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Show D H.lltop T.mes WINTER SAFETY Dec. 13, 1991 1T COOLING POA OF WIND "7l2Td (jndaf tdm condttorti) 53 43 30 70 10 0 SO 43 30 20 10 0 4 37 27 11 10 40 28 18 4 15 38 77 9 -- 20 32 18 4 -- 10 75 30 18 0 30 28 13 3$ 27 II 40 28 10 clr fKwi property cioltod pmon) MuimwMi dnftr of faht mom of Mcuriiy. Csim S Two enemies await the unwary in the winter. Frostbite and hypothermia take their toll each year. Frostbite is simply the freezing of exposed flesh. When it s severe, you lose the flesh. Hypothermia is a bit more complicated, but just as sneaky. Anytime you travel into or over a cold area, you're a potential victim for this dangerous duo. Frostbite occurs only at sub freezing temperatures and isn't usually fatal. Give it a chance, though, and it will take off your fingers, toes or ears just as surely as a power mower but more painfully. On exposed flesh, frostbite is easy to spot. Anytime you are outside in freezing weather you should check for it periodically. Look for waxy, g skin. The area will feel numb, too, so you're not likely to feel it. If you spot one of these areas early, it probably will be just in the frostnip stage. Prompt action will limit your injury to something like a bad sunburn. If you don't catch it right away, it will progress rapidly, and serious injury will result. HIZH EXPRESSED AS AN EQUIVALENT TEMPERATURE ON EXPOSED 0mphtov wMd tffact. 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To warm toes without being a contortionist, place them against someone else's stomach a real test of friendship. Cheeks, noses, or ears are easy to warm by just covering them with the palm of your hand for a few minutes. Don't rub a frostbitten area, or you'll really cause damage. Prevention Preventing frostbite is a lot easier. Frostbite is not normally an affliction of survival. It usually strikes when you're having fun. To prevent frostbite, keep your circulation up. Any time your toes get cold, then seem to warm up for no reason, check them. They're probably getting numb, and that means frostbite. Pull off your boots and check for white spots on your toes or heels. Look out for wind. Moving air chills and freezes exposed skin much faster than still air. For example, suppose you jump on your snowmobile on a bright, comfortable, day. Skimming over the snow at 30 miles per hour, your face, ears and hands are chilled by an equivalent temperature of 10 degrees below zero. You can get frostbite in 25-degr- er develop judgment about the presence and degree of avalanche danger. Most accidents are caused by slab avalanches large slabs or angular blocks of snow begin to slide all at once. Many times the victims have triggered the avalanche themselves. Their weight on the stressed snow slab is enough to break the fragile bonds that hold it to the slope. Terrain factors Slope steepness Avalanches are most common on slopes of 30 to 45 ee minutes. It's fairly easy to prevent frostbite just cover up exposed areas, keep your feet warm, and watch for numb or white spots. Hypothermia But what about the real killer hypothermia? Frostbite attacks extremities, but hypothermia chills your body core. It's a little more complicated than frostbite, too. Your body converts food to heat and energy. You lose most of the heat to the air around you, and your thermostat is set at 98.6 degrees Fahrenheit. Lose g slopes are danin on sunny days. and gerous spring Leeward slopes are dangerous because snows add depth and g create hard, wind slabs. Windward slopes have less snow, it is compacted, and usually strong enough to resist movement. Ground cover Large rocks, trees and heavy brush help anchor the snow, but avalanches can start even among trees. Smooth, grassy slopes are more South-facin- g d Information in the above article courtesy of Aerospace Safety Magazine. aren't deposited late in the storm. Rapid changes in G) weather conditions cause snowpack Wind ad- justments that may affect stability. There- ' Safest n" " v fore, be alert to weather changes. Dangerous Wind Sustained winds at or above 15 miles per hour rapidly increase the danger of an avalanche r v J Usual,y saferoute hollow-soundin- dangerous. Storms About 80 percent of all avalanches occur during, and shortly after, storms. Snow falling at one or more inches per hour increases danger. Crystal types Observe general types. Small pellet-lik- e crystals result in more dangerous conditions than crystals. snow-cryst- al star-shape- Weather factors Temperature Snow persists in an unstable condition under cold temperatures. It will settle and stabilize rapidly when temperatures are near, or just above, freezing. Storms starting with low temperatures and dry snow, followed by rising Snow is deposited on leeward slope and forms slabs. heat-savin- g at the right temperature. fun; avalanches is you body's mechanisms. Stay dry you lose heat much faster if you get wet or even get overheated and sweat. Cover your head. Avoid wind. Find or make a shelter. Warm up with a fire. Wear appropriate clothing layered so you can take some off or put some on to keep your body it can strike fast. If your body gets too cold, your thermostat will shut off most of the blood flow to your hands and feet to save all possible heat for your vital organs. Slope profile Dangerous slab avalanches are more likely to occur on convex slopes, but may also occur on concave slopes. Short slopes may be as dangerous as long slopes. Slope aspect Snow on north-facinslopes is more likely to slide in mid- wind-deposite- short-circuit- Hypothermia isn't something that happens to you while you're enjoying winter sports. But if something prevents you from going inside to warm up, degrees (60 to 100 percent), but large avalanches can occur on slopes ranging from 25 to 60 degrees. winter. you'll return. Carry some signals. Eat regularly and well. s No booze it too much heat, so your body can't keep up, and your temperature starts to drop. That's hypothermia. If your temperature falls about 20 degrees you've had it. The whole machine shuts off. Recreation in snow Avalanches pose a great risk to anyone using the back country for any reason during the winter. Snow avalanches are complex natural phenomena. Experts do not fully understand all the causes. It is difficult to predict avalanche conditions with certainty. But these guidelines will help a thinking observ- You'll shiver uncontrollably as your body exercises involuntarily to speed up heat production. Unless you start conserving body heat, those internal organs slow down and finally quit functioning. As your body core begins to cool, your shivering stops, your muscles get stiff, your coordination goes to pot, and you're completely beat. The worst symptom, though, is that you just don't even want to help yourself. There's no need to be beaten by hypothermia. Just knowing what it is-- will help you whip it. When you fly, hike, hunt, fish, snowmobile, or drive around a sparsely populated area in winter, be ready for hypothermia. Always: Tell someone where you are going and when temperatures, are more likely to cause avalanches. The dry snow at the start forms a poor bond and has insufficient strength to support the heavier snow d General observations Look for signs of recent avalanche activity and old slide paths; listen for sounds and cracks; be alert to snow conditions. Old slide "cartwheels" roll down the slope. Sounds and cracks If the snow sounds hollow, particularly on a leeward slope, conditions are probably dangerous. If the snow cracks and the cracks continue to form, this indicates slab avalanche danger is high. paths Generally avalanches occur in the same areas. Watch for avalanche paths. Look for small trees, with limbs pushed-ove- r off. broken Avoid steep, open gullies, and slopes. Beware when snowballs or ! 1 New snow, old snow Be alert to dangerous conditions with one foot or more of new snow. The nature of the old snow surface is important. Rough surfaces favor stability; smooth surfaces, such as sun crusts, are less sta- ble. A loose, underlying snow layer is more dangerous than a compacted one. Check the underlying snow laver with a ski pole, ski or rod. Information courtesy of the U.S. Department of Agriculture. |