Ice Formations with Daily (Diurnal) Freeze/Thaw Cycles
Dr. James R. Carter, Professor Emeritus
Illinois State University, Normal IL 61790-4400
In the middle latitudes and at higher elevations in the lower latitudes, many places experience diurnal freeze/thaw cycles. These cycles occur when the air temperature is above freezing for a few hours and below freezing for a few hours. Normally, this cycle follows the Sun with the lowest temperatures near sunrise and the warmest temperatures in mid-afternoon. In the middle latitudes the migration of cold and warm fronts may affect the timing of the onset of freezing, such that temperatures may fall below freezing in the afternoon with the advection of cold air, or the advection of warm air may bring thawing temperatures during the night or early in the morning.
When the air temperature falls below freezing items on surfaces may show the effects. We may see frost on surfaces if the relative humidity of the air is appropriate. Or if the surface is wet enough, we may see frozen dew or the formation of ice in standing bodies of water. This air/surface interface is quite complex, reflecting micrometeorological conditions, as illustrated in this case.
At 7:00AM on 28 October the television reported the local air temperature was 28 degrees F (-2.5C) and the Dew Point was 22 degrees F (-5.6C). A mercury thermometer on my deck exposed to the sky read 26 degrees F (-3.3C). It had been a cloudless night with no wind. My boots were wet from the dew on the grass, but I found ice in two places. My neighbor’s car had frost on the windshield and top and there was ice on two small plant stems. See Figures 1 and 2. To get a better measure of this temperature environment, I placed two digital thermometers out, one under a cardboard box next to the ground and one on top of the box exposed only to the clear sky. After a few minutes the one under the cardboard next to the ground read 34.2 degrees F (1.2C) while the exposed one read 27.5 degrees F (-2.5C). Indeed, there was great variation in temperatures in this surface boundary layer for the windshield and car top cooled to the frost point and the stems of two plant which were off the ground were cold enough to produce ice. But the ground was cold enough to have dew deposited but not cold enough to have the moisture deposited as frost.
this local air/surface interface many interesting things can happen. On a visit to Salar
del Huasco in northern
I have read about flamingoes which wade in these lakes being frozen in overnight as ice formed around their legs as they fed in the water. With the heat of the Sun they were freed the next morning.
Solid objects such as soil will experience the freezing temperatures at the surface but with depth the temperatures will be less affected by hour-to-hour changes. It takes time for the heat from within the soil to be lost to a colder surface, and conversely for heat from a warmer surface to penetrate into the soil.
Thus, during these diurnal freeze/thaw cycles the temperature of the air and the near surface falls below freezing while the temperatures a little below the surface of the solid and liquid objects may remain above freezing. Depending on the temperature differences over the period of time, as well as the nature of the surface material, the diurnal depth of freezing will vary from a few millimeters to a few centimeters.
Recently, I observed that some of the areas in my yard crunched underfoot as I walked across the grass early in the morning. That prompted me to look closer and I found many examples of water at the top of the soil being frozen. By contrast, four hours later the soil had warmed and the icy areas were now mud. Again, the next morning there were needles of ice in some intricate patterns, only to turn back to mud in a few hours.
At 9:00AM the top of the soil is made up of needles and blades of ice with crags in between. The coin is standing up between needles of ice. A few hours later the ice has melted and turned to mush and the coin has fallen over.
The diurnal freeze/thaw process in soil is well known and the resulting ice is known as needle ice in English, Kammeis or Stengeleis in German, in Japanese it is Shimobashira, in Spanish Hielo acicular and in Swedish it is Piprakes. Lawler compiled a bibliography of needle ice and lists even more names for this phenomenon. his bibliography includes material from most continents and includes articles dating back to the early 1800s.
of the needle ice that people photograph and report on is more attractive
than the mud in my yard. My first
focus on needle ice was in
In the photo on the right, I am holding a piece of the top layer of soil with the needles sticking up. These needles are about 2 cm in length. On the left you can see the spaces below the top layer of soil from the underlying soil. Note on the left the leaves of the small green plant are bent upwards by the uplifted surface while the center of the plant remains rooted to the ground. Within a few hours those needles would have melted, and the top of the soil would have collapsed back to its original position and the plant would be back on the surface.
Lon and Susan Rollinson of Virginia sent me photos of needle ice they found while hiking along the Appalachian Trail in the Appalachian Mountains. Here the needles of ice are larger and very distinct. In this photo we see that the needles of ice had forced up the overlying mossy surface.
