Snow is a characteristic symbol of winter, and the one that makes possible diverse mountain activities. However, the process of the snow formation is slow, and special conditions have to be matched for this process to take place.
The formation of snow
For snow to form two things are needed:
- An atmospheric temperature below the freezing point of water, as water has to be converted into ice.
- And sufficient air humidity, as water has to be present for the formation of snow.
The water vapour that converts into ice will be formed around small particles, as dust or sand grains, to form tiny ice crystals. As time goes on, the ice crystals continue to grow as more water vapour freezes on their surface.
Once ice crystals have grown big enough, they are considered snowflakes. The latter are big and heavy enough to fall from the cloud and reach the ground.
“Wet” and “dry” snow
The size and composition of a snowflake depend on the number of crystals that have grouped together, and this is determined by the temperature of the air:
- If snowflakes go through “warm” air (slightly above the 0ºC), they will start melting by the edges, and sticking with other snowflakes or other ice particles, to become big and heavy snowflakes. This creates “wet” snow, which sticks easily and is good for making snowmen.
- On the contrary, the snowflakes that fall through dry and cold air, will be powdery snowflakes that don’t stick together. This type of snow is the most appreciated for ski activities.