In reply to FreshSlate: It's not about heat, but exposure to sun radiation. It can be -20C on the mountain, but if you are close to equator and it's clear sky with sun is in zenith you can get nasty sun burns reasonably fast. Speaking from personal experience as skier.
Lycra and nylon are much better to protect from sun radiation. They are UPF 50+ except ones you can see boobs throw. Cotton t-shirt is normally at UPF 25 - 50 depending how thick it is.
In reply to nutme: Sorry you're right, I mean sunny not hot, the picture looking like Kalymnos (Greece, Sea level) sent me straight to that word. Besides, who's only wearing that hoody at -20? Im sure your insultation on a mountain is providing much more protection anyway.
Okay so lets get off the mountain, so if a cotton T-shirt is 25 upf which blocks 96% of the sun, and 50 upf hoody sold by OR blocks 98% of the sun, who gives a shit?
I remember coming back from the Alps years ago and being surprised to find my arms and torso tanned. I had been wearing a helly all the time while I was walking around on glaciers, but it would seem a thin layer of knitted polypropylene doesn't stop much UV.
Press Release Arc'teryx Alpine Academy returns to Chamonix-Mont-Blanc - July 4 – July 7, 2024
Podcast Mountain Air - 14. Dougie Baird, Mountain Path Builder
Fri Night Vid Ethan Pringle on one of Portugal's Hardest Sport Climb
In this week's Friday Night Video, we follow Ethan Pringle to the 'not-yet-popular' but world-class sport crag of Meio Mango in Portugal. In the film, Ethan attempts one of the country's hardest lines, Filipinos, which was first...