There is a digital UV-wavelength video of the corona, and a visible-wavelength video of the trees.
The paper [1] contains a sole picture with tiny circles indicating where the UV-video detected corona events, overlaid over a frame of the visible-wavelength video.
The paper does also contain a video [2] which overlays a somewhat processed version of the UV video over the visible wavelength video, where UV photon events are indicated by decaying red dots.
[1] https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2025GL11...
[2] https://agupubs.onlinelibrary.wiley.com/action/downloadSuppl...
If you come to my day job, and we shut off all the lights in the test room, after your eyes adjust in the dark for a minute, you'll see the soft purple glow coming from the edge our 160kV test rig.
Definitely emits UV, but there is enough visible to see it for sure. It comes from the electrons exciting nitrogen in the air.[1]
1. https://commons.wikimedia.org/wiki/File:Nitrogen_discharge_t...
At least personally I scanned the article for it and only found the picture at the top, which I was then frustrated to learn that's just a lab photo, and I came here wondering where the actual image is of it in the field so I found OPs comment helpful to indicate that the suggestion there would be a beautiful picture of glowing canopy somewhere is basically a result of editorializing.
Coincidence? Probably.
Very cool phenomenon to catch visually.
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022JD03...
> Visually, the corona discharges generated on the leaves were either small purple-blue point discharges or elongated purple-blue discharges, and usually formed on the tips of the leaf closest to the source of the electric field (Figure 1). Sometimes the corona discharges were steady and constant, but other times they would dim and brighten in an unsteady pulse. When the corona was turned off, the tips of the leaf where the discharges occurred were often burned and browned, even for the weakest electric fields applied to the leaves.