I found several photos and a short video of the type (?) of barium cloud experiment the article refers to, https://earthobservatory.nasa.gov/images/90497/color

I found several photos and a short video of the type (?) of barium cloud experiment the article refers to, https://earthobservatory.nasa.gov/images/90497/colorful-clouds-glow-over-virginia https://earthobservatory.nasa.gov/images/90497/colorful-clou... ("Colorful Clouds Glow Over Virginia" (2017)) https://www.nasa.gov/solar-system/nasa-launches-two-rockets-studying-auroras/ https://www.nasa.gov/solar-system/nasa-launches-two-rockets-... ("NASA Launches Two Rockets Studying Auroras" (2019)) - "The AZURE mission is designed to make measurements of the atmospheric density and temperature with instruments on the rockets and deploying visible gas tracers, trimethyl aluminum (TMA) and a barium/strontium mixture, which ionizes when exposed to sunlight. The vapors were released over the Norwegian Sea at 71 through 150 miles altitude."