I’m researching for a project about greenhouse gasses and I can’t find an answer on why this is. Please explain!!
In: Physics
IR radiation doesn’t emit heat. Rather, it warms up things that it hits.
The full electromagnet spectrum is as follows, from longest wavelength to shortest.
Radio, Micro, infrared, visible, uv, x-ray, gamma.
Radio waves are very long. Ones used for communication typically have wavelengths measured in feet. That’s why the long antenna, so that the full wave can be captured.
Shorter microwaves and longer infrared waves are absorbed by water very well. This is why microwaves are used to heat foods, and why infrared light can heat up your skin and convey to you that you are near something hot.
Uv waves are so small that they don’t effect things on the scale of objects, but on the scale of atoms. They produce light radiation that is described as “ionizing,” a fancy way of saying that they can break down molecules. The most important molecule to us humans is DNA, which UV can destroy, causing cell death and subsequent sunburns. However, this breakdown of molecules doesn’t really cause the object they’re a part of to heat up on a large scale, and, thus, heat isn’t felt by people.
Side-note:
There is a physical phenomena known as blackbody radiation. In simplest terms, as objects heat up, they emit light. The hotter the objects are, the more powerful the light that they emit is. You can Google pictures showing the spectra emitted by different temperatures, but, it’s how old incandescent lightbulbs work, why things glow when they get hot, and why flames exist. Usually, though, things that humans heat up produce most of their radiation in the form of IR. That’s why you can feel the heat of a strong fire from feet away. You aren’t being heated through the air, but through IR light. There are also various indoor heaters that blast a room with IR.
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