| Units The American Avalanche Association guidelines recommend use of the metric system because it is by far the easiest system to use for snow measurement, and it allows us to communicate with workers from other countries. It’s so easy to use that we are surprised that the US has still not completely changed over. For those still metrically disadvantaged, here are some ways to get over it: 1.) Buy and use the metric topo maps at the store, get a metric tape measure, read the Celsius side of your thermometer every morning, and you will soon find the units just as familiar and far more intuitive than the old ones. 2.) Remember that the metric system is based on the properties of water. Snow is water, so this works well for us. 3.) The system is based on the number ten, so calculations are easy. 4.) Snow density is measured in kilograms per cubic meter (kg/m3). A cubic centimeter of water weighs one gram. A liter of water is 1,000 cubic centimeters and weighs a kilogram. A cubic meter of water is 1,000 liters and weighs 1000 kilograms, which is roughly a ton. Its density is thus 1,000 kg/m3. In snow travelers’ terms, blower powder is in the 30-50 kg/m3 range, good floaty powder is around 100-120 kg/m3, settled old snow around 300 kg/m3, water-saturated snow 500 kg/m3, and glacier ice 800 kg/m3. 5.) For distance and elevation, we use meters, centimeters, and millimeters. Multiply meters by 3.281 for feet; centimeters by 2.54 for inches. Practically speaking, a meter is a big yard. A millimeter is a skinny sixteenth. A centimeter is about 3/8 inch. A 2x4 (inches) is a 5x10 (cm). A foot is about 30 cm. Measure and calibrate yourself to be sure, but knee-deep powder is about 50 cm on most adult males, and our belly buttons are about a meter off the ground. 6.) For temperature, degrees Celsius are 1.8 degrees Fahrenheit; about 2 degrees F, and 0 degrees C is the freezing point of pure water, or 32 degrees F. The handiest points to have in your memory are that 0°F is -18° C, -10C is +14°F, plus 10°C is +50°F, and minus 40° is the same in both systems. 7.) We measure wind speed in meters per second. Double that figure to get knots. 8.) Congratulations, you are now a citizen of the world in the 21st century! |