• proctonaut@lemmy.world
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    22 days ago

    Is there any way to tell the difference between infrared reflected between (I assume) 8 and 13 microns and the infrared emitted due to absorption of shorter wavelengths?

  • stoy@lemmy.zip
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    22 days ago

    Just get some loose linnen button down shirts, they are fantastic

  • Thorny_Insight@lemm.ee
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    22 days ago

    That’s not exactly heat absorbtion though. Infrared cameras capture the heat radiated by the shirts and black color is the one that radiates heat the best. That’s why matt black is the worst color for a thermos and chrome is the best.

    • Umbrias@beehaw.org
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      21 days ago

      If they have identical or close enough emissivity it is directly proportional to heat absorption, as given identical amounts of time in the sun and air flow, temperature will almost entirely depend in absorptivity, and emitted infrared is proportional to temperature^4.

      Black bodies emit and absorb perfectly. These probably all have an emissivity that’s lower than a blackbody, and very close together, while absorptivity is related to the color of the shirt. So this test is actually fairly indicative.

  • spicy pancake@lemmy.zip
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    20 days ago

    my friends make fun of me for wearing black in the summertime but i am more uncomfortable wearing non-black than i am just sweating it out 🫠

  • Etterra@lemmy.world
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    22 days ago

    Also a good indicator of why must plants use chlorophyll, which primarily reflect green light in our planet’s biosphere.

  • Donkter@lemmy.world
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    22 days ago

    So does black make a significant difference when it’s colder? Or is it only noticable when there’s harsh sun?

    • BCsven@lemmy.ca
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      21 days ago

      Google says : colors do not absorb different amounts of heat, only heat from light.

      • antlion@lemmy.dbzer0.com
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        21 days ago

        Body emits infrared radiation. Sun does too. They make foil-lined jackets to reflect this heat. White shirts do it too, as shown in the image.

        • BCsven@lemmy.ca
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          20 days ago

          Not according to science articles on the web. infrared penetrates regardless of colour, visible light spectrum capturea or reflects the rest.

          • Umbrias@beehaw.org
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            20 days ago

            It depends on the absorptivity of the pigment at that given wavelength. Foil for example works because in ye infrared it is still reflective. Without an infrared camera and an infrared light it’s impossible to tell what the infrared absorptivity of a given shirt is by eye. The science articles are not giving the full picture.

            • antlion@lemmy.dbzer0.com
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              20 days ago

              It seems it’s still an active debate and area of research, but the answer is more complex than wavelengths and emissivity. If you want to know whether black or white is cooler in the sun, it depends on: the breathability or knit, the amount of UV hitting the skin, the amount of skin contact with the fabric, wind speed, relative humidity, how the fabric wets and wicks moisture, and more. We could look at a black trash bag and say, well it’s transparent to IR, and it blocks the visible spectrum, therefore it’s a good shirt material to keep one cool. And obviously that would be wrong. In the same way it’s wrong to say: a white shirt feels less hot when you touch it, therefore it keeps the wearer cooler.

              • Umbrias@beehaw.org
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                19 days ago

                Yes, all of that is obviously true between shirts, the question is about shirt color, which is almost entirely down to the pigments used in fabrication. In which case it is entirely due to the absorptivity, emissivity, reflectance, and opacity, of the pigment.

                This isn’t an active area of debate, it’s an entirely empirical question or a hard modeling problem per shirt manufacturer. All of this is very solved science, and has become “an engineering problem”

    • Shawdow194@kbin.run
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      22 days ago

      I guess gray is just black and white mixed, and black does not do very well

      Yellow also reflects a tonne of UV and IR light. Probably helps make it so much more visible to everything than other colors

      • Wahots@pawb.social
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        21 days ago

        Do you use aluminum/antiperspirants? I think that is what causes the staining.

        • spicy pancake@lemmy.zip
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          20 days ago

          yup, the aluminum basically acts as a mordant for the natural yellowish stain of sweat and its microbial metabolites

          best to skip antiperspirant when wearing white shirts. aluminum-free deodorant (there is no such thing as aluminum free antiperspirant, btw) can help mask BO but will not stop sweat. but if you like white shirts that’s probably a decent trade-off.

          zinc oxide is a decent deodorant ingredient that doesn’t prevent sweating but does slow down microbes that eat sweat and release odorous compounds

          avoid baking soda if you have sensitive skin as it can raise your skin pH to uncomfortable levels. ymmv

    • intensely_human@lemm.ee
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      21 days ago

      Well a dog. Could guess it I mean.

      If dogs can guess things, which I don’t even know if they can. But maybe.

      I think maybe a dog could guess it.

  • Blackout@kbin.run
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    22 days ago

    What about sequined shirts? If I get the right angle I can boil a cup of water within seconds while staying cool inside. For an extra barrier I wrap my body in foil, keeps the 5g out as a bonus.