Demystifying the Rain Shell: Hydrostatic Head and MVTR
We’ve all experienced that sinking feeling when cold raindrops start to seep through our rain jacket. I thought this was waterproof? Why am I getting wet? What does waterproof even mean? Aren’t all rain jackets waterproof? If that’s the case, why are some ten times as expensive as others? The answer to each of those questions may be the same: hydrostatic head.