The Greenhouse Effect Explained

The greenhouse effect can be thought of a little bit like the blanket you cover yourself with at night to keep warm. Our planet has an atmosphere around it containing certain gases that trap heat energy helping to keep the planet warm. And, no matter what anyone tells you, the greenhouse effect is a very good thing. No scientist would ever challenge that statement. The greenhouse effect is an entirely natural process. It was taking place long before the first lump of coal was ever burnt or the first cow let one rip.

But what exactly is it and how does it work?

The explanation starts with energy waves, presented here on the electromagnetic spectrum. Radio waves, light, x-rays… they’re all basically the same thing. We often think of them as travelling in waves and the thing that makes them different from each other is the length of that wave. To understand the greenhouse effect we’re interested in infrared waves, a fancy term for heat waves, as well as visible light. Notice that infrared waves have a longer wavelength than light waves. That’s an important detail.

As you probably know, we get our energy from the Sun. The energy from the Sun reaching our planet is mostly in the form of light energy. We’ll call this shortwave radiation to keep things simple.

Some of that energy is absorbed by the planet’s surface, causing an increase in temperature. Energy that has been absorbed and warmed an object can be then be released, but it isn’t released as light energy. The energy is released, or re-emitted, to use the correct term, as infrared waves (heat, in other words). Remember that these heat waves have a longer wavelength than the light waves that first reached the surface. From here on in we’ll call these infrared waves long wave radiation.

Next, let’s look space. Space is cold. Its baseline temperature is about -270 degrees Celsius. Very cold indeed. Far too cold for life to exist. Fortunately, since our planet orbits close to the Sun (close in astronomical terms, that is) we are kept well above that temperature.

However, if the Earth were to absorb and re-emit energy the way I’ve already described, and all of that long wave radiation is allowed to leave the Earth system, the average temperature of the surface would be around -18 degrees Celcius. That’s better than the -270 of space, but still fairly cold. We know the Earth isn’t really that cold… so what are we missing? Enter the greenhouse effect.

Fortunately for us, specific gases in our atmosphere, gases such as carbon dioxide, methane and others, all known as greenhouse gases, are able to absorb and re-emit the long wave radiation coming from the surface of the Earth. Now remember, shortwave radiation reaches us from the Sun, but long wave radiation is radiated from the surface. These greenhouse gases are not able absorb short wave radiation reaching the Earth. Consequently, they let the Sun’s energy in, but then trap some of it as it tries to leave. This trapping of heat energy obviously raises the temperature in the atmosphere, Earth’s surface and it’s oceans.

So basically, our atmosphere traps some of the heat energy in the Earth system, keeping it that bit more warm. As a result of Earth’s natural greenhouse effect the average temperature on our planet is about 15 degrees Celsius, 33 degrees warmer than it would be without any greenhouse effect.

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[framora]

I'm a college student and my professor didn't explain it like this but now I understand it very well! Thank you!

[zzubra]

I am a physicist who spends a lot of time in conversation with folks who deny the reality of the greenhouse effect. This video offers a competent recitation of the most common ways of explaining the greenhouse effect. Unfortunately, that means that the video does little to clear up the most widespread misunderstandings of the greenhouse effect. So, the video may be useful to those sympathetic to science and who don’t require a deep understanding, but it won’t be helpful to anyone who is suspicious of science and scientists. / One thing I wish the video had said is that, concretely, the “greenhouse effect” is the 40% reduction of the amount of longwave radiation that reaches space relative to the amount of longwave radiation emitted by Earth’s surface. This is something that is measured; it’s not simply hypothetical. And, the measurements are well-matched to theoretical predictions. / Saying heat is “trapped” frequently stimulates misunderstandings, with people thinking it means heat is literally stuck inside CO2 molecules and can’t leave, or stuck at Earth’s surface and can’t leave. Yet, what it actually means is that, for a given surface temperature, the rate at which heat escapes to space is reduced by the presence of greenhouse gases. It’s like constricting the flow of water in a pipe, not like completely blocking the pipe. It’s comparable to increasing the “R-value” of insulation in a home. / I also wish explanations wouldn’t focus on “re-emission” of radiation back towards the surface (something thankfully only hinted at in the video); this mostly generates misunderstandings. First of all, what is of primary importance is that radiation doesn’t reach space. What is directed towards the surface is of secondary importance and is misunderstood nearly 100% of the time by those who don’t understand the detailed workings of “radiation heat transfer.” Secondly, the word “re-emission” is a misnomer. It suggests that there is a relationship between absorption and emission, when no such relationship exists. Greenhouse gases both absorb and emit longwave radiation, but these processes are independent of one another. How much radiation is emitted is a function of air temperature alone, and has almost nothing to do with how much radiation got absorbed. (Most of the heat emitted by greenhouse gasses was actual delivered to the air via convection and condensation of water vapor. On average, greenhouse gases emit more radiation than they absorb — which means that greenhouse gases have a direct effect of cooling the air; the warming effect is an emergent effect that exists on a system level, which is, unfortunately, hard for most people to wrap their heads around. The key is that, as with insulation, heat leaves the system as a whole at a lower rate than it would otherwise.)

