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Comment by TeMPOraL | Hacker News Reader

> The reason for this is that the sun is at a low angle, so it hits more of your body than it does when the sun is overhead - like you'd get in Australia. This also means that while you need some sunscreen during the day - from about 10 to 5 - it doesn't burn as much.

Not sure if I parse this correctly - I'd imagine you need more sunscreen at "low angles" due to more severe and longer exposure? Low angle -> more body surface area exposed directly at near-right angle to Sun -> more direct absorption -> more sunscreen needed?

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I’ve found the UV index forecasts to generally be a good metric, so try looking at those for various locations. The main factor here is that the lower the sun is from the horizon, the more its light will be absorbed by the atmosphere due to the longer path. The maximum altitude that the sun will ever reach is (90° – (latitude – 23.4°)), so at the 60°-ish of Scandinavia it’s rarely more than 50° in the sky. It’s a very noticeable difference even in the summer. In my experience (born in southern Italy, pale-average, currently living in Sweden) it’s almost impossible for me to get sunburn in daily life in Sweden even without sunscreen. Definitely not so further south.

> it’s almost impossible for me to get sunburn in daily life in Sweden even without sunscreen.

Um most Swedes, even with not-super-pale skin get a sunburn every june. Just being outside in the sunshine for 2-3 hours without any protection and they turn "kräftröd" as they say.

Swedes have an almost comical compulsion to stay in the sun. Growing up in a hot place you get the opposite instinct.

Still, it’s known that your skin color is the main thing that matters, which is why Australians have the worst melanoma statistics. I guess mine tans fast enough to keep up with the seasons here.

No, because the sun at low angles passes so much atmosphere, that filters most out.

The exposure angle of your body also has a effect, but much weaker.

Today in Stockholm the UV index peaked at 6.3. And it is just a few days after the summer solstice, and the sky was largely clear today.

(Yet I can feel that I got slight sunburn being out for about 15 minutes today. So you still need to be careful.)

In winter the UV index might often peak at 1-2 on a clear day.

at lower angles the sun light needs to go through a much bigger "cross section" of atmosphere which greatly reduces its energy.

This is why noon sun is the most dangerous.

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