2011-01-18 14:44:38My first Post: TFK09 - Unpacking the Greenhouse Effect. Draft, Comments Please
Glenn Tamblyn

glenn@thefoodgallery.com...
124.180.32.44

In for a penny, in for a pound. I have made some of comments here at the forum, time to contribute something more substantial. The following is a draft of a post I am working on, looking at what Trenberth Fasullo & Kiehl 09 can tell us about the greenhouse effect. Comments please. Particularly general thrust of the piece, is it too long, to wordy, not graphic enough. Any obvious bloopers? Also I am looking for a good graphic of the Earth’s OLR spectrum. I have seen them here before but damned if I can find it.

http://www.skepticalscience.com/GT_TFK09_UTGHE.html
2011-01-18 15:03:25Quick first comment
John Cook

john@skepticalscience...
121.222.100.112

Glenn, thanks for writing this. I haven't read it in detail yet but first quick comments:

Can I suggest a more intuitive filename like Unpacking-the-Greenhouse-Effect so that the URL would be:

http://www.skepticalscience.com/Unpacking-the-Greenhouse-Effect.html

That looks a lot more intuitive (and attractive) when people link to your blog post from other websites, forums, discussion threads, etc.

Second, is this the OLR spectrum graphic you're after? Taken from Greenhouse effect has been falsified:

IR spectrum at  the North Pole
Figure 1. Coincident measurements of the infrared emission spectrum of the cloudfree atmosphere at (a) 20km looking downward over the Arctic ice sheet and (b) at the surface looking upwards. (Data courtesy of David Tobin, Space Science and Engineering Center, University of Wisconsin-Madison. Diagram courtesy of Grant Petty, from Petty 2006).

If you want this graphic as is, just copy and paste it from here into your blog post. If you want an edited version with just the top half, let me know and I'll upload an amended graphic.

2011-01-18 15:25:57Ta
Glenn Tamblyn

glenn@thefoodgallery.com...
124.180.32.44

Thats the one. Thanks John

 

Updated. Here is the new name http://www.skepticalscience.com/TFK09_Unpacking_the_Greenhouse_Effect.html

2011-01-18 18:12:50
Rob Painting
Rob
paintingskeri@vodafone.co...
118.92.71.175
One heck of a long post, but an enjoyable & informative read nonetheless. Is this going to be the advanced version of the Greenhouse Effect has been falsified?. 
2011-01-18 18:20:30
Glenn Tamblyn

glenn@thefoodgallery.com...
124.181.218.213

Rob

We all have many strengths & weaknesses in life and modesty precludes me from listing all my many virtues but, sometimes, brevity isn't one of them. Any suggestions on how to abreviate it.

I'm currently working on the advanced version of the Troposphere isn't warming rebuttal.

G

2011-01-19 01:52:25
MarkR
Mark Richardson
m.t.richardson2@gmail...
192.171.166.144

I did a small course that included being brutal with words and cutting, so I'm confident you can do it! I usually find I can take out 20-50% of my wordcount without ruining the point...

 

Some technical points: metres should be a small 'm' always.Quite often you are talking about what is technically a 'power flux' and you use the word 'energy'. Everything you give that is in units of W m-2 is a power flux. The term 'heating' is usually vague enough to get by with; whilst energy/power have more specific meanings! (this is pretty anal, but it doesn't hurt to be right and any skeptics might just think 'ha, he doesn't know the difference! Must be rubbish...')

 

 

html editing: And Watts/M^2 is more easily written W m-2 where you superscript using the < s u p > - 2 < / s u p > script (remove spaces :p )

 Kelvin does not usually have a degree symbol before it, it's usually just 'K'. For degree symbol ° use the html & d e g ; having deleted the spaces.

 

 I'd suggest culling lots of the words and adding titles to break it up into sections. My edits are below, cutting the first 1010 words down to 623. If you could knock 40% off the overall length you should get a lot more reads!

Let me know if you think my editing style fits with what you want to say. If so, I could try culling my way through the rest.

 

 

 These are my edits up to the line just before you introduce the Stefan-Boltzmann equation.

