h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Why is it that, when it's really windy, it's difficult to breathe? I don't mean because of dust or what have you flying about--I mean literal difficulty getting air to enter the nose or mouth when you're facing into a headwind. You'd think it'd be more of a problem of air entering too quickly...

Good question, I've noticed that too. I guess this is due to Bernoulli's principle, which states that the sum of the potential and kinetic energy of a fluid flow is constant - therefore, as the speed of the fluid increases, its pressure must drop. (I find it hard to visualise this happening in free-space though, perhaps someone else can elucidate). In a high wind there would be an area of low pressure at your nostrils, making it seem harder for your lungs (which are used to 'normal' air pressure) to suck in.

That makes sense... Except then why would turning your head just a little work? (Or, in my case, work once hair has been clawed out of my face--waist-length hair does a great job of wrapping a head when it's allowed!)