Of all the disasters that can befall a traveler in regions of snow and ice, the main adversaries would seem to be cold, high wind and avalanches.
But there is a silent and apparently benign menace of a winter wonderland: the color white.One result of overexposure to a peaceful expanse of dazzling, feathery snow or enchanting castles of ice is snow-blindness.
Ultraviolet rays reflected from snow or ice, can cause a temporary loss of sight.
Normally the human eye can absorb this light, but under conditions of extreme exposure the eye's protective mechanism overloads, and an abnormal intolerance of light develops.
Victims have described the landscape as appearing pink and then red, and they fell an intense pain as though a handful of sand had been thrown in their eyes.
Snow-blindness does clear up after rest away from intense light, but it can be easily prevented by wearing dark glasses whenever exposed to prolonged white glare.
A companion condition to snow-blindness can occur on a warm, sunny day in a desert or at a beach or, as was experienced by one of the writers, at Whit Sands National Monument.
For accuracy it is called sunblindness.
The writers were entering the Monument when the driver instantly experienced a sharp pain in his eyes. He stopped the car abruptly and closed his burning, watery eyes.
The intense glare of the white sand had burned the conjunctiva of his eyes, and it was necessary for him to find shade and rest briefly.
Fortunately, one of the party contributed his dark glasses, and the adventure over cotton-soft dunes continued. Later, he camped in White Sands while conducting a week-long geologic survey and suffered no further sunblindness.
At times the polar regions are converted into a realm of fantasy where the senses become completely befuddled by the strange actions of cold air and drastic extremes in temperature. Light rays may bounce between the ice and low clouds, creating an opalescence called "whiteout." Every landmark is literally wiped out. To separate earth and sky and to determine where or if there is a horizon is impossible. As one veteran of whiteout described the experience, "It's like wandering around inside a ping-pong ball." This optical illusion can occur wherever snow covers large, flat areas. Although conceivably a worldwide phenomenon, whiteout is most common in the Antarctic and Arctic, areas where snow and ice are perennial. In scientific expeditions into the Antarctic, whiteouts are a much feared weathered phenomenon.
Although whiteouts can be caused by fog, fine precipitation or blowing snow, they occur most often in clear, calm air under an unbroken layer of heavy, low-lying clouds that stretch from horizon to horizon. The uniform overcast diffuses the daylight and causes it to reflect between cloud and snow, thus obliterating all distinction between earth and sky. The horizon disappears, and nothing but white remains. In the unbroken whiteness, judging depth or distance becomes impossible: What appears to be an oil drum 100 yards away may turn out to be a can of beans at arm's length -- or vice versa. All shadows and surface details disappear in the unrelieved whiteness. Walking is quite hazardous, since small holes and large crevasses are indistinguishable from the surrounding snow. A single step can result in a crippling injury or fatal fall.
Vertigo, characterized by dizziness, disorientation and disturbed balance, is also common during whiteout, so any sudden movement can become quite dangerous.
With no horizon to serve as a visual reference, skiers often fall down.
Some are so confused that they just lie where they land (actually a good idea).
Drivers of tractors and snowmobiles often topple from their vehicles and pilots, with no perception of depth, fly their planes headlong into the ground.
In 1958 at Ellsworth Base, Antarctica, a helicopter pilot caught in a sudden whiteout lost his bearings. Unable to distinguish just where the ground was, he tried to land the chopper at a 90-degree angle.
The first thing that touched the ground was the nose of the ship, and it exploded.
A rescue pilot almost joined the victim when his helicopter, which he presumed was flying level, bumped the ground at a steep angle.
The pilot escaped from his demolished aircraft, but no one was able to rescue him until the whiteout had run its course.
A standard practice for an airborne helicopter during a whiteout is to throw out some dark object on a line to help the pilot determine whether the craft is flying 20 feet above the ground surface -- or 20 inches.
Antarctic veterans have long concluded that the only sensible plan for whiteout survival while traveling on the ground is just to sit down and wait it out.
Sooner or later the light will return to normal, and the details of the landscape will once again become distinguishable.
The horizon will reappear to separate the sky from the earth, and travel can be resumed safely.
Phil and Nancy Seff are the authors of several science books, including "Our Fascinating Earth." Their column runs regularly in the Deseret News Science/Technology section.