Needle Ice Dr. James R. Carter, Professor
Emeritus Illinois State University, Normal IL
61790-4400 |
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Figure 1
- An example of needle ice observed in east Tennessee in December. The
knife is 6 cm long (2.5 inches). Note the individual strands of ice, in
many places fused together. On a few small rocks in this immediate area
unique forms of ice grew atop the rocks forming what is called Pebble Ice. The
occurrence of both forms of ice in the same place shows the close
relationship between Needle Ice and Pebble Ice. In a
process called Ice
Segregation cold water moves through a medium toward the presence of ice,
freezes at the interface and adds to the ice. When this occurs at or near the surface of
soil it produces Needle Ice, which takes the form of strands of ice rising
vertical from the surface or near surface of the soil. When this
same process of Ice Segregation occurs on certain plant stems it
produces Ice Flowers . When it occurs on pieces of dead wood the
resulting ice is called Hair Ice.
When it occurs on some small rocks it forms Pebble Ice. All
of these forms of ice have similarities but are unique. Ice
Segregation is known to occur in subsurface environments and can be a
significant geologic force in areas with permafrost and in periglacial
environments. Nature of Needle Ice Needle
ice is quite common, and many people have encountered it when they walk across
a grassy surface on a cold morning and the ground crunches underfoot. In some cases, it can be quite large or
unique and attract attention. The process of moving soil particles with ice
can disrupt the soil surface and in the process be a factor in shaping the
landscape and eroding the land as well as doing road damage. On occasion it can produce attractive
displays similar to ice flowers and hair ice, but
generally needle ice is destructive and disruptive and not particularly
attractive. Considerable
research has been conducted on needle ice.
Lawler (1988) published a bibliography of Needle Ice listing 267
references dating back to 1824. The
phenomenon occurs in many countries and is known as Kammeis
or Stengeleis in German, Shimobashira
in Japanese, Hielo acicular in Spanish and Piprakes in Swedish.
Lawler provides a table listing the many terms people have given for
this phenomenon. For
Ice Segregation to produce ice, the medium must have enough pore space to
conduct water to the surface to supply the growth of ice, but the pore
spacing must be small enough to hold the water in place against gravity. In general, this spacing exhibits
capillarity which will wick water toward the surface. Meetenmeyer and Zippin (1982) discuss the texture of soils that produce
needle ice, noting that a significant presence of clay and silt are required
in such soils. They were able to ‘create’ soils that grew ice in a refrigerated
environment.
If
you ever had the soil crunch underfoot on a cold morning, then it is likely
you were walking on needle ice. Such
needle ice would not be as impressive as above, but still, it is needle ice. Once
I started looking for ice, I noticed that one area of bare soil had small
ridges and pits on cold, frosty mornings.
These ridges are needles of ice. This area of bare soil is under the leaves
of a large lily during the summer and in the winter is barren.
In
central Virginia I found needle ice that had pushed up a thin crust of soil
by about 3 cm, below.
In my
observations on ice, I found ice growing on pebbles and explored this process
by conducting experiments in a freezer of a refrigerator. Most of the time I
used sand as my base material but on occasion I used a fairly
heavy soil with relatively large clay content as the base material.
The results below show what I got one time in this setup.
Needle
ice can vary in appearance but always shows the consistent growth of ice
perpendicular to the land surface. In
many cases the freezing plane is a little below the surface and thus some
soil and particles on the surface will be lifted by the needle ice.
Needle
ice is likely to occur throughout the world where there is freezing and
thawing, and the soil contains sufficient proportions of fine particles to
wick water toward the surface through capillarity. Bibliography Lawler,
D. M., 1988. A Bibliography of Needle
Ice. Cold Regions Science and Technology, 15, pp.
295-310. Meentmeyer, V. and J. Zippen, 1981. Soil
Moisture and Texture Controls of Selected Parameters of Needle Ice
Growth. Earth Surfaces Processes and Landforms. Vol.
6, pp. 113-125. Outcalt, S. I., 1971. An Algorithm for Needle Ice Growth. Water
Resources Research, Vol. 7 pp. 394-400. There
is a Wikipedia page on needle ice: http://en.wikipedia.org/wiki/Needle_ice
Related web pages
showing products of Ice
Segregation Hair Ice - ice growing on pieces
of dead tree branches on the ground or suspended in the tree Ice Flowers - ice growing on
the stems of a few species of plants Pebble Ice - ice growing on
small rocks through ice segregation Sub-surface
ice formation in geologic environments Closing Comments On
a web site
discussing frost heave a photo shows the presence of ice needles about a
meter below the surface. Note that the ground had to
be removed to expose these needles. The
presence of needle ice at the surface, a centimeter below the surface,
and a meter below the surface are manifestations of the same processes.
The Wikipedia page on
Ice Segregation discusses even deeper occurrences of such ice. Some
of the ice formed by Ice Segregation can be quite attractive but in general
needle ice does not take such forms. But it is quite common where
freezing occurs and can be an important in shaping the land surface
and contributing to surface erosion. Thank
goodness for the Internet and digital cameras for they let us exchange
information about these small ice formations. Please look for
interesting ice when the freeze/thaw processes are underway. With
your help we might gain more insights about these products of ice
segregation. For
more on my perspectives see my web pages at http://www.jrcarter.net/ice/ Feel
free to contact me at jrcarter@ilstu.edu to
share your photos of ice of this nature from your early morning
outings. |