The snow covers the ground in the same way frozen ice crystals would from a storm cloud. The trick and the artistry come in the mixing of water and air under pressure, and divining the perfect weather conditions for snowmaking. Once mounds of snow have been created on the hill, groomers weigh in to flatten the piles and smooth the surface. Ten inches of natural snow, when packed, usually adds only one inch of snow to a ski slopes' base. Four to five times as much snow can be made when the temperatures are in the low 20s.
Humidity is a factor.
The lower the humidity, the better it is for making snow. If you add temperature to humidity the sum should equal less than 100 for favorable snowmaking weather. Little or no wind is preferred. In wind, the snow tends to drift off the slope and into nearby trees. Next time you are out there enjoying the snow at your favorite resort, pause for a minute and reflect on what it takes to prepare that hill for skiing or riding.