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1. xattt · 1790112634 · focus · HN ↗

   I am curious if anyone else can tell whether it is a high UV day just by looking outside.

   There is a certain look to the sky (slightly whiter-bluer) looking against the clouds, and I am not sure if it is because I am directly seeing UV, whether there is some fluorescence, or whether it’s placebo effect.

   1. dlcarrier · 1790143859 · focus · HN ↗

      What your describing sounds a lot like the effect of humidity in the atmosphere. You can't see the humidity itself, but it affects how a smaller percentage of light is scattered, and that you can see, to the point that, when looking out from a high vantage point like a mountain or airplane, on clear dry days you can see further than on clear humid days.

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