Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Want ripples on your icicles?

10.10.2013
University of Toronto scientists suggest adding salt

Though it's barely the beginning of autumn, scientists at the University of Toronto are one step closer to explaining why winter's icicles form with Michelin Man-like ripples on their elongated shapes.


This is a natural ripply icicle, collected to measure water composition.

Credit: Stephen Morris

Experimental physicist Stephen Morris and PhD candidate Antony Szu-Han Chen were spurred to investigate by the ripples that appear around the circumference of icicles that occur naturally. It has been theorized that the ripples are the result of surface tension effects in the thin water film that flows over the ice as it forms. Their investigation revealed that the actual culprit is salt.

"Nobody has systematically investigated what causes the ripples so we began growing them in the lab," said Chen, lead author of a paper published online this week in New Journal of Physics. Accounting for key factors that influence the shape of an icicle as it forms in nature – ambient temperature, flow rate of water and the motion of the air surrounding it – the researchers experimented with the composition of the source water.

"We had already tried Toronto tap water and found that it formed ripply laboratory icicles, when distilled water didn't," said Morris. "We also confirmed that melted rippled icicles taken from Toronto garages were very slightly salty, so that's what led us to pursue the composition factor."

Using pure distilled water, distilled water with small quantities of sodium chloride added, and Toronto tap water – which contains sodium chloride as well as many other impurities – they produced 67 samples grown under a broad range of conditions. The evolution of the icicle shapes over time was acquired from digital images using detection of their edges, which were then analyzed with computer image processing.

Ripple growth was not observed on distilled water icicles, whereas saltier icicles showed clear ripples that appear in a patchy way and sometimes grew as large as a few millimetres. The ripples were seen to move slowly upward during the icicle growth, though the researchers note that both the speed and direction of the ripple motion could vary depending on the concentration of dissolved salt.

Morris and Chen found that ripples only became apparent at the remarkably low salinity of the water with 20 mg of salt per litre. This level, in fact, is a considerably lower level of impurity than found in common tap water.

"We even added a non-ionic ingredient to the distilled water to reduce the surface tension of the thin film of water flowing over the icicle, and it didn't produce ripples," said Chen. "Instead, ripples emerge only on icicles grown from water with dissolved ionic impurities."

"Our motivation is pure curiosity about natural patterns, but the study of ice growth has serious applications, including ice accumulation on airplanes, ships and power lines," said Morris. "This result is totally unexpected, not just by us before we did this, but by theorists and experimentalists in our field who study ice dynamics and pattern formation."

"No theory accounts for the effect of salt, so the shape of icicles and the reason for their ripples are still mysteries. Except we now know that a little salt is required in the recipe."

The findings are reported in the paper "On the origin and evolution of icicle ripples". The research is supported by funding from the Natural Sciences and Engineering Research Council of Canada.

Note to media: Contact Sean Bettam at s.bettam@utoronto.ca for images and videos of the research described here.

MEDIA CONTACTS:

Stephen Morris
Department of Physics
University of Toronto
smorris@physics.utoronto.ca
416-978-6810
Antony Szu-Han Chen
Department of Physics
University of Toronto
aschen@physics.utoronto.ca
416-978-0137
Sean Bettam
Communications, Faculty of Arts & Science
University of Toronto
s.bettam@utoronto.ca
416-946-7950

Sean Bettam | EurekAlert!
Further information:
http://www.utoronto.ca

More articles from Physics and Astronomy:

nachricht Igniting a solar flare in the corona with lower-atmosphere kindling
29.03.2017 | New Jersey Institute of Technology

nachricht NASA spacecraft investigate clues in radiation belts
28.03.2017 | NASA/Goddard Space Flight Center

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Researchers shoot for success with simulations of laser pulse-material interactions

29.03.2017 | Materials Sciences

Igniting a solar flare in the corona with lower-atmosphere kindling

29.03.2017 | Physics and Astronomy

As sea level rises, much of Honolulu and Waikiki vulnerable to groundwater inundation

29.03.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>