Drift snow

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Fresh snowdrift accumulation, clearly recognizable by the wavy snow surface (wind direction from the left)

As driven snow is called snow , which the wind has blown and has been deposited in a sheltered spot. This can be the case , for example, on downwind slopes: the wind blows the snow over the ridge , which falls to the ground in the lee of the ridge and forms a blanket of snowdrift there.

Since large amounts of snow are collected in this way by the wind, thick snow-drifting layers can arise in a short time, which are also only very loosely connected to the old layers of snow. Within the snowdrift accumulation itself, however , the snow crystals show a high degree of binding: In contrast to freshly fallen powder snow , the flakes of which come to lie on top of each other, the crystals are deformed and interlocked after the wind transports them and thus form dangerous snow boards . Drift snow is therefore one of the most common causes of avalanches . It can also be related to the nigg effect .

For winter sports enthusiasts , especially those who go on ski tours, recognizing drift snow is very important for this reason. A sign of snow drift can be a dune- like undulating snow surface. Such is a typical deposit phenomenon. The steep side of the dunes shows the leeward side , so that the wind direction can also be read. Also cornices , Sastrugi and blown off by the wind combs can the experienced skiers reveal the location of snowdrift accumulations. Drift snow is a particular danger if it is covered by subsequent snowfalls and is therefore difficult to see.

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