Frazil Ice


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frazil ice

[′fra·zəl ‚īs]
(hydrology)
A spongy or slushy accumulation of frazil in a body of water. Also known as needle ice.

Frazil Ice

 

an accumulation of loose, spongy ice within a body of water (deep frazil ice) or on its surface (surface frazil ice). Frazil ice forms from tiny crystals of deep ice (intermediate and bottom ice) and from grease ice and slush. It occurs before the freeze-up when water is supercooled below 0°C, primarily on mountain rivers and rivers with rapids, below polynyas and the lower pools of hydroengineering complexes, and, occasionally, on lowland rivers and lakes.

Frazil ice, carried downstream by the current, covers large areas and dams up the channel, causing ice jams. It also considerably impedes the operation of hydroengineering structures by clogging up the filters of water intakes and the aperture grills at hydroelectrical power plants.

References in periodicals archive ?
In years without fall storms, such as 1971 and 1985, Reimnitz and Kempema (1987) did not notice the production of large amounts of slush or frazil ice, but during the fall storm of 1978, the slush-ice berm was 4 m thick.
Flume studies and field observations of the interaction of frazil ice and anchor ice with sediment.
Some supercooled water may nucleate on particles in the water column or grow on small ice crystals scoured from surface sea ice, forming frazil ice. Alternatively, ice may nucleate on, or frazil ice may attach to, benthic structures (i.e., rocks, mud, detritus, or organisms), thereby forming anchor ice.
If the water is flowing during this nucleation, the resulting frazil ice may adhere to epibenthic organisms, collecting on exposed surfaces or drifting alongside and underneath.
The emergency occurred when slush, known as frazil ice, plugged up the Millers River and diverted the water flow down Pequoig Avenue, through backyards and into Cass Meadow.
Opaque top Snow layer (1), cm cm g/[cm.sup.3] 1/97 11 0 -- 2/97 1 0 -- 3/97 4 0 -- 4/97 2 0 -- 5/97 14 4 x 6/97 13 0 -- 1/98 10 5 0.33 2/98 8 5 0.22 3/98 7 5 0.26 4/98 7 5 0.34 5/98 11 5 0.32 6/98 14 5 0.34 1/99 23 18 0.25 2/99 3 24 (0.5) (2) 3/99 3 31 (0.5) (2) 4/99 23 5 0.55 5/99 31 5 0.32 6/99 36 5 0.37 (1) snow-ice in the lakes, snow-ice or frazil ice in the river; (2) wet snow and lower 12 cm slush, 0.5 g/[cm.sup.3] is a rough average density Table 3.
Evolution of frazil ice in natural bodies of water.
The interface between the near-fresh upper water and underlying seawater is a potential site of frazil ice production, owing to the different freezing temperatures of the two water masses.
"Frazil ice" consists of fine ice crystals that form in suspension in supercooled, turbulent water.