What is the purpose for snow?

In a spiritual sense: Snow is one of God's instruments for assisting us in the maintenance of our spiritual growth.

Or it can be: Snow serves as an insulating blanket, lessening to some extent the extremes of temperature fluctuation to which the soil is subjected, but it also brings about a rapid cooling of the overlying atmosphere, giving rise to polar air masses. Snow lessens loss of water by dormant plants.

It doesn't have one. No more than any other natural phenomena do. They just are. Purpose is something that implies a use or intent of some sort. Most human activities have purpose (whether we like the purpose or not), and most animal actions do too. But tides just flow because they're made to by external objects that have no interest in the flowing. An igloo is made of snow, but the purpose there lies in the building and inhabiting rather than in the snow. A wind has no purpose, but hoisting a sail does.

Balloo, you couldn't have put it better. Snow is merely a form of water which exists in a crystaline form at certain temperatures and pressures, that's all!

Slartybartfast first tried it as an experiment in Norway while he was designing the fjords. Its purpose was decorative and proved so successful it has been launched in various parts of the world many times since.

Snow is a type of precipitation in the form of crystalline water ice, consisting of a multitude of snowflakes that fall from clouds.

Precipitation is a major component of the hydrologic cycle, and is responsible for depositing most of the fresh water on the planet.

https://en.wikipedia.org/wiki/Precipitation_%28meteorology%29

https://en.wikipedia.org/wiki/Snow