A:Glasses that don't fog up can be tough to find. It's an issue for me during winter mountain biking, where we'll sometimes stop to talk and reconnoiter, and in 45 seconds I'm blind. That's especially bad when we're biking at night, and the light scatter from the leadlight gets on the condensation!
Thing is, there are lots of variables, mainly weather-driven. Condensation is all about the dew point—the temperature that makes moisture condense out of the air. If conditions are right, it takes just seconds for the moist, warm air flowing off your face to hit the cold frames and start to condense. At other times, there might not be any condensation.
Anyway, in terms of which glasses are more condensation-resistant, look for something with good airflow behind the lenses. That might eliminate full-wrap sunglasses. The simply trap too much air. Also look for glasses with vents, which can help move air, although once you stop they offer less value.
Some candidates might include the Oakley Jawbones, which are kinda dear at $200 (to start), but they do have interchangeable vented lenses and a design that is close-fitting but not glued to your skin. Excellent optics, light and tough frame. I'm also impressed by impressed by both the function and price of the Ryders Sprints ($40). These are cycling-style glasses that offer good eye protection but aren't fully wrap-around. They have anti-slip pads on the nose, vented brown polycarbonate lenses, and light frames. Worth a look. The Julbo Trail ($160) are all-purpose sport glasses have photochromic lenses, so they adapt to different light conditions, which is handy when skiing from sun into shade. Good venting, excellent optics, rugged frames, and anti-fog coating on the lenses. And Smith always offers good value in sunglasses, well-designed and high-end, but not wildly expensive. The Parallels ($129 ) offer polarized lenses—great for snow—and a sporty design that should vent well. Another polarized-lens pair, Zeal's Tenacity PPX ($150) have somewhat blocky design that gives you good eye protection but stands off of the skin a bit. And they're photochromic!