To ensure that an alpine ski race surface is hard, uniform, and resistant, race organizers often use water to ice up the snow. There are a few ways to do this. One is to just use water cannons, using the groomer to work the treated top layer of snow into the surface. The other way, which seems a bit more methodical and almost peaceful, is to use an injection spray bar.
These spray bars inject water into the snow with cone-shaped nozzles, creating thousands of small holes in the slope and filling them with water as organizers work it down the mountain. When the bar work is done, a groomer passes over to mill the section and the cold weather does the rest.
With water cannons, the groomer has to work in conjunction with the trail crew, churning up the top layer before water is laid down and working the trail again once it’s been sprayed. With the spray bar, the groomer just needs to wait until the work is done to finalize it with a mill.