Quantification of the hand hardness test

Abstract

AbstractSnow hardness is the resistance to penetration. It can be measured by the Swiss rammsonde or estimated by the hand hardness test. According to the International Classification of Seasonal Snow on the Ground (ICSSG), snow hardness is divided into five levels (without ice). However, the hand test is subjective and provides only an index value of snow hardness. The main objective of this study was to determine the hardness using an alternative method which can be applied in the same way as the hand test and which can deliver accurate data. In this study the conventional hand hardness test was used; additionally, a digital force gauge (push-pull gauge) was applied where the hardness was measured horizontally (for comparison with the hand hardness test). The push-pull gauge could be provided with five different attachments. The size and design of each attachment corresponded to the equivalent application of the hand hardness test (fist, four fingers, one finger, pencil, knife). This paper indicates how snow hardness measured by hand is related to snow hardness measured with the push-pull gauge. Moreover, the variability of the hardness, both vertical and horizontal, is demonstrated. The results show agreement with the ICSSG for hand hardness indices 3, 4 and 5; for hand hardness indices 1 and 2, the range indicated by the ICSSG is below the lower quartile of the measurements.