Like 'Rain' (which was featured on this weather series last week), you'd think we'd seen enough of snow this year, but BBC2 begs otherwise by bringing us this depiction of the snow flake. According to them, 'snow is the most fleeting and beautiful of elements which endlessly fascinates us'. Using rare footage, we're invited to journey into the microscopically small world of the snow crystal, finding out how a snowflake forms and why it is ALWAYS six-sided. The science of snow tests British Rail's claim that the snow that crippled their rolling stock in 1991 really was the 'wrong type of snow', and explains how a company is the world's largest producer of ice crystals. Narrated by Alex Norton.