Thread

1. nomel · 1790116546 · focus · HN ↗

   I don't know about this. I can feel where there are holes in my sunblock (which only block UV) which lets me know where to apply it, and the sensation is not one of heat of the sun, it's different. I'm not sure about the mechanism, but the presence of the sunblock stops the "UV" type sensation. This from the moment I put it on to long after the water component of the sunblock has evaporated. And, the type of sunblock doesn't matter (the drier waterproof kind or various lotion varieties). And, I do notice a difference between the different SPF, along with some "bad" sunblock that I just kept applying but couldn't make the feeling go away (it had apparently separated, and everyone that used it was burned).

   I think the "real" test would be to just shine a UV light in a dark room, to see if the source can be identified while blindfolded, or something.

   1. taneq · 1790124432 · focus · HN ↗

      I’ve always thought of sunblock as taking the ‘sting’ out of the sunlight. It’s a separate sensation that I can feel even on a cold day.

      This is in Australia where the hole in the ozone layer often results in 10x ‘normal’ UV levels, you can get noticeably burned in a few minutes.

      1. jandrewrogers · 1790128796 · focus · HN ↗

         Australia’s UV is only modestly higher than other places at similar latitude. It is similar to equatorial regions and isn’t remotely close to 10x anywhere. You can experience the same UV index in the tropics.

         Some parts of South America have a UV index twice that of Sydney’s maximum. All of the actually extreme UV index locales are extreme altitude and near equatorial.

         1. piltdownman · 1790167857 · focus · HN ↗

            The Peruvian Andes has the most extreme UV index in the world due to being 10,000ft+ above sea level and on the most susceptible line of latitude. That being said, even with the atmospheric deficit, the max peak recorded by ground and local meteorological observations was 18. Can't seem to find a citation for 2x Sydneys max (14/15).

            Indeed looking at Oceania; Sydney, Perth, and Auckland all hit 14/15 regularly in the Summer months. Auckland in particular has ~40% more UV than comparable northern latitudes.

            Given the genetics and immigration is heavily skewed in favour of the British and Irish diaspora, it's about 3x the UV Index of what the UK and Ireland see. Dunno where 10x came from.

            1. jandrewrogers · 1790179744 · focus · HN ↗

               The UV index is >20 in the Andes of the northern Atacama. It is considerably stronger than the tropics thanks to the extreme elevation and ~0% humidity. The global record for UV is at Licancabur on the Chile/Bolivia border with an index of 26-43 (the exact numbers are apparently contested). We only know this because scientists study the unusual lake there. Some other places in the region that few people visit are almost certainly higher based on their geography.

               The highest UV index I can find for Sydney is 14, which is typical of many places in the tropics.

               I've spent time in the 20+ UV of the northern Atacama and it is a different beast. The indirect UV reflected by the soil is strong enough to burn you even if you are not exposed to direct sun. It requires precautions that I never needed in Australia or elsewhere in the tropics.

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