Just about the only reason I like yoyoing outside is the “glowing” effect that your string gets under natural light. I always wondered why it looked so bright compared to the surrounding area, but watching this -->
explained a lot of it.
Essentially, the light that hits the yoyo string is reflected off at different intensities with different amounts of each wavelength of light depending on the string color and light source. Some yoyo strings happen to reflect some wavelengths more strongly than others and natural light happens to have more of that wavelength.
This probably isn’t exactly what’d going on, so I wanted to throw this up to see what kind of ideas other people have
Example of the effect -->
Circle City Muse w/ Kitty XXL in Hot Pink