Freshwater ice can melt into scallops and spikes
Water’s wacky density leads to strange effects that researchers are still uncovering.
Typically, liquids become denser the more they cool. But freshwater is densest at 4° Celsius.
As it cools below that temperature, the water becomes less dense and rises.
As a result, ice columns submerged in liquid water can melt into three different shapes, depending on the water’s temperature, researchers report in the Jan. 28 Physical Review Letters.
“Almost everything” about the findings was surprising, says mathematician Leif Ristroph of New York University.
Ristroph and colleagues anchored ultrapure ice cylinders up to 30 centimeters long in place and submerged them in tanks of water at temperatures from 2° to 10° C.
The ice melted into smooth, downward-pointing spikes if placed in water lower than about 5° C. Simulations showed “a strange thing — that the cold liquid water near the ice is actually buoyant” due to being less dense than the rest of the water in the tank, Ristroph says.
So that upward flow draws warmer water closer to the ice’s base, causing it to melt faster than the top.
The opposite occurred above about 7° C; the ice formed an upward-pointing spike.
That’s because colder water near the ice is denser than the surrounding water and sinks, pulling in warmer water at the top of the ice and causing it to melt faster than the bottom, simulations showed.
This matches “what your intuition would expect,” Ristroph says.
Between about 5° to 7° C, the ice melted into scalloped columns.
“Basically, the water is confused,” Ristroph says, so it forms different layers, some of which tend to rise and others which tend to sink, depending on their density.
Ultimately, the water organizes into “swirls or vortices of fluid that carve the weird ripples into the ice.”
More work is needed to understand the complex interplay of factors that may generate these and other shapes on ice melting in nature (SN: 4/9/21).
See more here: sciencenews.org
Header image: Applied Math Lab/NYU
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Jerry Krause
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Hi James Mc Ginn,,
“Ultimately, the water organizes into “swirls or vortices of fluid that carve the weird ripples into the ice.”
Maybe you can help these mathematician’s out!!!
Have a good day, Jerry
Reply
James McGinn
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Jerry:
Maybe you can help these mathematician’s out!!!
James:
How about this:
Ice Confusion Cleared Up
https://anchor.fm/james-mcginn/episodes/Ice-Confusion-Cleared-Up-e1ekmo4
James McGinn / Genius
Reply
Jerry Krause
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Hi James,
The reason I suggested you might help these mathematicians out was how the water organizes into “swirls or vortices of fluid that carve the weird ripples into the ice.” Because vortices (swirls) is your thing, however I did not hear you mention vortices (swirls) once in your podcast. Hence what you talked about could not help us understand the voices and swirls which carved the ice cylinder in the middle of the image.
Have a good day, Jerry
Reply
James McGinn
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Jerry:
what you talked about could not help us understand the voices and swirls which carved the ice cylinder in the middle of the image.
James:
We have to get the fundamentals right first:
Perfect Circles
https://anchor.fm/james-mcginn/episodes/Perfect-Circles-e1em3db
James McGinn / Genius
Reply
Jerry Krause
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Hi PSI Readers,
Here is another article written by Rachel Cowell (Science News). (https://www.sciencenews.org/article/clouds-wildfire-smoke-rain-climate)
Only because of PSI I discover this source of good information about SCIENCE. Take a look!
Have a good day, Jerry
Reply
Jerry Krause
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Hi James,
Australian PyroCb Smoke Generates Synoptic-Scale Stratospheric Anticyclones
G. P. Kablick III, D. R. Allen, M. D. Fromm, G. E. Nedoluha
First published: 30 May 2020 https://doi.org/10.1029/2020GL088101Citations: 40
SECTIONSPDFPDFTOOLS SHARE
Abstract
Fires in southeastern Australia produced at least 18 pyrocumulonimbus (pyroCb) between 29 December 2019 and 4 January 2020. The largest plumes from this event exhibited several previously undocumented phenomena in the stratosphere. These include (i) the generation of potential vorticity and anticyclonic circulations from absorptive aerosol heating, (ii) the formation of a vertical temperature anomaly dipole, (iii) the rapid ascent from the lowermost stratosphere (15–16 km) to altitudes above 31 km in less than 2 months, (iv) an unprecedented abundance of H2O and CO in the stratosphere, and (v) the displacement of background O3 and N2O from rapid ascent of air from the troposphere and lower stratosphere. Each of these phenomena is traced back to a 5-day-old stratospheric plume composed of a massive amount of aerosol and biomass burning gases from a pyroCb outbreak. Until now, there has been no documented evidence that pyroCb plumes can affect stratospheric winds.
Plain Language Summary
The 2019–2020 bushfire season in Australia has been referred to as the Black Summer by the Australian government due to the extreme amount of destruction it caused. One particularly intense period during this season was between 29 December 2019 and 4 January 2020, when an outbreak of huge thunderstorms fueled by very intense bushfires in southeast Australia emitted unprecedented amounts of smoke to heights 16 km above the surface. Multiple smoke plumes traveled around the Southern Hemisphere over the next few months. One plume (about 1,000 km across and 5 km thick) with very high smoke concentration traveled east from Australia to South America by late January, then reversed course, and completely circled the globe westward over the next few weeks. This plume showed several unusual characteristics, such as excessive lofting from 15 to 30 km due to smoke-induced heating, low ozone, and high nitrous oxide concentrations typical of air at much lower altitudes and winds rotating around the plume at about 15 m s−1. Some of the smaller smoke plumes also showed significant rising and rotation. This is the first evidence of smoke causing changes to winds in the stratosphere and opens up a whole new vein of scientific research.
The complete article can be read. I believe you can get there by following the links in the article to which give it a look.
Have a good day, Jerry
Reply
Jerry Krause
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Hi PSI Readers,
It is not often there is an article posted here at PSI introducing you to an article which has been published in a major science journal such as Physical Review Letters. Which doesn’t allow comments about the articles by people like me for the articles they publish have been peer review by people knowledgeable in the subject matter of the article..
I have contacted Leif Ristroph of New York University and he has sent me a copy of the article. For from what I read here at PSI, I questioned how the cylinder ice was held underwater as the ice melted. For I believe most of us know that ice floats in liquid water.
However, in the complete copy which was published, there is nothing to address the simple question. While I have other questions about what I read in the published article, my sole point here is that the article should not have been published without a description of how the ice cylinders were held in a rigid position underwater as the ice melted. For if another scientist wants to check if this experiment is reproducible this detail needs to be known. As are other details which I can read.
Have a good day, Jerry
Reply
Howdy
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But as you know, and i believe, were getting at, Jerry, asking such questions would throw a spanner in the works and taint the claims, and the peer reviews. Not that peer review actually stands for anything anyway.
Reply