Ice Formations with Daily (Diurnal) Freeze/Thaw Cycles 

Dr. James R. Carter, Professor Emeritus

Geography-Geology Department

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. 

The photo to the right shows plants of Verbesina virginica with green leaves as of October 28, 2008.  The tallest plant is about 3 feet, or 1 meter, tall.  To the front one can see that a few of the stems had been cut off and thus are not covered over by leaves.

On this morning ice had formed on two of the cutoff stems and there was dew on the nearby grass. The fact that the only ice this day was on these two stems and a nearby car window tells about the process of ice formation in this micrometeorological environment. 

Figure 2 -- 4 cm long ribbon of ice on a cut-off stem of Verbesina virginica , October 28, 2008, in my yard in central Illinois, USA


Figure 1 - Cluster of Verbesina virginica in my yard.  The two white clumps in the lower left corner of the photo are small ribbons of ice, one of which is shown in Figure 2.

In the lower left corner of the photo above are two white objects.  The larger of the two is shown to the left, being a lacy ribbon of ice about 4 cm long growing out from the stem. 

Thus, the relatively warm ground kept ice from forming there, the big leaves on the stems kept the lower stems from cooling by radiating to the clear sky.  But, these two little cutoff stems had just the right conditions to permit ice to form on them.  We will see more ice formations of this nature later.

Within this local air/surface interface many interesting things can happen.  On a visit to Salar del Huasco in northern Chile on a warm, sunny morning I found ice remaining from the night before.  The photo below shows the Salar about 3,780 m elevation at 20.3 degrees S latitude.  In the photo to the right a colleague is dressed comfortably.  Below her left knee is a coin placed on the ice to show the presence of that solid surface. 

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.

Figure 3 -- At a very high, arid area, the Salar del Huasco of nothern Chile gets cold at night but warms significantly during the day under the clear skies.  The freeze/thaw process is common in such environments.  A coin can be shown on the ice below the right knee of my colleague above.  The person is dressed appropriately for the relatively warm temperatures of mid-day.  The Salar del Huasco is a unique wildlife sanctuary. 

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. 


Needle Ice

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.

Figure 4 -- Close-up photos of a small piece of silty soil in my yard in central Illinois, USA.  The coin is a Penny showing the bust of Abraham Lincoln.  It is 1.9 cm in diameter.  When the soil is relatively wet and the temperature falls below freezing, needles of ice form on the surface.  Then when the soil warms during the day, the ice melts and the soil becomes mushy.  In some cases this process is repeated day after day if the soil remains wet and the temperatures cycle above and below freezing. 

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. 

Most 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 Virginia where I found fine needles of ice lifting a thin layer of soil.  In the photo below

Figure 5 -- Example of needle ice in a sandy - silty soil in central Virginia, USA.  The fine needles of ice have lifted the entire surface of soil by about 2 cm.  On the right I am holding a piece of surface soil upside down to show the length of the fine needles.  In the photo on the left the dark areas are caverns under the upraised soil surface.  To the left of the left photo, you can see the leaves of a plant.  As the soil surface was pushed up the leaves have been pushed up but the plant is rooted to the ground and it could not be forced up. 


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. 

Figure 6 -- Photo of needle ice in moss covered soil along the Appalachian Trail in Virginia, USA.  Photo by Lon and Susan Rollinson.  The distinct horizonal line half -way up the needles shows these needles formed over two successive nights.  Obviously, it did not become warm enough during the following days to completely melt the ice needles.  As the soil warms during the day, it settles back down leaving a gap between the ice and the top of the soil.  In the cold of the night new needle ice emerges from soil and carrying some soil with it.  It is possible this process might have gone on for another day or two.

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. 

This process of ice growing and partially melting two days in a row was demonstrated in my yard.  A person in Alabama had sent me a few small rocks that supported the growth of ice in his yard.  After finding needle ice in my yard, I put a few of these rocks on top of an area of bare soil to see if ice would grow on those rocks.  To my surprise ice grew from those rocks under the right conditions.  The photo sequence below shows the same rock over two days of growth and melting.

Figure 7 -- Ice that has grown on a small rock observed over a period of 30 hours.  This occurred in the same area shown above with the Penny.  Note how the ice stayed on top of the rock while the soil moves up with freezing and down with melting.


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

I was introduced to the growth of ice when I found these objects on a hike in Tennessee in late December 2003. 

Figure 8 -- Two photos of the first growths of ice I ever saw.  These photos were taken in late December in east Tennessee, USA.  These growths are at least 10 cm in length.  I suspect the ice formations are on stems of Dittany,  Cunila origanoides.  At the time I took the photos I did not appreciate the need to make more observations.

I 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 Tennessee to try to find these again.  I was not able to find the previous site but found similar displays of ice on a different type of plant.  See my Tennessee findings over two years.

Figure 9 -- In December 2004 I found these ribbons of ice in east Tennessee on stems of Frostweed, or White Crownbeard,  Verbesina virginica.  The photo on the right shows how ice grew out perpendicular from the stem.

I 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 Kentucky on a day in which such ice formations were common along the highway and I got many photos. 

Figure 10 -- Ribbons of ice on cut-off stems of White Crownbeard,  Verbesina virginica in northern Kentucky in mid-November 2005.  In my opinion, the beauty of this photo comes from the interplay of the bright white and green on the various shades of brown.  Here the ribbons of ice are quite massive.  Note the fringes of white frost on the edges of some of the leaves.