"What data is available for us to use to look at the Greenhouse Effect in action? To ‘unpack’ how it works?


The paper Trenberth et al 09 (‘TFK09’) is a synopsis of a range of works (such as ‘KT97’ Kiehl et al 1997) to produce an ‘Energy Budget’ for the Earth. They want to measure the key energy flows within the Earth’s climate system to find out where the energy comes from and where it goes. I’m going to ‘unpack’ the energy flows they identified to explore the Greenhouse Effect and discover that Earth would be a snowball without them.

Using the data from TFK09 we can do some rough ‘back-of-the-envelope’ (BOTE) calculations to try and highlight the role played by greenhouse gases. TFK09 give a nice picture so without further ado, The Graphic:

The size of the arrows shows the size of the energy flow, not the storage. It’s like measuring the water flowing into the bathtub from the tap and out through the plughole, but not the total amount of water in the bath. They are also only dealing with flows between the Sun, Space, Earth’s Surface and the Atmosphere, but not inside the oceans or in melting ice etc.

Thirdly, this is a snapshot of one fairly short period and the graphic is an estimate of the flows with associated errors and isn’t accurate to the nth decimal point. The errors aren’t in the graphic, but they are in the original work TFK09 use.

Finally, these are global averages so won’t be accurate at any single point on Earth – there will be more evaporation over warm oceans for example.

What do we see? Incoming Solar Radiation (Ultra-Violet, Visible and Near Infra-Red) is 341 Watts/M^2 (from now on, every time I give a figure the units will be W m-2). This is the average heating from the Sun, divided by 4 because the Earth is round but only gets sunlight from one side. 102 in total is reflected and is like a ghost – it passes through but doesn’t do anything. 78 is absorbed by the atmosphere and 161 by the surface.

Then the surface loses energy: 17 rises up into the atmosphere via the thermal updrafts that lift gliders and condors whilst 80 is carried aloft by the evaporation of water at the surface and its condensation higher up.

Next is Surface Radiation at 396. This is Long Wave (or Far Infra-Red) Radiation from Earth’s surface directed upwards. About 40 of it makes it straight out to Space through the ‘Atmospheric Window’ – the range of frequencies where the atmosphere does not impede the radiation. 356 does not make it directly to Space! 90% of the radiation from the surface is recycled in the atmosphere.

This warms the atmosphere, which sends 333 back down to the surface as Back-Radiation (or ‘Down-Welling Long Wave Radiation’) and 199 out to space.

This is a complex picture and I had to look at it lots of times: what does it tell us?

Firstly, the Earth is in rough energy balance. 341 IN roughly equals (40 + 169 + 30 + 23 + 79) OUT.

Next, there is more energy coming back down to the Earth’s surface from the Atmosphere than is coming from the Sun. Um, what? Solar energy flows into the Earth and ultimately flows out to Space again. While it is here however, nothing prevents this energy from being ‘recycled’ before escaping. There is no reason why this ‘recycling’ flow within the system can’t be larger than the flows going through the system.

Also; why does the atmosphere send 333 down but only 199 up? Is a molecule in the atmosphere more likely to radiate down rather than up? More on this later…"

2011-01-19 02:07:10
MarkR
Mark Richardson
m.t.richardson2@gmail...
192.171.166.144

More physics:

Your first step where you 'fudge' the emissivity isn't very well explained. The reflected light has nothing to do with the equation! You are ONLY interested in the outgoing flux total, the reflected component is irrelevant - it's like a ghost!

The emissivity of the Earth's surface is comfortably above 0.9 iirc. It's usually approximated to 1. Sand, water, snow etc emissivities at some wavelengths here.

 

If you use the 0.95 or whatever surface emissivity you do overestimate Earth's temperature, but this probably comes from how the flux is determined from the quartic-root-mean-to-the-power-fourth temperature of all places on Earth and not the mean temperature!

