US Army Corps of Engineers
Ice Jam Database
IAHR Multilingual Ice Terminology - Basic English Terms

International Association for Hydraulic Research Association Internationale de Recherches Hydrauliques Section on Ice Problems/Seion De Glaces



Published by the Research Centre for Water Resources Budapest, 1980


  1. Agglomerate

    An ice cover of floe formed by the freezing together of various forms of ice.
  2. Anchor Ice

    Submerged ice attached or anchored to the bottom, irrespective of the nature of its formation.
  3. Anchor Ice Dam

    An accumulation of anchor ice which acts as a dam and raises the water level.
  4. Beginning of the breakup (Date) Rivers

    Date of definitive breaking or movement of ice due to melting, current, or rise of water level.
  5. Beginning of the breakup (Date) Lakes

    Date of visual evidence of initial deterioration along shoreline - appearance of shore leads.
  6. Beginning of Freeze-up (Date)

    Date on which ice forming stable winter ice cover first observed on the water surface.
  7. Black Ice

    Transparent ice formed in rivers and lakes.
  8. Border Ice

    An ice sheet in the form of a long border attached to the shore.
  9. Brackish Ice

    Ice formed from brackish water.
  10. Brash Ice

    Accumulation of floating ice made up of fragments not more than 2 metres across; the wreckage of other forms of ice.
  11. Break-up

    Disintegration of ice cover.
  12. Break-up Date

    The date on which a body of water is first observed to be entirely clear of ice, and remains clear thereafter.
  13. Break-up Period

    Period of disintegration of an ice cover.
  14. Candle Ice

    Rotten columnar-grained ice.
  15. Channel lead

    Elongated opening in the ice cover caused by a water current.
  16. Columnar Ice

    Ice consisting of columnar shaped grain. The ordinary black ice is usually columnar-grained.
  17. Concentration

    The ratio in eights or tenths of the water surface actually covered by ice to the total area of surface, both ice covered and ice free, at a specific location or over a defined area.
  18. Concentration Boundary

    A line approximating the transition between two areas of floating ice with distinctly different concentrations.
  19. Consolidated Ice Cover

    Ice cover formed by the packing and freezing together of floes, brash ice and other forms of floating ice.
  20. Corn Snow Ice

    Rotten granular ice.
  21. Crack

    A separation formed in an ice cover of floe that does not divide it into tow or more pieces.
  22. Deformed Ice

    A general term for ice which has been squeezed together and forced upwards in places /and downwards/. Subdivision are rated ice, ridged ice, hummocked ice, and other similar deformations.
  23. Dendrites

    Thin branch-like growth of ice on the water surface.
  24. Diffuse Ice

    Poorly defined ice edge limiting an area of dispersed ice; usually on the leeward side of an area of floating ice.
  25. Drifting Ice

    Pieces of floating ice moving under the action of wind and/or currents.
  26. Dry Crack

    Crack visible at the surface but not going right through the ice cover, and therefore dry.
  27. Duration of Ice Cover

    The time from freeze-up to break-up of an ice cover.
  28. Dynamic Ice

    Pressure due to a moving ice cover or drifting ice. Pressure occurring at movement of first contact termed Ice Impact Pressure.
  29. Floating Ice

    Any form of ice floating in water.
  30. Floc

    A cluster of frazil particles.
  31. Flooded Ice

    Ice which has been flooded by melt water or river water and is heavily loaded by water and wet snow.
  32. Fracture

    Any break or rupture formed in an ice cover or floe due to deformation.
  33. Fracture Zone

    An area which has a great number of fractures.
  34. Fracturing

    Deformation process whereby ice is permanently deformed, and fracture occurs.
  35. Frazil

    Fine spicules, plates or discoids of ice suspended in water. In rivers and lakes it is formed in supercooled turbulent waters.
  36. Frazil Slush

    An agglomerate of loosely packed frazil which floats or accumulates under the ice cover.
  37. Freeze-up Date

    The date on which the water body was first observed to be completely frozen over.
  38. Freeze-up Period

    Period of initial formation of an ice cover.
  39. Frost Smoke

    Fog-like clouds due to contact of cold air with relatively warm water, which can appear over openings in the ice or leeward of the ice edge and may persist while ice is forming.
  40. Frozen Frazil Slush

    Accumulation of slush that has completely frozen.
  41. Granular Ice

    Ice made of granular ice grains.
  42. Grounded Ice

    Ice which has run aground.
  43. Glare Ice

    Ice cover with a highly reflective surface.
  44. Hanging /ice/ Dam

    A mass of ice composed mainly of slush or broken ice deposited under an ice cover in a region of low flow velocity.
  45. Hinge Crack

    Crack caused by significant changes in water level.
  46. Hummocked Ice

    Ice piled haphazardly one piece over another to form an uneven surface.
  47. Hummock

    A hillock of broken ice which has been forced upward by pressure.
  48. Hummocking

    The pressure process by which ice is forced into hummocks.
  49. Ice Boom

    Floating structure designed to retain ice.
  50. Ice Bridge

    A continuous ice cover of limited size extending from shore to shore like a bridge.
  51. Ice Clearing

