While I was filling in for John Brown on KTRS/St. Louis yesterday, I was talking with his co-host Trish Gazall, who is about to embark on her first ski vacation in Aspen, Colorado. I'm not a skier -- having tried it a couple of times as a kid and discovering that gravity was not my friend -- but I gave her some silly advice about the tow-rope on the bunny hill and some other things. Then someone else in the studio reminded her to take plenty of sun screen, because on the mountain, she'd be closer to the sun.
I paused as this idea rattled around inside my head for a moment. Then I pointed out that The Earth is approximately 93,000,000 miles from The Sun. Getting a mile closer is statistically insignificant. You're not going to get more sunburned because you've lessened the distance to 92,999,999 miles.
The reason skiers get sunburned is not because of their heightened proximity to The Sun, but because they don't think they need UV protection in the winter. They're used to lathering up on a hot summer day around the pool, not when it's below zero and the rest of their body is covered in GoreTex.
On the other hand, if Trish has as much skill on the slopes as I once did, she won't have to worry about the intensity of the sun -- because she'll be inside the lodge, enjoying a nice warm beverage. I hope she doesn't get too close to the cup.
Update 1/15/10 @ 8:52am...Several readers, including Dave Aronson and Rob Fugina, wrote to remind me that skiers also get sunburned for another reason -- the sun reflecting off the snow. It's the same reason you can go "snowblind."
Update 1/15/10 @ 11:19am...Elvis writes, "Elevation matters because the atmosphere up there is thinner. That's similar to the reason why it is hotter in the northern hemisphere in July (when the sun's rays pass the most direct angle through the atmosphere) than December (when the sun's rays pass through the atmosphere at a shallow angle), even though the earth is slightly farther away from the sun in July. At a given solar angle, the UV rays that cause sunburn are relatively more intense at high elevation (or altitude) than at sea level. Astronauts, pilots and mountain climbers are well aware of this fact."