Frazil Ice

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frazil ice

[′fra·zəl ‚īs]
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 ?
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.
At times, Ship Creek would fill with frazil ice causing intake screens at the treatment plant to clog, requiring operating personnel to shovel frazil ice away from the intake.
In turbulent water, free frazil ice crystals (size 1 mm or less) appear first, and when the buoyancy of these crystals together overcomes the turbulence, they surface and form a solid ice sheet.