EXPLAINED: Global Warming

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..

The Air On Mars Has A Mysterious Glow. Here’s Why

With a rarified (or super thin) atmosphere looking at the stars from Mars must be incredible! But at night on Mars, there's also another source of light … the atmosphere of the Red Planet is literally glowing! Howdy glow worms, this is DNews, and I'm Trace. Nightglow is the tendency for the atmosphere of a planet to glow in complete absence of external light. This bizarre effect was spotted in mid-2016 by MAVEN. The Mars Atmosphere and Volatile EvolutioN mission was sent to orbit Mars to ascertain how Mars was stripped of its ancient atmosphere. But, while analyzing ultraviolet pictures scientists spotted this nightglow in the swirling high-altitude air of our rust-colored neighbor… Okay first, MAVEN has found that the sun's constant barrage of energy from it's nuclear reactions have slowly stripped the atmosphere of the planet to it's current level, 100 to 150 times thinner than our on Earth.

That same stripping of the atmosphere is causing the nightglow that MAVEN spotted! When ultraviolet light from the sun hits the "leading edge" of the planet the energy in the particles break down carbon dioxide, nitrogen and oxygen which are all floating around in the Martian sky. This is called photodissociation. The now-broken-up particles, are then carried on high altitude winds all around the planet. Once they reach the nightside of Mars (away from UV light), those free nitrogen and oxygen atoms interact — combining to form nitric oxide between 60 and 100 kilometers above the dusty surface [. When they do that, they release energy, causing this nightglow! It's basically the same idea used for glow-in-the-dark toys or glowsticks! Scientists are excited because it's very difficult to map the movement of the Martian atmosphere! Taking "pictures" of this glow can help scientists determine what's happening down there throughout the Mars year.

They can see how air moves in different Mars seasons, better understand the planet's cloud formations, and thanks to ozone formation, find water molecules. To be honest, nightglow is completely normal, and Mars isn't the only planet that has it… it's been seen on Venus, and a little planet you may have heard of, Eeeahhrth?! Just like on Mars, Earth's nightglow is caused by chemical reactions in the upper atmosphere, between 85 and 95 kilometers up. And just like on Mars this glow is very faint; NASA's Earth Observatory says the glow on our planet is about a billionth as bright as sunlight. So, it's very hard to see, but it's not invisible. A 2005 study in Astroparticle Physics found about 564 photons per meter squared, per second, over the Mediterranean Sea. And, if you were on the International Space Station looking sideways at the atmosphere you can see a faint glow… that's Earth's nightglow! We know a bit more about our own nightglow — for example, just like on Mars, the solar wind photo dissociates molecules in our upper atmosphere, and when they recombine they release energy as green, blue, yellow, and red light: oxygen glows green or blue, sodium yellowish, and hydroxls, or OH molecules glow red.

Science is beautiful, ain't it? Nightglow is just another byproduct of the sun's neverending assault on our atmosphere, and the atmosphere of other planets in our solar system. What a warm nuclear ball of awesome. Worried that the constant barrage of solar energy is actually going to steal our atmosphere? Can we run out of oxygen!? Check out this video with my girl Julia for more on that. And what is your favorite science topic? Space? Environment? Animals? Physics?! Tell us in the comments. Thanks for watching! Please subscribe so you get more DNews..