(Press-News.org) A group of physicists from Canada have been growing their own icicles in a lab in the hope of solving a mystery that has, up until now, continued to puzzle scientists.
The presence of characteristic ripples along the surface of icicles, which remarkably have the same wavelength no matter how big the icicle or where in the world it grows, have led to several studies examining exactly how the ripples form.
In a new study published today, 10 October, in the Institute of Physics and German Physical Society's New Journal of Physics, the researchers, from the University of Toronto, have proposed that small impurities in the water may be a critical factor in the process.
An analysis of 67 icicles, grown under carefully controlled conditions in a refrigerated box, showed that icicles grown using pure distilled water exhibited no ripples, but those grown from water with salt impurities did have the characteristic ripples.
Furthermore, the ripples grew at a much faster pace, and therefore reached higher amplitudes, when there was a higher concentration of salt in the water. The overall shape of the icicle also became more distorted.
While the research has been motivated purely by the curiosity about patterns in nature, it is possible that a deeper understanding of the formation of icicles may have real world applications, specifically in engineering.
Lead author of the research, Professor Stephen Morris, said: "Ice build-up on structures during freezing rain events is a serious hazard. Power lines, ships, bridges and airplanes must all be protected from, and designed to withstand, ice accumulation. In most engineering applications, only the total amount of ice really matters, not its precise shape. We are interested in the shape, which is much less understood."
There are currently two general theories of why ripples form on icicles, the first of which attributes the formation to the way that heat is removed on the peak of a ripple. It is believed that water freezes more quickly on the peaks because heat is removed quicker from these areas; therefore, any small defect on the icicle can cause ice to build up more quickly in these regions and trigger the formation of ripples.
An alternate theory puts the ripples down to surface tension between the freezing water as it flows in a thin layer over the icicle and the surrounding air – if the surface tension is high, it is predicted that the ripples will grow at a slower pace and reach lower amplitudes.
In their experiments, the researchers carefully controlled the temperature, the flow rate of the water, the composition of the air and the state of its flow around the icicle. The icicles were grown from a wooden support which rotated within the refrigerated box so that the icicles grew evenly and could be imaged from all sides with a camera.
Icicles were grown from pure distilled water, which was then contaminated separately with salt and a surfactant. The researchers also collected melting water from natural icicles on a nearby roof in Toronto and performed a chemical analysis to see if it was sufficiently impure to account for natural ripples – the results showed that it was.
Whilst the presence of salt encouraged the formation of ripples, the researchers also found that the presence of the surfactant, which lowered the surface tension of the water, did not increase the growth rate of ripples, which contradicts one of the previous theories.
"Existing theories of how icicle ripples form have been supported by very few observations of natural or lab-grown icicles. We have performed a really controlled and complete study of icicles ripples that has never been done before.
"Our results have provided strong empirical evidence, but as of yet we don't have a theoretical explanation as to why the impurities have this effect. Neither do we have a theory for why the ripples have a universal wavelength – this still remains a central mystery," continued Professor Morris.
###
From 10 October 2013, this paper can be downloaded from http://iopscience.iop.org/1367-2630/15/10/103012/article
Notes to Editors
Contact
1. For further information, a full draft of the journal paper or to contact one of the researchers, contact IOP Press Officer, Michael Bishop:
Tel: 0117 930 1032
E-mail: Michael.Bishop@iop.org
IOP Publishing Journalist Area
2. The IOP Publishing Journalist Area gives journalists access to embargoed press releases, advanced copies of papers, supplementary images and videos. In addition to this, a weekly news digest is uploaded into the Journalist Area every Friday, highlighting a selection of newsworthy papers set to be published in the following week.
Login details also give free access to IOPscience, IOP Publishing's journal platform.
To apply for a free subscription to this service, please email Michael Bishop, IOP Press Officer, michael.bishop@iop.org, with your name, organisation, address and a preferred username.
On the origin and evolution of icicle ripples
3. The published version of the paper "On the origin and evolution of icicle ripples" Chen et al 2013 New J. Phys. 15 103012 will be freely available online from Thursday 10 October at http://iopscience.iop.org/1367-2630/15/10/103012/article.
New Journal of Physics
4. New Journal of Physics publishes across the whole of physics, encompassing pure, applied, theoretical and experimental research, as well as interdisciplinary topics where physics forms the central theme. All content is permanently free to read and the journal is funded by an article publication charge.
IOP Publishing
5. IOP Publishing provides a range of journals, conference proceedings, magazines, websites, books and other services that enable researchers and research organisations to achieve the biggest impact for their work.
We combine the culture of a global learned society with highly efficient and effective publishing systems and processes. We serve researchers in the physical and related sciences in all parts of the world through our offices in the UK, US, Germany, China and Japan, and staff in many other locations including Mexico and Russia.
IOP Publishing is a wholly owned subsidiary of the Institute of Physics. The Institute is a leading international scientific society with over 55 thousand members promoting physics and bringing physicists together for the benefit of all.
Surplus generated by IOP Publishing is gift aided to the Institute to support science and scientists in both the developed and developing world.
The Institute of Physics
6. The Institute of Physics is a leading scientific society. We are a charitable organisation with a worldwide membership of more than 45,000, working together to advance physics education, research and application. We engage with policymakers and the general public to develop awareness and understanding of the value of physics and, through IOP Publishing, we are world leaders in professional scientific communications. Go to http://www.iop.org
The German Physical Society
7. The German Physical Society (DPG), with a tradition extending back to 1845, is the largest physical society in the world with more than 59,000 members. The DPG sees itself as the forum and mouthpiece for physics and is a non-profit organisation that does not pursue financial interests. It supports the sharing of ideas and thoughts within the scientific community, fosters physics teaching and would also like to open a window to physics for all those with a healthy curiosity.
