In terms of height, remoteness and the severe and changeable weather, the Cairngorms are the most arduous area in the United Kingdom. The plateau area has a Tundra climate (Köppen "ET"), and the shattered terrain is more like the high ground in high-arctic Canada or northern Norway than anywhere in the Alps or Rockies. The weather often deteriorates rapidly with altitude so that, when there are moderate conditions 150 m below the plateau, the top can be stormy or misty, and there can be icy or powdery snow. Even when no snow is falling, the wind can whip up lying snow to produce white-out conditions for a few metres above the surface, and snowdrifts can build up rapidly in sheltered places. Gravel can be blown through the air, and walking can be impossible.