[jojoibe]

Thank you verry much. This is the best explenation I found on Youtube! It helped me a lot for preparing my exams.

[PriyankashreeSudhakar-vn]

One of the best vedio about green house effect

[moskitoh]

One correction: Neither the amount of CO2 nor the temperature was ever stable in earth history but was always changing.

[Sir]

You make understand in Only first 4 minutes.
God bless u❤

[markasp]

People are confused because there is no greenhouse gas effect, GHGE. There are models based on misusing equations in physics.

The basic fraud of the GHGE says CO2 absorbs infrared radiation emitted when earth cools, so traps heat in the atmosphere which then warms the surface.

Q: What's wrong with that?

A: There are 3 ways in which heat is transported: convection, conduction and radiation. Surface cooling of earth is predominantly done by convection and conduction. Alarmists and modellers exaggerate the amount of radiation emitted at the surface about 250 times over. So they made it all about radiation - when - in reality - it's nearly all about conduction and convection. At much higher altitudes, when the atmosphere is much thinner radiation will become significant but for the troposphere conduction and convection are way more important.

[Mokshahlla]

probably the best video i have watched today

[Popeye]

It is very curious that there is no mention of water vapor, which makes up as much as 95% of the atmospheric greenhouse gasses. This leaves only 5% or so remaining greenhouse gas, and Humans only contribute roughly 5% of that, the balance coming from natural sources.
Tell the whole truth.

[VideoRehash]

Ngl I think I keep rewatching these so I can keep hearing that cool reggae dub jam, I'm a big two-tone fan so thanks again for making some stuff that's right up my alley
🖖🌱🏁

[davidwood]

Upper atmosphere Will cool the air . The affected atmosphere to heating up is very small . Ask someone this winter if they feel warmer outside.

[sles]

Thanks! This was much more helpful than the 10-year-old video my professor linked for us to watch. You explained it very effectively, and it helped me write my essay on the greenhouse effect and anthropologic climate change. (Also, enjoyed your speaking voice. Very pleasant!)

[Blueberry-ihgt]

Thank you so much this helps me study single science topics.

[StrayanGamer]

Please correct me if I am wrong. The quantum of the GHE seems to be exaggerated because the black body temperature of the earth if it had no atmosphere at all according to the Stefan–Boltzmann law equation. Using that formula and the observed average albedo of the earth from satellites of 0.3 gives the temperature produces the stated values of 255K or -18F. The error here seems to be that it fails to compensate for the fact that if there were no atmosphere (as required for black body calculation), there would be no clouds. However, clouds conservatively comprise 50% or more of that albedo value of 0.3 and accordingly should be reduced to a maximum of 0.15. This would mean a conservatively more accurate determination would be 268K or -5F meaning the GHE would be closer to 20K, not 33K. In reality, it would likely be closer to the moon's albedo.

[tecogyan]

Hey there great content and very informative 👍

[fractalnomics]

Glass blocks infrared just like GHGs. Should we call it a greehouse solid?

[Prince.c]

Most educative video I have watched today....thumbs up!👍👍

[katiposcotty]

Isn't awesome how the alleged "greenhouse effect" breaks the laws of thermal dynamics 😂

[irinaratushinskaja]

You have omitted the fact that the IR radiation can escape Earth and fly to the outer space only when there is no longer enough GH gasses or aerosols or dust or clouds to keep it here. The black body radiation at higher altitudes (and lower temperatures) gets weaker the higher the heat needs to go to escape the Earth. That's why adding GH gasses will make Earth warmer even if the lower parts of the atmosphere are already saturated with, say, CO2.

[fredneecher]

How did you arrive at the -18C for the Earth without atmosphere? I always see that figure but I don't know where it came from. Also, greenhouses partly work by trapping the air which would otherwise rise into the atmosphere by convection. The same thing happens on Earth - some of the surface heat rises by convection, which is unaffected by any greenhouse gases.