 

 

A few other things need rephrasing I think, but I don't have time to read now. :)

2011-01-19 12:01:51
Glenn Tamblyn

glenn@thefoodgallery.com...
138.217.120.240

Thanks Mark I'll go to work on Vsn 2

2011-01-20 00:22:25Vsn 2
Glenn Tamblyn

glenn@thefoodgallery.com...
60.230.14.127

New version here 

Its late and I still have a few tidy up things to do & add some notes at the end.

This is somewhat shorter but should have a better structure.

Opinions!

2011-01-20 11:27:12
MarkR
Mark Richardson
m.t.richardson2@gmail...
134.225.187.80

First thing that springs to mind: perhaps do the equations in LaTeX or MS equation editor and then turn them into a picture to import in? Would make them look clearer, especially with division and the likes.

 

 

If you have the MS word 07 or later then you can access equation editor with ALT plus = at the same time, and then it accepts LaTeX math commands, such as \delta for δ

2011-01-22 00:29:37
Glenn Tamblyn

glenn@thefoodgallery.com...
121.220.24.84

Latest version here 

I'm happy with this since it says what I want it too. Any other comments? If not I will ask JC to post it in 48 hours.

2011-01-22 01:22:25Like the "jiggle Gandalf's staff" bit
Daniel Bailey
Daniel Bailey
yooper49855@hotmail...
68.188.192.170

Seems pretty good (logic is sound, but the equations are beyond me); if I can follow it, others will be able to.

 

Cosmetic fixes for improved readability:

1.  As far as readability, some sections have 1 space, others have 2 between them.  Consistency?

2.  The equations aren't very readable; could use a cleaning up

3.  The tables could use some love: change the vertical spacings to Centered, align the numerical sections to the right (justified)

 

One given result of this post:  Ken Lambert will be howling at the moon...

2011-01-22 02:12:08
MarkR
Mark Richardson
m.t.richardson2@gmail...
192.171.166.144

1) All of the equations need to be prettied up I'm afraid. They're too important not to be! One option is to zoom into the picture in Word. They're vector graphics so they still look smooth, then you can take a BIG screengrab to turn into a .jpg and scale that using the html picture scaling tags. There's probably a cleaner way but that might work.

2) Another concern is that you're not calculating the actual effect of removing clouds etc... you're actually calculating what would happen if you magically dealt with their current heat flow, which isn't exactly right. The full calculations involve using (dR/dA).(dA/dT) to find out the radiative feedback and inverting the summation to determine the temperature response.

What you're doing isn't bad, but it is unphysical and perhaps that needs explaining a bit better.

 

3) I'd cut more words! It's still over 2,800 (although much shorter than before!), I'm gonna run through ti now and will post my suggestion soon.

2011-01-22 02:18:30
MarkR
Mark Richardson
m.t.richardson2@gmail...
192.171.166.144

Also, your epsilon ( \epsilon ) is flipped for some reason! Typically we use ε and it's worth keeping to standard symbols IMO!

In equations (e.g. where you give the value of the Stefan Boltzmann constant) I think it also looks nicer to use the multiplication symbol rather than the asterix used in coding. The LaTeX for this is \times 

2011-01-22 02:53:39
MarkR
Mark Richardson
m.t.richardson2@gmail...
192.171.166.144

And my further edits up to the first step of the greenhouse effect.

 

 I found I could cut it from 1,594 to 1,048 words. If you can cut the entire thing to around 2-2.2k then IMO it would be  much better and you won't lose anything of importance!

 

"

Trenberth et al 09 (‘TFK09’) is a synopsis of other works trying to measure where energy comes from and where it goes on Earth. We are going to ‘unpack’ the flows they identified to explore the Greenhouse Effect: finding that Earth would be a snowball without it. We will do some rough ‘back-of-the-envelope’ (BOTE) calculations to investigate the effect each flow has on the Earth’s temperature using The Graphic they produced:



The Energy Budget

The size of the arrows shows the size of the energy flows, not the storage; like measuring rainfall and drainage rather than how much water is in a lake. They also only deal with flows between the Sun, Space, Earth’s Surface and the Atmosphere but not inside them.

Next, this is a snapshot for one period with associated measurement errors which aren’t in the graphic but are in the original work TFK09 use. Finally, these are global and not regional averages – there will be more evaporation over oceans for example.