The horizontal band of dirt separating the upper needles from the lower tells us that needles of ice were pushed up two nights before and then partially melted the next day. When that partial melting took place the needles and overlying surface material settled back down. Then with the cold of the next night new needles formed and rose up to touch the needles from the night before. At the time this photo was taken, the dark underlying soil had warmed enough to settle back down but the needles of ice had not yet melted. With the right conditions, this sequence might have continued on for another day or two.
process of ice growing and partially melting two days in a row was
demonstrated in my yard. A person in
On Day 1 (February 28, 2009) at 10AM I had ice on a number of the small rocks and one in particular had a nice cap of ice. By 3PM the soil around the rock had melted and settled down while some of the cap of ice remained. Sub-freezing temperatures at night caused new ice to grow so at 10AM the next morning, Day 2, the new ice was pushing up the cap of ice from the previous day. By mid-afternoon the horizontal line in the ice cap clearly demonstrates that this ice was formed in two separate stages. In the case of this ice formation, the temperatures remained below freezing for the next three days and that ice cap became smaller day by day before melting under warmer weather.
These two sets of photos demonstrate some effects of freeze/thaw cycles at the surface. To find such examples requires a combination of things. In addition to the diurnal variation in temperatures, you need a medium which accommodates the growth of ice and enough water in and near the medium to support the growth of ice. And to get documentation of such growths of ice you need persons to search for such ice at the right time of day with camera in hand and a willingness to share findings with others.
My introduction to such ice formations
was introduced to the growth of ice when I found these objects on a hike in
had no idea what I had photographed and a few months later posted some photos
on the web to share with a colleague.
When I put them up on the web I searched to see if others knew about
such ice formations. I found a few
sites referring to these as ice flowers, frost flowers or ice ribbons. I linked my pages to those pages. The next year I went back to
searched through fields and forests trying to find plants that
might grow such ice. The problem is
being in the right place at the right time to find these ice formations. In 2005 I drove through
the process I gained considerable insights into their formation and
form. Then a few days later I wandered
through an area in central
I had looked in libraries and on the web for information about such ice formations and did not have much luck. But, once I found the needle ice in association with ribbons of ice, I had a new term to search on. That new term led me to the extensive bibliography by Lawler with those 267 entries going back to the early 19th Century. Included in those references were articles and letters describing many of these forms of ice. I was beginning to gain an understanding of the nature of the ice formations on plant stems and now had good information on the formation of needle ice in soils.
In fall of 2006 I found a large patch of White Crownbeard, or Frostweed, Verbesina virginica, one of the plants that support the growth of ice flowers. I brought many seeds home and planted them in the spring of 2007 in buckets in my yard. I live about 300 km north of the northern range of this plant, so I was very pleased to find the plants grew in my buckets. With my own plants I did not have to search to find a source for displays of ice on plant stems. And, on 7 November I had ice on many stems of those plants. Based on what I had read, I assumed the ice would shatter the stems of the plants. But, during that fall and winter I had new ice on those stems many times and the stems did not shatter. I did find that early in the season the ice extended from the base up the stem some 20 30 cm. Then, as the plant died and dried up, the ice did not extend as far up the stem. By the end of the season the only ice on the stem was next to the ground. In total, I had ice more than 20 separate times that fall and winter. See the ice story of 2007 in my yard .
While observing ice on the Verbesina virginica in my buckets one morning, my wife saw a patch of ice in her flower garden. Investigating, we found ice on the stems of Salvia, a common garden plant. It was not as impressive as the ice in the buckets, but it showed another plant that supported the growth of ice from the stems. So, next year we planted three varieties of Salvia and found ice on those stems.
In spring 2008 I planted seeds of Verbesina virginica again in the buckets and in other places in the yard. In late October I found my first ice. Throughout that fall and winter I spent many hours photographing ice on Verbesina virginica. View a collection of photos of this ice.
That fall I also had ice on three varieties of Salvia and surprisingly on stems of Vinca. While looking for the ice on these plant stems, I observed the needle ice in the soil that I referenced at the start of this discussion. View a collection of photos of ice on Salvia and Vinca stems .
There are some interesting stories about the discovery of ice growing on plant stems over the past two centuries. And I provide a compilation of all of the plants on which we know ice forms. Check out the page on Ice Formations on Plant Stems .