Water impurities key to an icicle's ripples
2013-10-10
ELSE PRESS RELEASES FROM THIS DATE:
McGill discovery should save wheat farmers millions of dollars
2013-10-10
The global wheat industry sometimes loses as much as $1 billion a year because prolonged rainfall and high humidity contribute to grains germinating before they are fully mature. The result is both a lower yield of wheat and grains of inferior quality. This phenomenon, known as pre-harvest sprouting or PHS, has such important economic repercussions for farmers around the world that scientists have been working on finding a solution to the problem for at least a couple of decades. Their focus has been on genetic factors, and on the interaction between genotypes and the environment ...
First-ever study reveals smell of sweat may alter how women are judged
2013-10-10
(Cincinnati, OH) - Today, a new study from P&G Beauty, the makers of SecretTM deodorants, and lead investigator Pamela Dalton, PhD. MPH, member of the Monell Chemical Senses Center, confirms for the first time that the smell of stress sweat does, in fact, significantly alter how women are perceived by both males and females. Results of the study, published on October 9, 2013 in PLOS ONE, indicate that the odor from stress-related sweat specifically impacts social judgments of one's confidence, trustworthiness and competence.
The ability of human body odor to communicate ...
Want ripples on your icicles? University of Toronto scientists suggest adding salt
2013-10-10
VIDEO:
These are movies of three icicles grown under identical conditions of ambient temperature, water supply rate, and nozzle temperature. (1) was
made with distilled water only; (2) was made with...
Click here for more information.
TORONTO, ON – 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.
Experimental physicist ...
40 years of federal nutrition research fatally flawed
2013-10-10
Four decades of nutrition research funded by the Centers for Disease Control and Prevention (CDC) may be invalid because the method used to collect the data was seriously flawed, according to a new study by the Arnold School of Public Health at the University of South Carolina.
The study, led by Arnold School exercise scientist and epidemiologist Edward Archer, has demonstrated significant limitations in the measurement protocols used in the National Health and Nutrition Examination Survey (NHANES). The findings, published in PLOS ONE (The Public Library of Science), ...
Researchers identify likely causes, treatment strategies for systemic scleroderma
2013-10-10
Using mice, lab-grown cells and clues from a related disorder, Johns Hopkins researchers have greatly increased understanding of the causes of systemic sclerosis, showing that a critical culprit is a defect in the way certain cells communicate with their structural scaffolding. They say the new insights point the way toward potentially developing drugs for the disease, which affects approximately 100,000 people in the United States.
"Until now we've had little insight and no effective treatment strategies for systemic sclerosis, and many patients die within a year of ...
Why we can't accurately judge our friends' behavior
2013-10-10
October 9, 2013 - There is no such thing as objectivity when it comes to your friends: According to a new study, people evaluate their friends' behavior more positively than do strangers, regardless of actual performance on a series of tasks. Researchers say that we should then think twice before allowing people who know each other to be in positions to judge each other – from job interviews to legal settings.
"In judging people we already know, we are more or less unable to ignore our previously established images of those people," says Daniel Leising of Technische ...
Geoscience Currents No. 78
2013-10-10
Alexandria, VA – An important question asked of recent graduates with geoscience majors is why they chose to major in the earth sciences. Recent analysis of over 400 responses from the National Geoscience Student Exit Survey from 71 geoscience departments identified several common answers among the respondents. Of those surveyed, many declared a geoscience major during their formative undergraduate years for a variety of reasons: enjoyment working in the outdoors, a lifelong interest in the subject and desire for career opportunities are among some of the most common.
For ...
Standard, RHDVRT for bladder cancer has comparable tumor control, decreased toxicity
2013-10-10
Fairfax, Va., October 9, 2013—Standard and reduced high-dose volume radiation therapy for muscle-invasive bladder cancer provide comparable tumor control and decreased late toxicity when compared to surgery, according to a study published in the October 1, 2013 print edition of the International Journal of Radiation Oncology ● Biology ● Physics, the official scientific journal of the American Society for Radiation Oncology (ASTRO). The research is part of the United Kingdom's BC2001 clinical trial, one of the largest randomized trials conducted involving radiation ...
CU team finds likely culprit behind liver problems linked to intravenous feeding
2013-10-10
Researchers know that feeding some patients intravenously can save their lives – but also can cause liver damage. Now scientists at the University of Colorado and Children's Hospital Colorado have figured out the likely culprit, one of the ingredients in intravenous food, behind the liver problems.
The discovery, published Oct. 9 in Science Translational Medicine, could point the way to better treatments for patients who are medically vulnerable and, often, very young.
"We still have more to learn about the optimal mix of lipids for intravenous nutrition," said Ron ...
Northwestern researchers develop compact, high-power terahertz source at room temperature
2013-10-10
Terahertz (THz) radiation — radiation in the wavelength range of 30 to 300 microns — is gaining attention due to its applications in security screening, medical and industrial imaging, agricultural inspection, astronomical research, and other areas. Traditional methods of generating terahertz radiation, however, usually involve large and expensive instruments, some of which also require cryogenic cooling. A compact terahertz source — similar to the laser diode found in a DVD player —operating at room temperature with high power has been a dream device in the terahertz community ...