is extremely dangerous to low-flying aircraft, particularly those attempt- 

 ing to land. Pilots have well described the condition as "like flying in a 

 bowl of milk." An analogous condition in the antarctic regions is called 

 an antarctic whiteout. 



AVALANCHE: ( 1 1. B.)— Masses of snow detached from great heights in 

 the mountains and acquiring enormous bulk by fresh accumulations as 

 they descend. When they fall into the valleys below, they often cause 

 great destruction. Cf. glacier. 



AVALANCHE ICE: (II.A.3.e.) — An ice mass fed entirely by avalanches 

 from the 6dge of continental ice, island ice, highland ice, or 

 cirque ice; or from the overhanging end of a valley glacier or wall- 

 sided glacier cut off high on a mountain side. See land ice. Cf. 

 avalanche. 



BALL ICE: (I.A.l.f.) — Numerous floating spheres of sea ice having 

 diameters of one to two inches. The balls are very soft and spongy; 

 no internal structure can be distinguished clearly. The balls are generally 

 in belts similar to slush which forms at the same time. Ball ice has 

 very rarely been reported. 



BARBER: (V.B.)— Frost smoke. 



BARRANCA: (II.B.) — A rift in piedmont ice, shelf ice, or ice tongue 

 afloat. 



BARRIER: 



(1) ( II. A.4.a.)— Shelf ice. 



(2) (II. A. 4. a.) — Shelf ice in some particular geographic locality, e.g., 

 Ross Barrier. 



BARRIER ICEBERG: (II.A.5.a.)— Tabular iceberg. See iceberg. 

 BAY: (I.C.l.d.) — An inward bend of the ice edge or the ice limit, 



formed either by wind or current. See water opening. 

 BAY ICE: (I.A.3.C.) — Young, flat ice of sufficient thickness to impede 



navigation. In the antarctic this term also has been used at times for 



heavy land floes. 

 BELT: (I.A.l.f.) — A relatively narrow band of fragments of floating 



or fast ice of any concentration. Cf. patch, tongue. (Fig. 9.) 

 BENDING: (V.C.) — The first stage in the formation of pressure ice 



caused by the action of current, wind, fide, or air temperature changes. 



Bending is more characteristic of thin, plastic ice than heavier forms. 



(Fig. 79.) 

 BERG: ( II. A.5.a.)— Iceberg. 

 BERGSCHRUND : (II.B.) — The crevasse or series of crevasses, deep 



and often broad, frequently occurring at the source of a valley glacier 



between the glacier ice and the mountain itself. The bergschrund 



becomes filled with snow and closes up during the winter, but reopens 



on the return of summer. 



