Evaporation constants of acoustically levitated drops from the homologue series of n-alkanes and 1-alkanols in ambient air have been evaluated by size and temperature measurements. The size of the pure liquid drops, within a diameter range of 0.1 to 2.5 mm, was monitored using a CCD camera, while temperature measurements were carried out by IR thermography. During drop evaporation, water from a humid environment with a relative humidity between 5 and 80% was condensed on the drop surface and in the case of n-pentane, the condensed water froze as a result of the evaporative cooling.
The formation of ice particles in stationary ultrasonic fields (SUSFs) from ice aerosol was observed. Under suitable experimental conditions aerosol particles gather in stable ellipsoidal systems at temperatures down to <50 K below ambient. We call these systems cold gas traps. The aerosol concentrates in the pressure node areas of the SUSF and conglomerates to form larger particles and snowflakes with diameters up to 10 mm. The resulting shapes are shown. Most of them are similar to those occurring in nature. An attempt is made to explain the effect. Three different processes of ice particle formation are visualized and discussed. Here the existence of a quasiliquid layer (QLL) on the particle surfaces seems to be essential because both the formation of ice particles and the QLL occur only at temperatures higher than about −25 °C. The observed trapping and generation process can be used, for example, in atmospheric physics for the study of particle aggregation, precipitation formation, and water and radiation transport phenomena.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.