Guides

Base, mid, shell: the layering system that actually has sources

Outdoor clothing advice is mostly slogans. This is the version with sources: the three-layer system in the US National Park Service's own wording, the real evidence against cotton (dead-air collapse and water conducting heat 25 times faster than air — not 'cotton kills'), extra clothes as a Ten Essential, sun that strengthens by roughly 10 percent per 1,000 m, the one pack-size figure that survives verification (the Alpenverein's 30-40 L hut list), and the B0-B3 boot scale flagged for what it is: retail convention, not a standard.

How to read a mountain forecast (and when not to trust the app)