Howdy. It’s me again. It’s been a while. Um, I haven’t made a video in quite a while because reasons. So I’d like to reintroduce myself, but won’t because we have some science to talk about. Follow me. We’re not going anywhere, so just stay put. If you’ve ever listened in on a conversation about global warming, you’ve probably heard that it’s a greenhouse effect caused by carbon dioxide in the earth’s atmosphere trapping in the heat from the sun. While this simple one sentence explanation is indeed correct, is brings up another question that I don’t hear asked very often: “If the earth is able to use the layer of carbon dioxide in the atmosphere to trap in heat from the sun, why does that same layer of carbon dioxide also not block the heat from ever getting into the atmosphere to begin with.
” People often describe this greenhouse effect as if the carbon dioxide is acting as a two-way mirror, which allow the sun’s rays to pass through the atmosphere when they’re coming in from space, but then traps them in after they’ve been reflected back off of the earth’s surface. It doesn’t make any sense. So what’s the deal? Are carbon dioxide molecules special or something? Do they have, like, a shiny side that’s always faced down that’s constantly reflecting the heat off of the earth? Yep! No… no they don’t. You’re dumb. But I’m you. Oh right. So we all know that the sun emits visible light, and most of us have heard ofthose nasty UV rays that cause sun burns and turn normal people into reality TV stars.
So in order to answer the question of how global warming is even possible, we’re going to have to talk about radiation. Electromagnetic radiation. So… light… just light. Ultraviolet light is a high frequency electromagnetic radiation that’s invisible to the human eye and is what’s responsible for heating up the surface of the earth. However, it does not heat the air. UV light comes from the sun, and because of its short wavelength, is able to pass through the carbon dioxide in the atmosphere, and is gets absorbed by the earth’s surface… or your skin… if you’re lucky. But not all of that UV light can get absorbed by the ground. The leftover energy gets reflected back away from the earth’s surface, but at a lower frequency we call infrared. Infrared light is a low frequency electromagnetic radiation that we also can’t see with the human eye. But even though we can’t see it, we can feel it… and we call it heat. It’s this infrared radiation that warms the air, and because if it’s longer wavelength, the carbon dioxide is able to trap it in and keep it close to home. Here’s a quick visual to put all the pieces together and help make sense of things.
The sun produces UV light which passes through the carbon dioxide in our atmosphere. The earth’s surface absorbs most of the UV light and heats up. The leftover energy is reflected away from the earth as infrared radiation. The infrared radiation heats the air and is trapped in by the carbon dioxide. So there you have it. Hopefully that made sense and you learned a little something today. Thanks for watching. Have a good one. Oh, one other thing. Nothing, I just wanted to do that split screen thing again. Dude, get the **** out of here! Ok, sorry..