Weather Whys; Snow Albedo

This is weather-wise, experienced skiers know there are more hazards in the snow than simply the possibility of a broken leg. When the sun glints off fresh, white snow, it can produce sunburns to rival any at the beach in July, and the bright light can produce headaches and even temporary eye damage. atmospheric scientists would say those effects occur because snow has a high albedo. The albedo of a substance is the percentage of incoming solar radiation it reflects. Some substances like dark soil absorb most of the radiation that hits them, and so are said to have a low albedo. But snow reflects up to 95% of incoming solar radiation, and so has a very high albedo. When the sunlight shines off the snow, the reflected rays go in all directions, and it's a good bet any exposed skin will catch a fair number of rays. So the combination of reflected and incoming sunlight can cause a painful burn.

In fact, that burn may be worse than one a person would develop from similar exposure at the beach. After all, beach sand reflects at most only about half of its incoming radiation. The other part of the energy goes to raise the temperature of the sand to foot-singing levels, but that does mean sand reflects less sunlight than snow. Now the smart skier or snowbuff applies liberal doses of sunscreen to exposed skin, but it's a little harder to protect the eyes. The glare from fresh snow can produce headaches, as well as a temporary visual impairment called snow blindness. And in recent years, scientists have determined that ultraviolet radiation from the sun can cause additional damage to the eyes. So a proper pair of sunglasses or ski goggles is a must. Weatherwise is made possible by a grant from the National Science Foundation. But weatherwise, I'm Drew Barlow.