The friction of skis on snow appears to be affected by numerous factors, for example, speed, contact area, snow type (temperature, liquid-water content, hardness, texture), and ski properties (stiffness, thermal conductivity, base material, base roughness). Most of the knowledge concerning how friction varies with these factors is from laboratory measurements that do not describe the real skiing situation when skis move at high speed under a diversity of snow conditions. The purpose of this study was to demonstrate the influence of a wide range of natural snow and air conditions on the snow friction of a skier gliding down a test course at high speed.
A permanent 342-m-long test run was set up in the ski resort Gschwandtkopf in Seefeld (Tyrol) from January to March 1991. One experienced downhill skier performed 175 runs with the same equipment. The running time of the skier was taken. Maximum skiing speeds up to 30 m/s were reached. For each test run, air temperature and humidity as well as snow variables (snow temperature, liquid-water content, snow density, snow hardness, grain shape, and grain size) were measured.
The results are presented in scattergrams of running time plotted against the environmental variables. Attempts were made to explain the results in context with the basic theory of the friction of snow skis. Though single environmental variables correlate considerably with running time, the results indicate that variations in snow friction cannot be explained by single variables only. Liquid water content was found to be an important snow property. Different frictional processes may dominate on dry and wet snow, respectively. Limitations of the applied method for determining ski-snow friction are discussed.