In the process I gained considerable insights into their formation and form.  Then a few days later I wandered through an area in central Virginia on a cold, frosty morning looking for any evidence of ice.  I found two small ribbons of ice on plant stems along a farm field but intermixed with those ribbons was needle ice pushing a fine layer of soil up by 1 -2 cm.  And there was a rod of ice about 1 cm in diameter and 4 cm long.  I have yet to explain how that was formed, but of course it melted an hour after I found it.  See my Kentucky story which extended into Virginia.

Figure 11 -- Three forms of ice in the area of sandy/silty soil in central Virginia.  On the left is a small ribbon of ice growing from a stem of Dittany, Cunila origanoides.  In this case, the growth of ice has shattered the base of the stem.  In the middle photo, the needle ice has lifted the soil by at least 2 cm.  On the right is a solid rod of ice, perhaps 5 cm in length.  That rod of ice is one of a kind and I cannot explain its existence.

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 .

Figure 12 -- Three images of ice on Verbesina virginica in buckets in my yard.  On the left, November 7, ice extends far up the stems.  In the middle, the ice is quite full on November 23.  By December 4 the ice is smaller and close to the ground, on the right.  Note how the form of the ice changes throughout the season.


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. 

Figure 13 -- Three different forms on ice in my yard in 2008.  The two images to the left are on stems of White Crownbeard, Verbesina virginica in November.  To the left, looking down along the stem ice has grown out to form a scoop.  In the center we see how ice has grown out along the length of the stem but has then fused together to wrap around the stem.  The image on the right is on a stem of Victoria Blue Salvia and formed in late December.  This ice flower measures 5 cm across at the widest.  The two ribbons of ice on the left were somewhat larger.

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

Soon 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 United States, but I have also seen examples from SW England, the Netherlands and northern India. 

In 2006 I received an email from Geoff Gaynor of Wales with photos of ice growing from branches of wood on the ground.  This ice is similar to that from plant stems, but it is distinctly different.  Lawler had entries in his bibliography discussing this form of ice, so I was able to say something about it.  I received permission from Geoff to put his photos on my web site. 

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. 

Soon I received other photos of ice on wood.  This form of ice is more common in Europe, and I have seen examples from Scotland, Sweden and Germany.  Then I received email from a person on the Olympic Peninsula in western Washington State in the USA with beautiful photos of such ice, demonstrating that it is not exclusive to Europe.  This is now known as Haareis in German or Hair Ice in English.

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. 

In early 2008 I received email from Dr. Gerhart Wagner of Switzerland concerning his work on this form of ice.  He has been investigating Haareis for more than three decades and has published on the topic.  His work shows that Hair Ice is related to the presence of a fungus.  

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

Doctor Weather, aka, Dr. Keith Heidorn of Canada has fed me a few contacts about unusual ice formations.  One contact was from Jared Wilson in nearby Missouri in the central USA.   Jared had photos of ice growing from small rocks in his yard.  After marveling at those images, I came across some photos I received two years earlier from Jerry Green in Alabama showing ice growing from rocks.  I corresponded with both of those persons and had them send me examples of the rocks that permit the growth of ice.  I showed those rocks to my geology colleagues, and they told me they look like rocks, probably chert and nothing more.  Then when I found the needle ice in my yard last winter, I put a few of those cherty rocks on the soil to see what would happen during the freeze/thaw cycles in my yard.  To my surprise some of the rocks produced ice, although not as spectacular as in their best photographs.  The photo of the ice cap formed over two days occurred on one of the rocks from Alabama. 

Figure 17 -- Three examples of ice growing from small rocks in the yard of Jerry Green of Alabama, USA.  Relative to the size of the rocks, the ice extends upwards 3 to 6 cm in length.  Photos by Jerry Green.

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.

Figure 18 -- Three examples of ice growing from rocks in the yard of Jared Wilson of Missouri, USA.  Here it is evident the rocks are some form of chert.  The lenght of the growths of ice are 3 cm or longer.  In the photo on the right some residual snow is evident in the foreground and background.  The question to be asked in looking at these photographs is why a few rocks grow ice and others do not.  Photos by Jared Wilson


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  On this page they note such ice spikes are more common using distilled water.  A complementary explanation was published in Scientific American in 2007.

The 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 Kentucky sent me photos asking for an explanation of how this piece of ice formed.  I made many observations of ice forming in pans of many sizes and came up with some suggestions, but they were not an explanation. 

Figure 19 -- Unusual growth of ice in the metal birdbath of Jeffrey Hutton of nothern Kentucky, USA.  This triangular growth of ice measures about 5 cm across.  As illustrated, it consists of three walls and is hollow in the center.  This was observed in March 2007.  Photos by Jeffrey Hutton.


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. 

Figure 20 -- Sheryl Terris of British Columbia, Canada, captured photos of ice being extruded from a steel fence.  Her photo on the left shows a long ribbon of ice that folds back on itself, like ribbons of candy.  Later she sent photos showing the same pattern of ice was produced again.  In an attempt to explain how that ice was extruded from the fence, I experimented with steel pipes.  The middle and right photos are two examples of what I produced.

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   to share your photos of ice of this nature from your early morning outings.



One of the many web pages of Dr. Jim Carter