Snow is a type of precipitation in the form of crystalline water ice, consisting of a multitude of Snowflakes that fall from clouds. The process of precipitation is called Snowfall.Since Snow is composed of small ice particles, it is a granular material. It has an open and therefore soft structure, unless packed by external pressure. The METAR code for Snow is SN.Snow remains on the ground until it melts or sublimes. In colder climates this results in Snow lying on the ground all winter; when the Snow does not all melt in the summer they become glaciers.This is often called Snowpack, especially when it does persist a long time. The deepest Snowpacks occur in mountainous regions. It is influenced by temperature and wind events which determine melting, accumulation and wind erosion.