Ice Growing from Dead Pieces of Wood
after posting my first web pages in 2004, I started to get inquiries from
persons who had taken photos of ice they found and wanted an explanation of
what they had seen. This is a
wonderful way to find ice formations that I could never find on my own. Most of the ice formations on plant stems
are seen in the
2006 I received an email from Geoff Gaynor of
Figure 14 -- Two examples of Hair Ice as captured by Geoff Gaynor in Wales. In the photo on the left the piece of wood lies in a low area surrounded by leaves. Ice seems to be emerging from along the full length of the piece of wood. In the photo on the right it is less clear where the wood is relative to the ice, but this ice has a different texture than the ice seen growing from plant stems.
I received other photos of ice on wood.
This form of ice is more common in Europe, and I have seen examples
Figure 15 -- This photo by bobbi fabellano from the Olympic Peninsula, Washington State, USA, distinctly shows the piece of wood without any bark on it. In the photo the ice seems to wrap around the piece of wood. And it appears that the wood is not lying on the ground.
In the ice ribbons from plant stems, the strands of ice seem to fuse together while in Hair Ice the individual strands of ice do not fuse together to make the same kinds of ribbons. The photo below shows those individuals strands or hairs.
Figure 16 -- In this photo by bobbi fabellano the ice is only on the top of the dead branch of wood, unlike in the previous photo. Note that this branch is well above the ground.
early 2008 I received email from Dr. Gerhart Wagner of
I have yet to see this form of ice because it seems to occur only in western Europe and the Pacific Northwest of North America. It has been associated with five different species of deciduous trees. Check out the web page devoted to many more photos or Hair Ice and the history of the discovery of this product of the diurnal freeze/thaw process on dead wood.
Ice Growing from Small Rocks
Weather, aka, Dr. Keith Heidorn of
While the ice on these rocks from Alabama is impressive, the growths of ice on the rocks from Missouri is even more dramatic. I have personally seen the growth of ice similar to that in the three photos above, but I have not been able to produce anything as dramatic as shown in the photos below.
Recently I published an article in the January/February 2009 issue of Weatherwise entitled: Unusual Ice Formations: Studying the Growths of Ice from Soils, Stems, Branches and Rocks. In this article I argue that this diurnal freeze/thaw process in the surface boundary layer produces some interesting beauties of nature, but the products vary with the media from which they grow. As far as I know this is the first publication relating the growth of ice on these four different media. Supplemental material on that paper .
A Controlled Explanation of these Processes
In addition to all of this, Dr. Charles Knight of the National Center for Atmospheric Research directed me to the article by Ozawa and Kinosite, Segregated Ice Growth on a Microporous Filter Journal of Colloid and Interface Science, (132: 1, 1989). Ice segregation is the term used to describe the process of ice growing out of moist porous material.
Ozawa and Kinosite describe how they grew ice on a micro filter, replicating the process that seems to explain what is happening in these natural situations. They designed their experiment to have super cooled water from below be in contact with a micro filter. The spaces of the microporous filter were large enough to let liquid water pass through but too fine for ice crystals to pass through. When an ice crystal was introduced onto the surface of the micro filter, new ice grew on the surface as the super cooled water from below flowed up through the filter and froze at the base of the ice crystal.
The Challenges Going Forth
What I know about these formations of ice is limited to what I have been able to observe and measure in my own yard, what I have been able to find on occasional trips, the notes and photos that people have sent me, and the few writings that have appeared in literature over the past two centuries. I am certain there is much more to be seen and many more places to be heard from.
I throw the challenge to you to get out on cold mornings to see what you can find. Look at the soil for needle ice, look at small pebbles of rock to see if they are growing ice, look at plant stems to find ribbons or flowers of ice, and look for hair ice, or Haareis, on pieces of wood. But do look up on occasion because there may be Haareis in the trees.
Then when you find an interesting display of ice, take some photos, note where you found it and the conditions, and share this with the rest of us.
Other Unusual Formations of Ice
Be aware that there are other interesting formations of ice on man-made objects. Again, because of the web and digital cameras we have learned about many of these exotic formations of ice.
While trying to understand the behavior of ice formation, I had water in caps of bottles and pans in my yard. I was observing how water froze in various sizes of pans and dishes.
To my surprise, one night at about 11:00PM I found the water in one bottle cap formed into what is called an Ice Spike. I had read about these but suddenly I had my own. I have been able to produce ice spikes on occasion but have not been able to do it consistently.
