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Snow Physics

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Head: Dr. Henning Löwe 

The core topic of the team "Snow Physics" is structure and property of snow and firn at different scales. Our most important tools in the cold laboratory are micro-computed tomography (micro-CT), nature-identical snow production, and our in-house designed snow-breeders.

Based on the three-dimensional representation of snow, we can now calculate fundamental structural parameters as density variations at a spatial resolution of a few millimeters, e.g. revealing the finely layered structure of weak layers or of polar firn. In addition, the readily available data are used to calculate the correlation function in all 3D, which enables a deeper understanding of the interactions between structure and functional properties, e.g. for microwaves.

In addition, we are able to use the exact microstructure of snow for numerical simulations. Our own or adapted codes allow to calculate thermal conductivity, mechanical properties, and optical properties. Direct numerical simulation proves to be a highly valuable tool to understand the complexity of snow.

Our micro-CT is equipped with the ability to perform time-lapse tomography using so called snow-breeders. The snow breeder made the first in-situ time-lapse movie of metamorphosing snow under a temperature gradient possible.

Our developments don't stop at the microstructure. The quantification of snow properties at the larger scale of a snow profile or on a field requires new techniques to link the micro- to the macro-scale. For this purpose we developed the SnowMicroPen, a high-resolution penetrometer, which is able to discern different snow types using signal processing. Near-infrared photography has become a standard tool to quantify spatial variation of the specific surface area, and, concurrently, the equivalent optical grain size. Currently, we are developing new optical techniques which try to measure density and specific surface area at the same time.

 

Topics

Ganz links ein einzelner, verzweigter Schneestern, der unter einem Mikroskop fotografiert wurde. Das Bild in der Mitte zeigt ein Messraster auf dem mehrere Neuschneekristalle liegen. Ganz rechts eine dreidimensionale, stark vergrösserte Darstellung von Neuschnee, der in einem Computertomographen gescannt wurde.

Mechanical Properties

What do sounds such as the crunching of snow reveal about the microstructure of snow and the deformation properties of ice?

Optical Properties

Why is snow white and ice transparent? And why does snow turn darker the older it gets?

Picture gallery snow forms and snow structures

Microscopic and computer tomographic images offer a fascinating view of snow crystals and snow structures.

Schneemetamorphose im Computertomograph.

Snow metamorphisms

Snow metamorphism changes the structure of snow. We observe and measure these changes using a computed tomography (CT) scanner.

 
 

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