> Have you ever experienced Humid -40C air? It doesn't happen. > I've had very humid -25C air in Alaska You haven't had very humid -25C air, in an absolute se

> Have you ever experienced Humid -40C air? It doesn't happen. > I've had very humid -25C air in Alaska You haven't had very humid -25C air, in an absolute sense. Take a look at a vapour pressure calculator (https://www.omnicalculator.com/chemistry/vapour-pressure-of-water https://www.omnicalculator.com/chemistry/vapour-pressure-of-...): the vapour pressure of water at -25C is about 63 Pa, but about 13 Pascals at -40C. The difference of 50 Pa is trivial compared to the ~100,000 Pa pressure of air at sea level. Once you're below 0C, there just isn't enough water around in a vapour (or suspended) phase to have much impact. A Globe and Mail article from 2016 discussed this phenomenon (https://www.theglobeandmail.com/life/health-and-fitness/fitness/is-damp-cold-really-the-worst/article28346087/ https://www.theglobeandmail.com/life/health-and-fitness/fitn...). Its conclusions were still tentative, but the strongest correlate of the effect seemed to be cloud cover, where bright sunlight felt warmer despite colder air temperatures.