rouleau de neige

OBS: Les rouleaux de neige se forment lorsque la neige, étant assez humide pour être cohésive, peut être charriée par le vent et rouler le long des pentes. Ils peuvent avoir plusieurs centimètres de longueur et de diamètre.

CONT: A snow roller is a rare meteorological phenomenon in which large snowballs are formed naturally as chunks of snow are blown along the ground by wind, picking up material along the way, in much the same way that the large snowballs used in snowmen are made. Unlike snowballs made by people, snow rollers are typically cylindrical in shape, and are often hollow since the inner layers, which are the first layers to form, are weak and thin compared to the outer layers and can easily be blown away, leaving what looks like a doughnut or jelly roll. Snow rollers have been seen to grow as large as two feet in diameter. ... snow rollers are more common in hilly areas. However, [they are] a very rare phenomenon.
OBS: It is shaped like a rolled sleeping bag, some reaching four feet across and seven feet in diameter.