Research into snow crystals started as early as the 17th century. In 1611 German scientist Johannes Kepler investigated the symmetry of the hexagonal structures and produced the first study into snowflakes. 400 years later, snow continues to fascinate us - whenever it falls.
What is snow?
Snow is the solid form of water. Snow crystals form when the temperature within a cloud is low enough. Simply put: supercooled moisture in the clouds freeze to form tiny ice crystals which join together in hexagonal (six-sided) structures. Depending on the temperature of the cloud, these crystals can form different types of snowflakes such as needles, dendrites (stars), flat plates or columns. The form also depends on the saturation of vapour in the cloud. Snow crystals form at the expense of water droplets (as the saturation vapour pressure over liquid water is greater than the saturation vapour pressure over ice and the vapour molecules move from high pressure to low pressure). But that’s enough physics. If the snow crystals are large and heavy enough, they will fall. And in Mayrhofen that means: it’s snowing!
Why is snow white?
Snow is made of water and would, therefore, usually be transparent to the human eye. So why is snow white? Snowflakes, like water, are essentially colourless. However, as snowflakes form, air is trapped between the branches of the snow crystals creating corners, points and surfaces. These act as countless tiny mirrors which reflect almost all light and make the snow translucent. Sunlight is white as it includes the total colour spectrum. For this reason fresh snow appears to be white.
From new snow to slush
- New snow still exhibits its crystal form and fell within the last 24 hours. The delicate ice crystals are still intact with their branches and spikes.
- Powder snow is very dry, light and fluffy snow which falls at low temperatures.
- Champagne-Powder is very soft and dry powder snow. As the name suggests, this type of snow is the very best for skiing. It usually occurs in the American Rocky Mountains where there is a low humidity.
- Moist snow is great for kids: the high moisture content makes it ideal for forming snowballs or building snowmen.
- Wet snow is very heavy and wet. Ski tourers will be familiar with the problem of wet snow sticking to the skins and making touring very hard work. Through the frequent melting and re-freezing of this type of snow, granular ‘Sulz’ snow is created which is not much better!
- Slush refers to a mixture of lumps of snow and water which do not hold together.
- Crust is a layer of snow on the surface of the snowpack which is stronger than the snow below. It is formed through a process of thawing and re-freezing of the surface snow. Below the hard crust, the snow remains powdery and dry. Also not ideal and even frustrating for skiiers.
- Firn is dense, granular snow which is at least a year old. The word comes from old German and means, simply and aptly, “old”. Firn snow can consolidate into glacial ice over the years. Another reason to love Firn snow: it is ideal for ski tours in the spring as it skis like powder snow.
By the way: Artificial snow or machine-made snow is formed when snow canons spray out water droplets at temperatures below minus four degrees. A very common type of snow in our ski area.