Snow is the focus of two halachic issues:
(1) The status of snow on Shabbat. Is snow muktseh? Are snowball fights permitted? What about shovelling snow off a pedestrian path? Can you build a snowman or snow fort?
(2) The ritual purity of snow. Can deep snow a be used as a mikve for immersion of utensils (or immersion of people who enjoy the cold)? Can snow be used to fill a regular mikve? In arid climates can artificial snow be used to fill a mikve?
Hebrew sources are available through the link. In class we will translate and explain these sources.