A few days ago, I was pressure washing my deck. Very interesting, I know, but wait before you leave, I understood something cool thanks to this mundane activity…
Pressure washing, essentially, consists in violently bouncing a water jet against dirt, transferring it momentum and pushing it away. You don’t want to be in the trajectory, because it's no fun being hit by a fast-moving mix of cold water and dirt. Usually, that's not going to happen to the person doing the washing, because the jet is directed away from them, and even when it bounces off the object being cleaned, it's still moving away.
So it's always a surprise when you get to a corner and end up covered in disgusting stuff from head to toe. The reason this is happening is because a corner has very interesting properties.
