This is a dry, warm winter, so barren and withered that it doesn't support the activity of skating or skiing. But today modern technologies can change this a bit. I upload some shots to show this.

This is the machine that is equipped with a large nozzle for spraying and sucking tap water.

Before, we saw pesticide-spraying nozzles working along the street but with a much smaller diameter, though a similar shape.

You need fluid dynamics ABC and heat transfer ABC and a bit thermodynamics at least to understand its mechanism.

This is different from the machines used previously in places such as a skiing hill for professionals, dedicated to those rich wolves. Now a great numberpublic parks in this city enjoy using the machine.