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prevent this thermostat from properly functioning and therefore result in rapid loss of heat from the body. For this reason, the inflexible rule of ski mountaineering is that alcohol should never be drunk during or immediately previous to exposure to cold. As the body continues to get colder, the next reaction of the human system is to cut off most of the blood supply which normally goes to hands and feet and thus attempt to preserve normal temperature within the torso, where the vital parts of the body are situated. This can reduce the blood supply to the hands to as little as one-eighteenth of maximum. The danger of freezing of hands and feet as a result of such general chilling is obvious. In practice then, if danger of freezing the extremities exists, it is just as necessary for the skier to put on an extra sweater as dry mitts or socks; moreover, the sweater, unlike extra socks, cannot cramp circulation in the feet. Wind is as important as low temperature in producing chilling. A ten-mile-an-hour wind under some conditions is equivalent to a lowering of the external temperature 60°. On increase of wind velocity above ten miles per hour produces little additional cooling effect if wind-proof garments are worn. The problem of keeping warm is then primarily the providing of insulation from both wind and cold. To provide insulation from wind: A sheltered spot should be selected for camp. The tent should be thoroughly windproof. Becauseof the large amount of air that filters through ordinarytent walls, coated waterproof fabrics are warmer in heavywinds than the closest woven permeable cloths. In a heavy wind a snow cave is warmest becauseit alone can provide still air, although the snow is usuallyporous enough to allow adequate ventilation. |
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