There are people who grow these regularly. A particularly good web site which explains the process is supported by SnowCrystals.com. On this page they note such ice spikes are more common using distilled water. A complementary explanation was published in Scientific American in 2007.
reason that I was trying to observe the formation of ice in pans is that I
was trying to explain how a hollow wedge of ice formed in a bird bath. Jeff Hutton of
In the March/April 2009 issue of Weatherwise Tom Schlatter shows three photos of this ice and attempts to explain the process. He gives credit to Dr. Charles Knight of the National Center for Atmospheric Research for help in developing his answer. I should note that Dr. Knight has helped me in explaining some of what I have found.
The explanation starts by noting that this happened during a diurnal freeze/thaw time -- above freezing during the day and below at night. And it is likely the surface water was super-cooled. Then when the ice crystallization process started, certain axes were lined up to produce planes of ice needle growth. Schlatter noted that he knows of no studies which explain this process. So, here is another challenge for readers.
This triangular ice in the birdbath is not unique in the world. The Weatherwise explanation provides a link to a web page of a couple in Scotland where they show a number of such ice formations that they found in their garden. And I have received photos from other persons showing triangular wedges of ice growing in bird baths. I appreciate seeing such photos so please share them with me.
Extruding Ice from Steel Structures
In 2007 I received photos from Doctor Weather of ice being extruded from a steel fence in British Columbia, Canada. Sheryl Terris had contacted Dr. Weather and he then sent the photos on to me. I corresponded with her, and she gave me permission to use her photos. Among her photos were some interesting and attractive ice formations and I felt compelled to explain how these formed. I tried many types of pipes and finally succeeded with steel pipes. While I was not able to duplicate the overlapping ribbon of ice from the steel fence, I was able to extrude ice from steel pipes into some interesting forms. I feel I was able to explain the process at work on that steel fence.
I have a page showing more photos of the ice extruded from the fence in Canada and the ice I was able to extrude from steel pipes. I detail the processes I use to grow ribbons of ice through steel pipes, so you can try it yourself.
Then I received an email from Kath in SW England showing ice being extruded from steel support pipes on some metal steps. In this case the ice is extruded as a rod that forms a spiral. A couple of years later I received some photos from Alexander in Moscow, Russia, showing a rod of ice coming out from a steel pipe and forming a spiral, very similar to those observed by Kath in England. In Moscow the pipes from which this ice grew were part of a climbing aparatus for children -- a jungle gym.
In both cases the rods of ice came out of a hole at the top of a pipe. How did the holes get there? Based on my view of the photos, I suspect there is a gap in a weld or a design hole. How did water get in these holes? I suspect it came from rain running around the pipe and just built up over time. And this is consistent with diurnal freeze/thaw processes. See more photos of these spirals.
How exotic is this ice? It is not common but perhaps not all that exotic. Who goes to a playground on a gray day with snow? And, if you were there would you see a small spiral of ice on one post? Once we are introduced to such ice formations, we might find more examples. Please send me any photos you can capture.
My Growing World of Ice Formations
Ten years ago, I knew about icicles and patches of ice on streets and walkways, and that was about it. Now on those days when it is above freezing part of the day and below freezing part of the day, I look for ice in many diverse places, and often find it. In local environments this can be a very dynamic time. I hope you will join me in the search for ice in its many forms on those days.
The ribbons of ice are formed by super cooled water penetrating through the stems of the plant and freezing in the colder air when they encounter an ice crystal. The water continues to move up the stems to feed the growing ribbons of ice. Something similar must happen in dead pieces of wood to create Hair Ice. I have yet to find an explanation as to why a few rocks support the growth of ice and most rocks do not. There is a good literature explaining the formation of Needle Ice in soils.
What we do know is that this ice is not a form of frost. Frost comes about when water vapor in the air becomes saturated and is deposited on a surface as an ice crystal. If the air temperatures are above freezing, we get the formation of dew, but when it is below freezing the moisture is deposited out of the air as frost. In Figure 10 above you can see that frost has been deposited on leaves and blades of grass. Certainly, in most cases the conditions that are appropriate to the growth of ice are also appropriate to the formation of frost. For this reason, some of the older names for the formations of ice on plants are called frost flowers and the plants are called such names as frost weed.
Indeed, there is another world of beauty in the many ways frost forms on surfaces and objects. There are many sites on the web where photographers show their frost pictures.
Thank goodness for the Internet and digital cameras for they let us exchange information about these attractive ice formations. Please take on the task of looking for ice when the freeze/thaw processes are underway. Feel free to contact me at email@example.com to share your photos of ice of this nature from your early morning outings.
One of the many web pages of Dr. Jim Carter