False-color shadowgram of gunshot from a .357 magnum by Gary Settles at Penn State university.

The New York Times has an awesome slideshow of shadowgrams and Schlieren photographs, created by engineering professor Gary Settles, which accompany a 2008 article about his work at Penn State’s Gas Dynamics Lab. The method, which can produce fantastic visualizations of fluid flow in turbulent systems, is amazingly simple. I am surprised there aren’t more hobbyists doing it.