Nigg effect

The Nigg effect (after its discoverer, the Swiss mountain guide Paul Nigg) occurs when surface hoar frost forms and represents a hazard pattern for avalanches . Due to its poor visibility, small areas and its occurrence in good weather conditions, it is considered insidious and a classic expert trap . It is particularly common in early winter (around December) and late winter (around April and May).

The trigger of the effect is warm, humid air, e.g. B. rises through solar radiation on a southern slope to a mountain ridge or mountain ridge . If it meets the other, usually cooler and shady side, surface hoop forms in the immediate vicinity of the ridge, the strip-like extension of which has a width of a few meters. Unless reached this area of snow, such as driven snow , the frost forms a sliding layer for avalanches and is also no longer be seen as a danger zone.

literature

• Eike Roth: Avalanches. Understand - Avoid - Practical Tips . Bergverlag Rother, 2013, ISBN 978-3-7633-6085-7 , p. 32 f . ( limited preview in Google Book search).

Web links

• Avalanche risk pattern on the website of the Tyrolean Avalanche Warning Service