University of Toronto experimental physicists are getting closer to understanding why certain icicles form with ripples running up and down their outsides while others form with smooth, slick, equal surfaces.
According to a study that was published in Physical Review E, the researchers found that water impurities become entrapped within icicles as they form and subsequently create chevron patterns that support a ripple effect around their circumferences. The contaminants included sodium chloride (salt), dextrose (sugar), and fluorescent dye.
According to Stephen Morris, a professor emeritus in the Department of Physics in the Faculty of Arts & Science at the University of Toronto and a co-author of the study describing the phenomenon, “Previous theories held that the icicles ripples are the result of surface tension effects in the thin film of water that flows over the ice as it forms.” “We can now observe that surface tension is not necessary for the production of ripples.” “It is tied to patterns of impurities within the ice rather than just being dependent on features outside of the ice.”
“The inside patterns and external shape are different facets of the same problem, which has not yet been described.”
The findings add to an earlier finding by Morris and his research team that the uneven, rippling patterns of icicles developed in the lab were caused by the presence of salt in water. The latest findings demonstrate that the ripples are simply caused by the presence of something alien in the water and not by a specific contaminant.
Lead author of the study and PhD student John Ladan adds, “We investigated numerous species of contaminants, and the phenomena are unchanged as long as their amounts are identical.” This supports the notion that only physical processes—as opposed to chemical ones—are at play.
While the researchers’ interest in understanding natural patterns is their primary driving force, the study of ice growth has important practical implications, such as ice buildup on ships, airplanes, and power lines. The results, for instance, demonstrate that current engineering models of ice accumulation on power lines do not fully capture the issue. The discoveries, according to the researchers, merely add new elements to the phenomenon that must be explained, rather than conclusively explaining the mechanism of the ripples.
According to Morris, “we gain a deeper understanding of the complexity of natural ice formations.”
