Does photogrey lenses get darker in cold or hot weather?

Question

Does photogrey lenses get darker in cold or hot weather?

Answer 1

It was more marked on older forms of photochromic lenses, but all the ones I know still darken more easily when they are cold, and lighten more easily when warm...

Skiing was always the ideal setting: go out in the light and cold: fast darken, come inside where it's dim and warm: fast lighten.

Answer 2

Nope, they react to the sun's UV rays, which is why they aren't great for driving since the rays are blocked by the car.