What do we see? Incoming Solar Radiation is 341 W m-2 (from now on, every time I give a figure the units will be W m-2). This is the average heating from the Sun of which 102 is reflected and acts like a ghost –passing through without doing anything. 78 is absorbed by the atmosphere and 161 by the surface.

Then the surface loses energy: 17 rises up into the atmosphere via the thermal updrafts that lift gliders and condors whilst 80 is carried aloft by the evaporation of water at the surface and its condensation higher up. Next is Surface Radiation at 396. This is Long Wave (or infra-red) Radiation from Earth’s surface. About 40 of it escapes straight to Space through the ‘Atmospheric Window’ – the frequencies where the atmosphere is transparent, whilst over 90% is recycled in the atmosphere.

These flows warm the atmosphere, which sends 333 back down to the surface as Back-Radiation (or ‘Down-Welling Long Wave Radiation’) and 199 out to space. This is complex and it is worth looking at it a few times: what does it tell us?


Firstly, the Earth is in rough energy balance. 341 IN roughly equals (40 + 169 + 30 + 23 + 79) OUT.

Next, there is more energy coming back down to the Earth’s surface from the Atmosphere than is coming from the Sun. Say what? Solar energy flows into the Earth and ultimately flows out to Space again but it can be ‘recycled’ before escaping. There is no reason why this ‘recycling’ within the system can’t be larger than the flows going through the system.

Also; why does the atmosphere send 333 down but only 199 up? Is a molecule in the atmosphere more likely to radiate down rather than up? More on this later…

First I need to introduce the Stefan-Boltzmann equation (SB): 

 

This describes the relationship between the temperature of a surface and the power radiated by that surface. E is the power radiated in W m-2, T its temperature in degrees Kelvin (0 °C = 273.15 K), ɜ is the emissivity of the surface and σ is the Stefan-Boltzmann constant (5.669 x10-8 W m-2/K4). If we measure the radiation power, we can calculate the temperature:


For an ideal ‘black body’ surface the emissivity is 1 but real surfaces are ‘grey’: most of Earth’s surface has an emissivity above 0.9 so for this BOTE equation, I’ll approximate .

The Surface Radiation flow of 396 gives us a T of 15.9 °C – a pretty realistic average temperature. So far so good.

It’s commonly said that the Earth would be 33 °C colder without greenhouse gases. This is calculated by seeing that 30% of the Sun’s energy is reflected and then using the equation to get -18 °C as the temperature without the greenhouse effect. The Graphic shows that this is simplistic with atmospheric absorption, different types of reflection etc so lets dig a bit deeper.

 

 

 

 

 

 

Waving Our Magic Wand

Imagine you are Gandalf or Dumbledore and can wave a magic wand to alter the physics of the Earth to ‘play games’. What can we learn? Starting with an Earth with no atmosphere at all and then adding back the characteristics of the atmosphere one by one until we have an imaginary atmosphere with all its real properties except the LW absorption by GH Gases. Finally we will add the GH gases back in and hopefully find something interesting.

I used the TFK09 numbers & adjusted their size depending on which were present or missing; at the end of the post is a technical note to explain what I did. The key number is the Surface Radiation value. It is this, via the SB Eqn, which shows us the surface temperature. For Reflected By Surface I assumed that the Earth’s surface reflects the same proportion as now. More on this later.


Step 1. Start with our imaginary Earth with NO atmosphere. Energy comes from The Sun, some gets reflected and the absorbed energy is re-emitted to Space. This gives us the following numbers:

With no atmosphere, the Earth would average 19.7 °C colder.

A GH Gas Free Atmosphere

Now let’s make some other steps:  Step 2. Add Atmosphere & Cloud Reflection (RCA). Step 3. Add Thermals (TH) & Evapo-Transpiration (ET). Step 4. Add SW Absorption by the Atmosphere(SABA). For steps 3 & 4 we will show two sets of numbers for each - adding back all of TH & ET, and adding back only 25% of this (to see what would happen if there was less HT/ET when it’s colder).  So, let’s jiggle Gandalf’s staff, and…

 

Step 2. reflects heat back to Space before it reaches the surface and cools things down and now we are at 36.9 °C colder, lower than the 33 °C from the example we looked at earlier. This is because this assumed that reflection from clouds and atmosphere is the same amount as TFK09 while the surface reflects the same percentage as TFK09. We will see how this pans out later.

