Tag: icicle growth

Growing Flexible Stalactites
Icicles and stalactites grow little by little, each layer a testament to the object’s history. Here, researchers explore a similar phenomenon, grown from a dripping liquid. They’re called “flexicles” in homage to their natural counterparts, and they start from a thin layer of elastomer liquid. Though it begins as a liquid, elastomer solidifies over time.
Timelapse video showing the formation of an initial layer of flexicles from a dripping elastomer.
To form flexicles, the researchers spread a layer of elastomer on an upside-down surface and allow gravity to do its thing (above). Thanks to the Rayleigh-Taylor instability, the dense elastomer forms a pattern of drips that, after hardening, creates a pebbled surface. Subsequent layers of elastomer will drip from the same spots as before, slowly growing longer flexicles (below). The team envisions using them for soft robotics, but, personally, I just really want poke at them and wiggle them. (Image and research credit: B. Venkateswaran et al.; via APS Physics)
A stitched composite photo showing flexicles on a cylinder growing layer by layer.
December 5, 2024
“Winter”
Little by little, snow and ice transform the landscape in Jamie Scott’s film “Winter.” From individual snowflakes to entire forest vistas, the timelapses showcase how winter remakes every surface in its image. The growing icicles show freezing in action, but I especially love seeing the “flow” brought about by progressively greater snowfall. Tree limbs bow, shrubs swell, and riverbanks contract as the snow gets thicker. And that final shot that pulls out from single snowflakes to the entire forest? Stunning! (Video and image credit: J. Scott et al.; via Colossal)
January 26, 2024
Icicles and Impurities
In nature, icicles often form horizontal ripples along their outer surface. Researchers found that these shapes only form when impurities are present in the water forming icicles; icicles made from pure water are smooth. Now researchers are uncovering more details of the ripple formation process, though the underlying mechanism remains unknown.
Icicle using sodium fluorescein as an impurity. a) A vertical cross-section through the icicle shows chevron-like inclusions where impurities are concentrated. b) A similar icicle using salt as the impurity shows a similar pattern. c) A horizontal cross-section through the icicle reveals tree-like rings of concentrated impurities.
Researchers first grew wavy icicles, then melted through them to reveal cross-sections of the icicle. They found chevron-like patterns within the ice, corresponding to areas with higher concentrations of impurities. The team think these chevrons record the process by which flowing water accumulates on the surface of the icicle prior to freezing. (Image credit: top – M. Shturma, cross-sections – J. Ladan and S. Morris; research credit: J. Ladan and S. Morris; via APS Physics)
January 12, 2023
Growing Icicles
For those from colder climates, icicles are a familiar part of winter. They come in a multitude of shapes and sizes, many of which have been captured and cataloged in the Icicle Atlas project. The site contains images, videos, and measurements of more than 230 icicles grown in the lab over the course of four years of research into how and why icicles form the way they do. One interesting result of the work was the discovery that the ripples commonly found on icicles are directly related to impurities. Icicles grown with pure water remain smooth, and only those with ionic impurities, like salt, develop ripples. Check out more images and icicle research at the Atlas. (Video credit: A. Chen and S. Morris/The Icicle Atlas; via Discover)
April 10, 2015
The Evolution of Icicles
The time-lapse video above shows the growth of icicles of various compositions under laboratory conditions. Many icicles in nature exhibit a rippling effect in their shape, which some theories attribute to an effect of lower surface tension in some liquids. Here researchers show the icicle growth of three liquids: pure distilled water, and water with two concentrations of dissolved salt. They found that lowering the surface tension of the freezing liquid with non-ionic surfactants (i.e. not salt) did not produce ripples, but that dissolved ionic impurities like salt strongly affected the growth of ripples. They posit that this may be due to constitutional supercooling, in which growth of the solid-liquid interface is destabilized by the preferential concentration of impurities near the interface. (Video credit: A. S. Chen and S. Morris)
January 23, 2013
Airfoil-shaped Ice
I discovered this interesting bit of icing a couple years ago near the foot of a waterfall in Ithaca, NY. The predominant wind was always heading toward the falls (left to right in these pictures), while the falls were always throwing spray up into the wind. The result was that ice airfoils (center) formed in the wake of each tree branch throughout most of the gorge (top).
February 2, 2011
How to Grow Straight Icicles
New research suggests that icicles grow straighter when exposed to moving air while exposure to still air can cause icicles to sprout at their tips. To grow icicles, the researchers built a refrigerated box that dripped water from the top while the growing icicle rotated. Understanding ice growth is important for flight aerodynamics and icing on airplane wings. For videos and more on icicle growth, see the article at Wired Science. #
August 13, 2010