If infrared light is a type of radiation emmited by atmospheric molecules how is it that the human body ‘glows’ so much more than its surroundings?
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Black body radiation
All matter that has temperature (ie not at absolute zero) will emit light. Humans are cool enough that we don’t emit visible light, but we do emit infrared light.
When you heat something up red hot, that just means it’s hot enough that it can emit red light. When something is white hot, it’s hot enough to emit all colors of visible light.
We can tell how hot the surface of distant stars are by just looking at what colors of light it gives off. Red is the coolest, then yellow, then white, then blue being the hottest. We also consider infrared, UV, and x-rays when measuring the temperature.
The IR thermometers you may have become familiar with during covid use this fact to measure the temperature of humans quickly and efficiently. It just compares the intestity of different infrared frequencies so we can quickly differentiate between a human at 98°F and one at 100°F. It’s not as accurate as an oral thermometer, but it’s faster and cleaner.
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