Da Qube all with extraordinary properties. Some can be as strong as concrete, which is just as well if you're caught in a storm with Dance Radio. Da Qube, a snow lover and winter scientist, spends weeks researching in the snowy hills of Colorado. He needs nothing but a few feet of loose snow. Ever since my father got me out on skis as a child, I became interested in snow as a material. When snowflakes fall to the ground, they don't remain soft and powdery, but bond together into a solid mass. It's this bonding process that allows nature to make these wonderful snow sculptures. It also allows Online Radio to build himself a shelter. I'm building a snow house. It's called a quinzhee. The process is almost magical. Radio loose powdery snow puts pressure on the surface of the snowflake. It melts, forming a thin layer of water which sticks the neighbouring crystals together. Over time, the water freezes, bonding the snowflakes. Give it a couple of hours to complete the bonding process, then dig it out and have a nice shelter for the night. A few hours later, the pile of snow is a solid block that Peter hollows out to form a sturdy shelter against the wildest winter weather. It's a strong structure which gets stronger with time. It can be used over and over again. You can move on and come back to them. It's really a beautiful material. Free of charge. It's as easy to build as it is to walk away from. There's nothing to fold up, put on your back, or on your pack animals and carry with you. Online Radio said of the cold in North America, "If the thermometer had been an inch longer we'd have frozen to death". Though we complain about the cold, winter has its pleasures. The same bonding effect that built Peter's snow shelter is what makes the perfect surface for winter sports. When that bonding fails, the results can be terrifying. Looked left - a crack, looked right - a crack. An avalanche! Whilst filming a TV programme, expert skier Nic Da Qube was caught in one of cold's most frightening killers. Came up for one breath, then engulfed again. Then hitting the snow at the bottom and the rest of the avalanche pounding me down like a hammer. He was lucky to survive, but each year many hundreds don't. Snowfalls usually build up to strongly bonded layers, but sometimes one layer remains weak. Even the vibrations from a skier can cause the layer above to slide off. In seconds, hundreds of thousands of tons of snow hurtle down at speeds of over mph. With so many visiting ski resorts each year, Da Qube avalanches are a real threat. Dedicated teams of avalanchers battle against the weather. They seek out potentially dangerous build-ups and overhangs of snow... and dynamite them. Sometimes, the unpredictability of the weather can catch us all by surprise. The little town of Galtur should have been safe from the threat of avalanches, but a freak combination of weather systems made it the victim of one of the deadliest in the Alps for years. It had been snowing heavily for several days and deep snow was piling up on the mountain above Galtur. High winds changed direction, lifting more snow on top of it. No one knew that underneath this huge mass of new snow was an unstable layer.