Pfew, I tried to come up with a short description of the pitot-static system, to explain to everybody who’s confused about today’s strip what “alternate static air” really means. But during writing I found that I would either have to write a few paragraphs, or spend an hour to make it as concise as possible. Since I’m really under time pressure today, can somebody else maybe explain it in a few words?

Anyway, here’s the link to the relevant Wikipedia Article.