Snowmaking Facts

When nature doesn't cooperate by providing natural snow, snowmakers take over. Given water, electric or diesel energy and temperatures below 32°F (0°C) snowmakers can provide snow. Basically snow is small particles of ice. Snowmaking machines make snow by breaking water into small particles, cooling the water by causing them to move through cold air, nucleating the water particles and distributing the resulting snow on a surface.

Why don't people just sprinkle water to make snow? Water is a unique material, it expands when it freezes and it has high heat of fusion. Heat of fusion means that one can cool a pound of water say from 65°F (18.3°C) to 64°F (17.8°C) or 34°F (1.1°C) to 33°F (.6°C) by removing 1 BTU. But to convert one pound of liquid water at 32°F (0°C) from a liquid to one pound of ice at 32°F (0°C) requires the removal of 144 BTUs. Thus, a large amount of heat removal (cooling) is required.  

Also, water can be cooled well below 32°F (0°C) and still stay a liquid unless it is nucleated.  So a snowmaking machine a) breaks the water into small particles, b) cools the water to 32°F (0°C), c) removes the heat of fusion and d) nucleates.  Most requirements for snow require relatively large quantities of water, for example to cover an area of 100 meters by 50 meters with 20 centimetres of snow, one would need 1000 cubic meters of snow or 500 cubic meters of water. This is 500,000 litres of water. Thus, an excellent water supply and pressure is needed.

Humidity and Snowmaking

The lower the humidity, the more snow a system can make at a given temperature. Any system! This is because evaporation furnishes a significant part of the cooling in the snowmaking process. So, the lower the humidity, the more evaporation per unit of water, the more snow you can make. 

Going from 85% humidity to 40% humidity can sometimes double the amount of snow made even at the same temperature. Snowmakers therefore use Wet Bulb temperature to determine snow production. The Wet Bulb temperature is the lowest temperature a water droplet can reach in the atmosphere and takes into account both temperature and relative humidity.

Marginal Temperature and Snowmaking

Most snowmaking systems can make snow above -4°C Wet Bulb but above -2°C Wet Bulb they will do little more than dust the area.  Both fan gun and compressed air systems have seen conditions as high as 4°C Wet Bulb, but the humidity's must be extremely low. But to get "commercial" quantities without excessive energy consumption, temperatures below -2°C Wet Bulb are usually required. Snowtech has special snowmakers that have excellent snow production rates at marginal temperatures without excessive energy consumption.

If you do have consistent temperatures above -4°C, a larger snowmaking system may be necessary. Also, putting the snowmaking in the air will maximize the system's effectiveness (tower or boom mounts). This increases the hang time of the water particles in the cold air and more snow can be made.

SNOWMAKING AND SNOW QUALITY

Why Should I Make Snow? To get open, to stay open, to provide a base, to give the best skiing conditions possible and for cosmetics. In all these cases you are looking for volume, doing the job as quickly as possible and doing it at a minimum cost. In none of these instances does it make sense to make dry snow. 

If a snowmaker can make 2-3 times as much snow using the same amount of time and cost (and this is the case for wet snow compared to dry snow), profitable management requires that wet snow be made. Of course, we are talking about quality snow that meets the test described below.

What Is the Best Quality Snow?

According to most successful ski area operators, the best base snow is large particle wet snow not so wet as to discolour or bleed, but much wetter than fresh natural snow. The best surface snow may be a dry snow.

WHY? Natural snow will become more dense with age. So, most experienced snowmakers make snow that is like three-day-old natural snow. It lasts longer, holds up better, resists blowing away, grooms easier, and is the most energy efficient to make. Wetter snow is more efficient because more snow can be made with the same amount of equipment, the same amount of horsepower and the same number of people.

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