Amateur Aerodynamics

In aerodynamics engineering, we talk about pressure a lot . But what is pressure anyway? It's something we're all familiar with in our everyday lived experience: your ears "popping" when you drive up a mountain due to the pressure change with altitude; feeling drained or tired after a long flight in a cabin at a different pressure than what you're used to; sticking your hand out a car window and feeling the "push" of the air backward. You might even remember from a physics or chemistry course that pressure arises from the molecules in a gas zipping around, occasionally bouncing off a surface, and that the faster they move, the greater is the pressure the gas exerts. "Movement" implies velocity alone, but of course the number and mass of these molecules also matters: more mass, greater pressure. Mass and velocity multiplied give momentum , and pressure arises from the transfer of momentum between molecules in a gas and any surface in contact wit...