ICE PILLAR 



ice flowers — 1. Formations of ice crystals on the 

 surface of a quiet, slowly freezing body of water. 



2. (also called /ms(' /^oii'ers). Delicate tufts 

 of hoarfrost that occasionally form in great 

 abundance on an ice or snow surface (surface 

 hoar) ; it also forms as a type of crevasse hoar 

 or window frost. 



3. See Tyndall flowers, 



ice fog — A type of fog, composed of suspended 

 particles of ice, partly ice crystals 20 to 100 

 microns in diameter but chiefly, especially when 

 dense, droxtals (crystals) 12 to 20 microns in 

 diameter. It occurs at very low temperatures, 

 and usually in clear, calm weather in high lati- 

 tudes. The sun is usually visible and may cause 

 halo phenomena. 



Ice fog is rare at temperatures warmer than 

 — 30°C or — 20°F, and increases in frequency 

 with decreasing temperature until it is almost 

 always present at air temperatures of — 45°C 

 or — 50°F in the vicinity of a source of water 

 vapor. Such sources are the open water of 

 fast-flowing streams or of the sea, herds of 

 animals, volcanoes, and especially products of 

 combustion from heating or propulsion. At 

 temperatures warmer than — 20°F, these sources 

 can cause steam fog of liquid water droplets, 

 which may turn into ice fog when cooled. See 

 frost smoke. (5) 



ice foot — (also called heUicatter, haUycadder, 

 catter. cadcler, collar ice, fast ice belt). Sea ice 

 firmly frozen to the shore at the high tide line, 

 and unaffected by tide. There are several 

 varieties of ice foot. (74) 



Ice foot is formed by the freezing of sea water 

 during ebb tide, and of spray. It is separated 

 from the floating sea ice by a tide crack; in 

 many areas it offers a fairly level, continuous 

 route for surface travel. (5) 



ice free — Water surface completely free of ice. 

 (74) 



ice fringe — A belt of sea ice extending a short 

 distance from the shore. (68) 



ice front — (also called front, ice cliff, ice face, ice 

 loall). 1. The seaward facing, cliff-like edge 

 of an ice shelf (so called by the British Ant- 

 arctic Place-names Committee). 



2. Any vertical wall of ice. 

 (5) 



ice gang — See debacle. 



ice gruel — A type of slush formed by the irregular 

 freezing together of ice crystals. (68) 



ice hummock — See hum:nock. 



ice island — 1. A large tabular fragment of shelf 

 ice found in the Arctic Ocean. Nearly one hun- 

 dred have been identified since the first one was 

 discovei-ed on aircra.ft radar in 1946. All have 

 level, slightly undulating surfaces 10 to 25 feet 

 above water, and most appear to have calved 

 from the Ward Hunt ice shelf off the northern 

 coast of Ellesmere Island. Ice islands are 

 smaller than the largest tabular icebergs of the 



antarctic, the largest one kno^vn being about 300 

 square miles in area. They are up to 175 feet 

 thick and unlike the surrounding pack ice, they 

 are influenced more by currents than by wind. 

 Several ice islands have been occupied as drift 

 stations. 



2. Any tabular iceberg. (59) Rare. 



3. A giant floe. (59) Rare. 



4. An island completely covered by ice and 

 snow. (59) Rare. 



ice island iceberg — (also called dome-shafed ice- 

 berg). An iceberg having a conical or dome- 

 shaped summit. Such icebergs are often mis- 

 taken by mariners for ice-covered islands. Also 

 called ice island. (68) Obsolete term. 



ice jam — Fields of lake or sea ice thawed loose 

 from the shores in early spring, and blown 

 against the shore, sometimes exerting great 

 pressures. (5) 



ice keel — From the point of view of the sub- 

 mariner, a downward projecting ridge on the 

 underside of the ice canopy; the submerged 

 counterpart of a pressure ridge. Ice keels may 

 extend as much as 50 meters (164 feet) below 

 sea level. (7) 



Icelandic low — The low pressure center located 

 near Iceland (mainly between Iceland and south- 

 ern Greenland) on mean charts of sea-level 

 pressure. It is a jirincipal center of action in 

 the atmospheric circulation of the Northern 

 Hemisphere. (5) 



ice ledge — See ice foot. 



ice limit — The average position of the ice edge in 

 any given month or period, based on observa- 

 tions over a number of years. (74) 



ice mosaic — See ice breccia. 



ice pack — 1. See pack ice. 



2. See arctic pack. 



3. See ice cluster. 



ice pan — ( also called ?ipan). A large flat piece of 

 sea ice protruding from a few inches to 3 feet 

 above the water, usually composed of winter ice. 

 (59) Rare. 



ice pedestal — (or mushroom ice, ice pillar). A 

 pillar of ice with a roimd, expanded top formed 

 when a portion of an ice-covered area is pro- 

 tected from the melting effect of sunlight by 

 some surface object. (59) 



ice period — The time between first appearance and 

 final clearance of ice during any year. 



ice piedmont — Ice covering a coast strip of low- 

 Ij'ing land backed by mountains. The surface 

 of an ice piedmont slopes gently seaward, may 

 range from a width of about 50 meters (164 

 feet) to 50 kilometers (27 n. miles) and fringes 

 long stretches of coastline with ice cliffs. Ice 

 piedmonts frequently merge into ice shelves. 

 (7) 



ice pillar — 1. See ice pedestal. 



2. Any ice formation of columnar shape. 

 (59) 



83 



