Clinging to a cliff in the middle of a snowstorm is an educational experience: It's amazing how attentive you can be when a false step might be fatal. I discovered this 13,160 feet up on Wyoming's Grand Teton, where my climbing guide, Rod Newcomb, and I were perched on a granite ledge in a tight notch called the Upper Saddle. Rod was rapidly expanding my vocabulary of extreme weather terms—"graupel," for the sharp, tiny pellets of snow whipping into our eyes; "rime ice," for the treacherous invisible layer forming on the rocks beneath our feet; "ground shocks," for the near-lethal jolts of electricity that can surge through the mountain after lightning strikes. Since this was my first ever technical climb, I nodded solemnly like an acolyte before a Buddhist monk. I figured this was important stuff—particularly the part about lightning charging through the boulder I was leaning against.

"You might want to move away from that," Rod suggested. "I've had more nasty shocks up here than I care to remember."

With over 400 Grand Teton ascents under his harness, Rod, a 73-year-old climbing legend with Exum Mountain Guides, spoke with the voice of experience. I shuffled to the edge of the precipice, thankful that a billowing fog concealed the 2,000-foot drop just inches from my toes. The good news, Rod went on, was that there was not a breath of wind. The temperature might be well below freezing, but on the Grand it usually blew a gale at this altitude.

"If there was any breeze right now," he said, "we'd be in pretty bad shape."

I kept my opinion about our shape to myself and fixed my eyes on the swirling clouds below. As if on cue, they parted and the Grand's Western Spur momentarily emerged from the fog, stretching out like the spine of some prehistoric creature. Wiping the graupel from my eyes, I reminded myself that I was participating in a great tradition: America's national parks were created so that people like me could get into situations like this.