Skiers get suntanned faster on new powder snow than on old, wet snow, which absorbs far more of the sun’s ultraviolet rays, according to Norwegian researchers.
About 90 percent of the ultraviolet rays that cause suntans and sunburns reflect off the crystals in dry, new snow against just 10 to 20 percent from wet snow.
“We get brown, or burned, almost twice as fast on dry new snow as on wet, heavy snow,” said Berit Kjeldstad, a physics professor at the Norwegian University of Science and Technology.
She said surroundings were often as important as whether it was sunny or cloudy for anyone seeking a tan.
On a sunny day at the beach, about half the ultraviolet rays come direct from the sun and most of the rest is reflected from a wide sky, and only little from sand or water.
In an article published on the Norwegian universities’ research Web site, Kjeldstad said it was a common misconception that water and slushy snow are good reflectors of ultraviolet rays.
“Many people believe that water reflects a lot, because we can quickly go brown sunbathing by the sea. This is wrong. The percentage (of ultraviolet) reflected by water is 6 to 8 percent, about as much as by a green field,” she said.
Revision date: July 4, 2011
Last revised: by Andrew G. Epstein, M.D.