Hot answers tagged protection
11
Around sunrise and sunset, the sun is much less intense. You would get around 5 times less intensity in the first or last hour of sunlight than in the middle of the day. Here is a graph of this effect (It's from a paper, though the paper itself is behind a paywall), and another one which also shows the effect of latitude.
Therefore, while you can’t say ...
7
As found here:
"With every 1000 m in altitude, UV levels increase by approximately 10 per cent."
Percentages are tricky to work with, so here is a worked-out example. Suppose you start out at sea level (0m), and you climb all the way up to Mt. Everest's summit (8848m). Suppose also that at sealevel, you normally need to apply sun block factor 15. Then, ...
5
Heat illnesses are about heat, not light, and while the two are not unrelated, the hue of your clothing would be a very minor factor— red would not provide better or worse protection than green or blue or any other part of the visible spectrum.
The shade may have some impact: since darker clothing absorbs more energy than lighter clothing, it warms up and ...
2
A white colour for head protection (and all other clothes) will keep you the coolest, black will keep you the hottest. All other colours are somewhere in between.
This is because white fabric reflects the most light (all wavelengths of visible light), while black absorbs all (red reflects only the red channel).
As for the efficiency - I have sometimes ...
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