Schlieren flow visualization

We’ve all seen diagrams of how sound works, of how waves radiate from something that makes noise. But wouldn’t you like to be able to actually see how that sound spreads? How it ripples through the atmosphere? It turns out that you can, and it takes a centuries old technique known as Schlieren flow visualization.

As explained by NPR, this technique uses a light source, two parabolic mirrors, and then a light blocking edge to create a very specific image on a camera’s sensor. This setup shows disturbances in the air from airflow and heat—but also from sound waves. The video below explains it very well, and it’s an incredible real life look at everything from a clap to a gun being fired.

The videos themselves come from Michael Hargather, a professor of mechanical engineering at New Mexico Tech, who specializes in “the development and application of optical techniques to the study of high-speed compressible flows and explosions.”