Ice Spike

Lore & Background

Natural ice spikes can grow into shapes other than a classic spike shape, and have been variously reported as ice candles, ice towers or ice vases as there is no standard nomenclature for these other forms. One particularly unusual form takes the shape of an inverted pyramid. Although natural ice spikes are usually measured in centimeters or inches, a report that appeared in the Harbor Creek Historical Society Newsletter by Canadian Gene Heuser, who hiked across frozen Lake Erie in 1963, spoke of 'small pinholes in the ice through which the water below was periodically forced under pressure to spout up into the air and freeze' producing five-foot-high (1.5 m) 'frozen spurts that looked to him like telephone poles standing straight up all over the lake'.

In Their Own Story

Ice spikes have been reported as a rare natural phenomenon for decades. A model of the mechanism of formation was put forth independently by O. Bally and H.E. Dorsey in the early 20th century and this is still the most widely accepted explanation of the phenomenon today. Spikes tend to form in containers such as bird baths and pet drinking bowls, where the water freezes quickly, rather than in large bodies of water such as lakes and ponds. A number of web pages displaying photographs of unusual ice formations and discussing the phenomenon have been published, and a number of cases of ice spikes being formed on ice cubes in domestic refrigerators have been reported. The ability to grow ice spikes in a controlled environment has prompted a small number of investigations by the researchers in the Physics Department of the California Institute of Technology under the direction of Kenneth G. Libbrecht into the conditions needed for the spikes to form.

Reader's Guide

Water expands by 9% as it freezes. Occasionally the surface can freeze over except for a small hole; the continuing freezing and expansion of water that is below the surface ice then slowly pushes the remaining water up through the hole. Reaching very cold air, the edge of the extruded water freezes while remaining liquid in the center. More freezing below pushes more water up, the edge freezes, and so on. If the rate of extrusion of water is the same as the rate of freezing at the lip of the hole, then this process is continually repeated and successive layers form an upward-growing tube of ice. As with snowflakes, the shape of the tube is controlled by the molecular nature of water. The simplest shape of an ice crystal that reflects its internal structure is a hexagonal prism. The top and bottom faces of the crystal are hexagonal planes called basal planes and the direction that is perpendicular to the basal planes is called the c-axis. Small ice spikes can be formed artificially on ice cubes produced in domestic refrigerators; using distilled water in plastic ice cube trays. The formation of the spike is similar to that of the naturally occurring spike in that the expansion of interior water and, the reduction of volume in the interior of the cube, increase the pressure on the water pushing it upward through the hole. The growth of the tube ceases when the drop at the top of the tube freezes entirely, which is substantially before the rest of the water in the cube is frozen. This method produces small spikes which are usually round or triangular in cross section with sharp tips. Experiments using this method have been carried out in laboratory settings but it has been found that spikes are less likely to form in ice cubes made from non-distilled water as impurities in the water inhibit spike formation. This poses the question of how naturally occurring ice spikes form in tapwater, rainwater, or other such sources of water, despite the impurities present inside the water, which should impede ice growth. Research by Libbrecht and Lui has suggested that, in the case of the small spikes grown in a refrigerator, impurities become increasingly concentrated in the small unfrozen droplet at the top of the tube reducing the freezing rate and slowing the growth of the tube. However, they believe that on the rare occasions when exceptionally large spikes grow in natural, outdoor ice formations, some other mechanism must remove the impurities that build up at the top of the growing tube. Either impurities are forced into pockets that freeze more slowly, or perhaps a convective flow, which would be insignificant in the smaller, artificially grown spikes, replaces the water at the top of the tube with fresh water from below.

Did You Know?

• Ice spikes are often in the shape of an inverted icicle, projecting upwards from frozen water.
• The Bally–Dorsey model for ice spike formation was proposed in the early 20th century but not tested in the lab for many years.
• Natural ice spikes have been reported as ice candles, ice towers, or ice vases, with no standard nomenclature.
• Gene Heuser reported five-foot-high ice spikes on frozen Lake Erie in 1963, looking like telephone poles.
• Ice spikes can be artificially produced by freezing distilled water in plastic ice cube trays in domestic refrigerators.