Extreme Environment
Thin air evaporates sweat faster, not slower. At 8,000 m the garment is rarely the limit — the climber's water is.
— g/h
Sweat the garment can move at these conditions
A capacity ratio comfortably above one is not good news here — it means the climber is losing water at the full metabolic rate into air that will take all of it, and respiratory loss at altitude adds substantially more on top. The pressure correction applies only to the air-layer share of Ret; a membrane's own resistance is a material property and does not change with altitude, so that split has to be right or the answer is not. The model also assumes a fully wetted skin at steady state and ignores condensation and freezing within the insulation, which is the actual failure mode of multi-day cold-weather clothing. High-altitude physiology is medical territory and this is a clothing calculation, not physiological guidance.
High-Altitude Suit Hypobaric Moisture Transport — free, with the formula and a worked example, at Textile School.