Clouds
The miracle of flight is, in many ways, actually a miracle of fluid dynamics. And even though you can't see the wind through an airplane window, I feel like clouds can give you a little bit of a glimpse into that world. They help to expose the otherwise-invisible workings of the world around us.
So, for instance, a running turbofan creates a region of low-pressure air ahead of it, which can cause interesting flow phenomena when interacting with nearby surfaces. Those streamlines are usually invisible, but in the right conditions on a damp taxiway, a vortex appears (as in the bottom-right of the picture). That vortex is always there, of course. But it's the cloud of condensation that makes it visible, and that reinforces the wonder of modern aircraft.
So, for instance, a running turbofan creates a region of low-pressure air ahead of it, which can cause interesting flow phenomena when interacting with nearby surfaces. Those streamlines are usually invisible, but in the right conditions on a damp taxiway, a vortex appears (as in the bottom-right of the picture). That vortex is always there, of course. But it's the cloud of condensation that makes it visible, and that reinforces the wonder of modern aircraft.