For skiing in Australia I'll usually wear a long sleeve tshirt under a normal tshirt, my ski pants and jacket and maybe a scarf. In Japan the temperatures are about 20 degrees colder than your average Australian ski day (the max temperature today was -19 degrees celsius, with the windchill making it -29). This means a few more layers are required. In fact some mornings I think the pile of clothes I'm not wearing is smaller than the pile I am planning to put on! It all feels a bit ridiculous so I thought I'd draw some helpful diagrams to explain how to layer for sub-zero temperatures. I hope these pics work because blogging from an iPod takes forever!
Long sleeve tshirt
Another wool jumper
Circle scarf (looped around neck and over head)
Ninja face mask
Skis & poles