end and the ice tongue is bordered all around its seaward face by 

 sharply defined perpendicular cliffs between 10 and 200 feet in height. 

 The seaward end of a well-developed tongue rises and falls freely with 

 the tide, and a tide crack between it and the sea ice is therefore usually 

 ill-defined or absent altogether. (Fig. 76.) 



ICE WORN: (V.C.) — Abraded by ice; specifically, rubbed, scratched, or 

 channeled by glacial action. 



ICICLE: (V.C.)- — A pendent, usually conical, mass of ice formed by the 

 freezing of dripping water (Figs. 109, 110) . 



ICING (of ships): (V.A.) — The formation and accumulation of ice on 

 ships. Icing is caused principally by the freezing of spray on the super- 

 structure when the sea water is about 30°F., the air temperature 20°F. or 

 below, and the wind force 4 or greater. It will also form during oc- 

 casional ice storms. 



During icing in the arctic the wind, often rapidly veering, is usually 

 northerly, stormy, squally, and sometimes described as piercing. The 

 superstructure of the ship becomes very cold, so that any spray blown 

 over it freezes immediately. The ice first envelops the lower weather 

 decks and rails and with increasing wind climbs higher on the super- 

 structure. Ice may build up at rates as high as l 1 /^ inches per hour, 

 particularly with a headwind. If the wind is on the beam, the ice will 

 form on that side of the ship and thus cause a list which may become 

 serious. Maximum icing takes place in bad weather, so that the difficul- 

 ties for the crew engaged in de-icing are greatly increased by the ship's 

 motion as well as the extreme cold. In general, smaller, well loaded 

 vessels ice up more quickly than larger vessels of shallower draft. The 

 ice is grayish white. Because of the salt content it is not as slippery 

 or brittle as the ice formed in ice storms. 



Icing resulting from ice storms at sea occurs when the raindrops are 

 near freezing or supercooled and the ship's superstructure is below the 

 freezing temperature of rain. The ice first forms on the masts, arms, 

 lines, and antennas, and gradually overspreads the entire vessel. The 

 ice thus formed is transparent, of uniform thickness, and very slippery. 

 While it is probably more adhesive than frozen spray, it is more brittle. 

 The total accumulation usually is not sufficient to endanger the stability 

 of the ship, but because of the greater distance of the weight from the 

 center of gravity the torque is greatly increased. Damage usually occurs 

 to antennas, particularly the rigid type. A small, but very real danger to 

 personnel exists when ice fragments from masts and lines fall to the 

 decks. 



Icing may also occur on lakes. Cf. ice storms, de-icing. (Figs. 104, 

 105.) 



IRREGULAR ICEBERG: (I I. A. 5. a.)— Pinnacled iceberg, 



9559340—52—5. 



17 



