Re: Why is hi-vis clothing easier to see? What ?s so special about the colour?

Actually in the early evening after sunset the scattered light from the blue sky is very UV rich as a proportion of the fading twilight. You can often see things fluorescing an hour or two after sunset at this time of year. If you are lucky you can also see faint electric blue notilucent clouds that are so high they remain in sunlight long after sunset.

The typical fluorescent dyes and pigments will convert blue and shorter wavelength photons into yellow, orange or red emitted light. The same fluorescent dyes are used in the cyalume cold chemical lights.

The reason day-glo materials look so bright is that they emit more light of their selected colour than is present in the incident sunlight.

It is the ratio of diffuse UV and blue light scattered from a clear sky to the low light level of dusk. In direct sunlight there is a lot more UV but there is much more visible light too. When the sun goes down the mid band visible light decreases fastest leaving some reds and UV.

The intensity is well down but the proportion of UV is much higher.

OH daer

Stupid is as stupid does.

Florescence means flowering.

This reminds me of, "If English made any sense, lackadaisical would be to do with a shortage of flowers".