Needle ice is a needle-shaped column of ice formed by groundwater. Needle ice forms when the

temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied o ...

of the

soil Soil, also commonly referred to as earth or dirt, is a mixture of organic matter, minerals, gases, liquids, and organisms that together support life. Some scientific definitions distinguish ''dirt'' from ''soil'' by restricting the former ...

is above and the surface temperature of the air is below . Liquid water underground rises to the surface by

capillary action Capillary action (sometimes called capillarity, capillary motion, capillary rise, capillary effect, or wicking) is the process of a liquid flowing in a narrow space without the assistance of, or even in opposition to, any external forces li ...

, and then freezes and contributes to a growing needle-like ice column. Needle ice requires a flowing form of water underneath the surface, from that point it comes into contact with air that is below freezing. This area of the process usually occurs at night when temperature reaches its low point. From then on, it produces the needle like structure known as "Needle Ice". The ice needles are typically a few centimetres long. While growing, they may lift or push away small soil particles. On sloped surfaces, needle ice may be a factor contributing to

soil creep Downhill creep, also known as soil creep or commonly just creep, is a type of creep characterized by the slow, downward progression of rock and soil down a low grade slope; it can also refer to slow deformation of such materials as a result of ...

.Isbell, D.:
Needle Ice on Mt. Osceola
'', EPOD of July 10, 2005. URL last accessed 2007-12-07.Pidwirny, M.

URL last accessed 2007-12-07. Alternate names for needle ice are "

frost Frost is a thin layer of ice on a solid surface, which forms from water vapor in an above-freezing atmosphere coming in contact with a solid surface whose temperature is below freezing, and resulting in a phase change from water vapor (a g ...

pillars" ("Säuleneis" in

German German(s) may refer to: * Germany (of or related to) **Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also German nationality law **Ge ...

), "

column", "Spew Ice", "Kammeis" (a German term meaning "comb ice"), "Stängeleis" (another German term referring to the stem-like structures), "shimobashira" (霜柱, a Japanese term meaning frost pillars), or "pipkrake" (from Swedish ''pipa'' (tube) and ''krake'' (weak, fine), coined in 1907 by Henrik Hesselman).Lawler, D. M.: "Some observations on needle ice", ''Weather'', vol. 44, pp. 406–409; 1989. The similar phenomena of frost flowers and hair ice can occur on living or dead plants, especially on wood.

Formation

In order for needle ice to form there needs to be a process of

ice segregation Ice segregation is the geological phenomenon produced by the formation of ice lenses, which induce erosion when moisture, diffused within soil or rock, accumulates in a localized zone. The ice initially accumulates within small collocated pores ...

, which only occurs in a

porous medium A porous medium or a porous material is a material containing pores (voids). The skeletal portion of the material is often called the "matrix" or "frame". The pores are typically filled with a fluid ( liquid or gas). The skeletal material is u ...

when supercooled water freezes into existing ice, growing away from the ice/water interface. As water permeates the ice, it becomes segregated into separate pieces of ice in the form of lenses, ribbons, needles, layers or strands of ice. Needle ice is commonly found along stream banks or soil terraces. It is also found by gaps around stones and others areas of patterned ground. The variety of soil properties also affects where it is found. Places where the soil is much deeper and richer can affect the growth of the ice. Consequently, the deeper the soil, the larger the water content allows it to develop. It can be evidently formed anywhere where underground water is exposed to open (freezing) air. Needle ice is most suitable in soils with a high

silt Silt is granular material of a size between sand and clay and composed mostly of broken grains of quartz. Silt may occur as a soil (often mixed with sand or clay) or as sediment mixed in suspension with water. Silt usually has a floury feel ...

and organic matter content. Needle ice consists of groups of narrow ice slivers that are up to several centimeters long. Although the literature states that the largest recorded needle ice was at 10 cm in length, specimens 15-20 cm in length have been observed at Gerðuberg, for example. Needle Ice Flume Gorge 1

Needle ice grows up slowly from the moist and water-penetrable soil, and melts gradually in the sun. It can vary in appearance but always shows the consistent growth of ice perpendicular to the surface of the ground. Needle ice looks like a series of filamentous crystals, and is straight or curved in shape. It usually forms in the morning when the temperature drops below freezing point (0 °C).

Environmental impacts

The emergence of needle ice has been recognized as a geomorphic agent of soil disturbance, causing a number of small-scale landforms. Needle ice phenomena play a particularly significant role in patterned ground in periglacial environments. The growth of needle ice lifts a detached, frozen soil crust riding on top of the layer of ice. When the crust and the ice melt, the soil surface settles back irregularly. This phenomenon is linked to erosion, particularly on streambanks. Needle ice tends to move rocks in the soil up toward the surface and to shift rocks on the surface into nearby depressions. Depressions caused by needle ice activity are known as needle-ice pans, and lumps caused by needle ice are known as "nubbins".

Plant growth

Needle ice affects the growth of plants.

Seedling A seedling is a young sporophyte developing out of a plant embryo from a seed. Seedling development starts with germination of the seed. A typical young seedling consists of three main parts: the radicle (embryonic root), the hypocotyl (emb ...

s are often heaved to this surface by needle ice. When the ground hardens the stems and roots of the seedling, they are gripped by the soil and then the formation of needle ice is what pushes them up and out the ground. When the needle ice melts, the seedlings do not settle correctly back into the ground causing them to die. Even if the seedlings are partially heaved by the needle ice, they can still die due to root

desiccation Desiccation () is the state of extreme dryness, or the process of extreme drying. A desiccant is a hygroscopic (attracts and holds water) substance that induces or sustains such a state in its local vicinity in a moderately sealed container. ...

References

External links

Needle ice video

Another needle ice video
{{ice Snow or ice weather phenomena Water ice Soil science

Formation

Environmental impacts

Plant growth

See also

References

Further reading

External links