    Break-up prior to full melting.
  52. Ice Cover

    A significant expanse of ice of any possible form on the surface of a body of water.
  53. Ice Crossing

    Man-made ice bridge.
  54. Ice Edge

    The demarcation at any given time between the open water and ice of any kind, whether static or dynamic. It may be termed compacted or diffuse.
  55. Ice Floe

    Free floating piece of ice greater than one metre in extent.
  56. Ice Foot

    A narrow fringe of thickened ice attached to the shore unmoved by changes in water level.
  57. Ice-Free

    No floating ice is present.
  58. Ice Gorge

    The gorge or opening left in a jam after it has broken.
  59. Ice Impact Pressure

    /see Dynamic Ice/
  60. Ice Jam

    An accumulation of ice at a given location which, in a river, restricts the flow of water.
  61. Ice Jamming

    The process of accumulation of ice to form an ice jam.
  62. Ice Ledge

    Narrow fringe of ice that remains along the shores of river after break-up.
  63. Ice Needle

    A small needle-like ice crystal formed under certain nucleation conditions.
  64. Ice Pot Hole

    A roundish hole formed in the ice by water motion in a narrow crack or small hole or by the effect of radiation. It may or may not extend through the ice cover.
  65. Ice Push

    Compression of an ice cover particularly at the front of a moving section of ice cover.
  66. Ice Rind

    See ice term, similar to skim ice.
  67. Ice Run

    Flow of ice in a river. An ice run may be light or heavy, and may consist of frazil, anchor, slush, or sheet ice.
  68. Ice Sheet

    A smooth continuous ice cover.
  69. Ice Shove

    On-shore ice push caused by wind, and currents, changes in temperature, etcetera.
  70. Ice Twitch

    Downstream movement of a small section of an ice cover. Ice twitches occur suddenly and often appear successively.
  71. Ice Wrinkle

    An uneveness appearing in the surface of an ice cover due to folding by horizontal pressure.
  72. Insitu Break-up

    Melting in place.
  73. Lake Ice

    Ice formed on a lake, regardless of observed location.
  74. Lead

    Long, narrow opening in the ice.
  75. New Ice

    A general term for recently formed ice which includes frazil ice, slush, shugs/sludge/, and other types of ice.
  76. Pancake Ice

    Circular flat pieces of ice with a raised rim; the shape and rim are due to repeated collisions.
  77. Polynya

    Any non-linear shaped opening enclosed by ice. Polynyas may contain brash ice and/or be covered with new ice.
  78. Puddle

    An accumulation of melt water on ice, mainly due to melting snow but in the more advanced stages also to the melting of ice. Initial stage consists of patches of melted snow.
  79. Rafted Ice

    Type of deformed ice formed by one piece of ice overriding another.
  80. Rafting

    Pressure processes whereby one piece of ice overrides another. Most common in new ice.
  81. Ridge

    A line or wall of broken ice forced up by pressure. May be fresh or weathered.
  82. Ridged Ice

    Ice piled haphazardly one piece over another in the form of ridges or walls.
  83. Ridging

    The pressure process by which ice is forced into ridges.
  84. River Ice

    Ice formed on a river, regardless of observed location.
  85. Rotten Ice

    Ice in an advanced stage of disintegration.
  86. Rough Ice

    General term for ice covers with rough surfaces.
  87. Sea Ice

    Any form of ice originating from the freezing of sea water.
  88. Shale Ice

    An accumulation of thin broken plates of ice formed when skim ice breaks up.
  89. Shear Crack

    Crack formed by movement parallel to the surface of the crack.
  90. Shearing

    Motion of an ice cover due to horizontal shear stresses.
  91. Shore Lead

    A water opening along the shore.
  92. Shore Depression

    Depression in the ice cover along the shore often caused by change in water level.
  93. Sludge

    An accumulation of spongy ice lumps formed from compressed frazil slush, snow slush, or anchor ice.
  94. Skim Ice

    Initial thin layer of ice on a water surface.
  95. Slush Ball

    The result of extremely compact accretion of snow, frazil, and ice particles. This is produced by either wind and wave action along the shore of lakes or in long stretches of turbulent flow in rivers.
  96. Slush Ice Run

    Ice run composed mainly of slush ice.
  97. Snow Ice

    Ice that forms when snow slush n an ice cover freezes. It has a white appearance due to presence of air bubbles.
  98. Snow Slush

    Snow which is saturated with water on ice surfaces, or as a viscous mass floating in water after a heavy snowfall.
  99. Stranded Ice

    Ice that has been floating and has been deposited on the shore by a lowering of the water level.
  100. Static Ice Pressure

    Pressure developed by a static ice cover.
  101. Surface Crack

    Crack visible at the surface.
  102. Tabular Ice

    A particular type of ice whose grains have large horizontal dimensions.
  103. Thaw Holes

    Vertical holes in ice formed when surface puddles melt through to the underlying water.
  104. Thermal Crack

    Crack caused by contraction of ice due to change in temperature.
  105. Through Crack

    Crack extending through the ice cover.
  106. Tide Crack

    Crack caused by the rise and fall of tides.
  107. Unconsolidated (Ice Cover)

    Loose mass of floating ice.
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