• mindbleach
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    11 days ago

    to which the atmosphere is unsurprisingly transparent.

    The sky is blue specifically because that’s wrong.

    • bane_killgrind@slrpnk.net
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      9 days ago

      so it’s blue because specifically that wavelength of light is scattered, not the rest of it. it’s not reflection, it’s refraction.

      • mindbleach
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        9 days ago

        You are within sight of a blue LED. Does that monochromatic blue look like the blue of the sky? No. Because Rayleigh scattering diffuses higher wavelengths more, not exclusively.

        Even a deep red sunset scatters enough light to overwhelm the stars.

        Cooling paint emits light deep enough in the infrared that this effect becomes negligible. It proportional to frequency, to the fourth power.

        • bane_killgrind@slrpnk.net
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          9 days ago

          The sky is not emitting light, it is refracting light, like a prism. A blue LED is emitting light at different wavelengths than the blue of the sky.

          • mindbleach
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            9 days ago

            … no shit.

            Like a prism, it affects all wavelengths. If it was “specifically that wavelength,” “not the rest of it,” it would be monochromatic. Like an LED. But it’s not. Rayleigh scattering diffuses any near-visible photons, at a rate proportional to their frequency, squared, squared.

            That’s why cooling paint works differently than merely reflecting light. Even red light can scatter in the air and warm up the environment. Red scatters less than blue… but infrared scatters less than anything visible.