optical properties of cirrus clouds are frequently computed with respect to various size distributions and ice crystal shapes; in general it is considered that the small ice crystals are quasi-spherical. This approximation can lead to significant errors in the analysis of the in situ microphysical data and also in the theoretical study of the radiative properties of cirrus clouds. Effective size and aspect ratio of the particles are the key parameters required to determine the optical parameters that are included in modeling and prediction of climate; their parameterizations need to be as accurate as possible. In this work, laboratory experiments were conducted to study the ice crystal shape formed from the freezing of water droplets at -40ºC. Liquid and ice clouds were separately formed and sampled in a cloud chamber at -30 and -40ºC, respectively. The water droplet effective diameter ranged from 8 to 20 µm, while the ice particles effective diameter ranged from 8 to 30 µm. The average effective diameters were 11 µm for water drops and 14 µm for frozen droplets. The deformation of the frozen droplets was evident during inspection under microscope; bulges and spikes protuberances were found in many of the observed ice particles. The results show that the aspect ratio of the frozen droplets is 1.2. To our best knowledge, this is the first laboratory work studying the representation of nonspherical ice crystals smaller than 30 mm in diameter.