Micro-Raman spectroscopic study of extremely large atmospheric ice conglomerations (megacryometeors)

Abstract

For the first time, micro-Raman spectroscopy has been applied to the structural study of four megacryometeors (extremely large atmospheric ice conglomerations that fall in general under blue-sky atmospheric conditions) that fell in Spain. The Raman spectra taken on the megacryometeor cores have been compared with those obtained from an in situ and online study performed on the crystallization process of water in the laboratory. A detailed comparison of the band profiles obtained made it possible to place the formation of the megacryometeors within a particular range of temperatures (−10 to −20°C), which in turn can be related with the altitude of formation in the atmosphere. These results have also been compared with isotope concentrations (δ 18 O and δD) previously obtained in these cores. The two sets of results show a close correlation.