LiveScience: For snow to form, there has to be stuff in the atmosphere microbes, specks of dust for water molecules to freeze on and then form ice crystals. But in the pristine Arctic, where the atmosphere is very clean and the ocean is covered in ice, it can sometimes paradoxically snow for days on end. Researchers at Michigan Technological University in Houghton set out to investigate the mystery of where snow in the Arctic comes from, and how it can fall so persistently in the region. "Within a few...