Up to certain sub-zero temperatures, the ice is indeed very slippery. However, skating, for example, on deep-frozen water down to -30 or -40 degrees Celsius can become a chore.
This phenomenon has its physical explanation. At low rigorous temperatures, the friction of the blades of the skates – or of the skis – with the ice generates enough heat for it to melt momentarily, or that it originates a thin layer of liquid water that acts as a lubricant and allows that the skates slide with tremendous ease. However, in the case of ultracooled ice , the pressure that the skater exerts on the frozen surface is not enough to allow the formation of a liquid film and it is precisely for this reason that sliding becomes a complicated task.
