Frostbite
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Most of us north of the tropics know what it's like when winter takes a nip at our skin. It gets pale, numb, and tingly. When that happens, it's called frost-nip, the first sign of a more alarming sounding conditionfrostbite. I'm Dave Thurlow for the Mount Washington Observatory and this is the Weather Notebook.

Speaking of mountains, and frostbite, some of the world's most passionate mountain climbers have lost fingers, toes, hands and feet to frostbite. The damage happens because of two factors, and ice is only part of the story. When living tissue freezes up, ice crystals do form inside. But an even bigger problem is the effect of the cold on circulation. Small veins and capillaries can rupture and leak, and the blood may get sludgy enough to block the flow completely. This is why thawing out has to be done very gradually, so the thawed-out tissues get the blood they need.

What should you do if you're trapped in the cold and frostbite sets in even if your not on a mountain? One thing you don't want to do is to thaw yourself out only to freeze up again. Ideally you should minimize contact with any frostbitten areas and get to a hospital or clinic, where the frostbite can be warmed up under professional care. This involves a bath about the same temperature as a hot tub, or about 100 and 110 Fahrenheit. Dry heat or contact heat can burn the skin very easily. Only after the thaw-which can be very painful-can you tell whether the tissue will survive. Of course, the best strategy is prevention. Stay well bundled up. Do not underestimate the power of the. Please check out weathernotebook.org for frostbite safety and treatment tips.

Thanks today to Bob Henson, Sean Doucette and Subaru, the Beauty of All-Wheel Drive.