Does the color in infrared always correspond to temperature? Like, more so than it does in the visible spectrum?
In: Physics
Everything that’s not at absolute zero emits some thermal radiation. The exact spectrum of radiation is governed by the temperature. The jiggling of the atoms relative to each other literally does this! In simple terms the charge of different parts of atoms oscillates as the atoms move about which produces oscillating electric and magnetic fields – I.e electromagnetic radiation. Technically everything emits all frequencies, but the amount emitted becomes vanishingly small at most frequencies.
Very hot things (the sun) emit thermal radiation from microwaves, to infrared, through visible light and into the higher frequency ranges too (UV).
Things in the human living range emit practically zero visible light, but perfectly reasonable amounts of infrared radiation. This makes infrared useful in determining the temperature of “cooler” things.
There isn’t any real difference between visible light and infrared, it’s a continuous thing. Logically evolution has made our eyes most sensitive to light that’s smack bang in the middle of the spectral peak from the sun. It takes an object of several hundred degrees to glow visibly, so there are plenty of hot things that don’t glow visibly that we think of as hot.
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