Step 3. Adding the convective processes - TH & ET - lowers temperatures again to 51.9 °C colder because they are moving heat away from the surface to the atmosphere which re-radiates this energy in an assumed 50:50 up:down split (more on this later...)"

2011-01-22 02:55:39
MarkR
Mark Richardson
m.t.richardson2@gmail...
192.171.166.144

Your first observation of the greenhouse effect isn't that clear IMO. It sounds like you're saying that thermals and latent heat transfer will lead to the greenhouse effect causing more warming, which it clearly doesn't.

 

They are a net cooling effect (because they reduce the total upgoing infrared which could be intercepted by greenhouse gases anyway), but atmospheric warming=more back radiation is a good point. I just think it's not too clear atm.

2011-01-22 08:19:50
Glenn Tamblyn

glenn@thefoodgallery.com...
124.180.144.120

Thanks guys

One thing I have struggled with is getting the spacing between para's consistent. Editing in Author Admin is giving me inconsistent results. Any tips?

2011-01-22 08:33:15Editing
Daniel Bailey
Daniel Bailey
yooper49855@hotmail...
130.36.62.222

I have the same frustrations on the editing.  I'm sure John edits just fine in the HTML window, but many of the tags are unknown to me there.

I just exercise caution, save my work often, use the delete key instead of the backspace key and exit without saving if I screw up unrecoverably.

Works, somewhat, for me.

2011-01-23 06:19:05
MarkR
Mark Richardson
m.t.richardson2@gmail...
134.225.187.80

I pretty much do what Daniel does, I'm not so good with html :/

 

Lots of highlighting and using the delete key. And occasionally I go into the html and check the break and para tags and it sometimes fixes it... usually just trial and error though!

2011-01-23 09:53:32
Andy S

skucea@telus...
66.183.184.89

Glenn, thanks for this, it was interesting and well written.

I don't think that you should try to shorten it. Most people won't read a long article like this to the end but those who do will benefit from the longer explanations. I thought at first that it could be split up into two or more articles but on reflection, I don't think that's possible. I agree that most rebuttals on SkSc should be short and to the point but I see no reason why blog articles can't sometimes be much longer.

I do think that you need to emphasize that this is a thought experiment and that you can't really isolate most of the interconnected and moving parts of the Greenhouse system but that it's nevertheless instructive to try. For example, you can't have evapo-transpiration, which necessarily involves water vapour, if you don't have GHGs in the system (including water vapour) as in your step 3. If you don't spell this out up front, you'll end up having to argue the point N times in the comments.

Here are some niggly suggestions that may help readability and consistency:

1) It wasn't always clear on first reading whether the temperatures that you referred to were absolute temperatures or temperature differences. Usually you say things like 15 degrees C colder, which makes it clearbut not always and it's easy for the reader to get confused.

2) You usually use the degree symbol but sometimes you write "deg". I would also recommend that you remove the space between the number and the symbol to avoid them getting separated by an automatic line break.

3) The tables are a little inconsistent in the formatting, with some having single row height and others double, sometimes the numbers are left, right or centre justified and they should be consistent. ( Centre is best, I think). Also, you highlight the temperatures in red (this is helpful) in most tables but not in all of them.

4) Typos: Why is the temperature lowe if BR is now adding more heat to the surfacer?

Off-topic a bit: I have often wondered what the GH effect would be in a world without water. No clouds, no oceans or ice, no water vapour, no life, so no oxygen...

 

2011-01-24 06:22:02
Riccardo

riccardoreitano@tiscali...
93.147.82.140
Sorry for jumping in late.

ε is the still flipped in eq. 1
eq. 2 is unreadable. It should be -273.15. The T calculated in this way is called effective temperature. This effective temperature can be taken as a rough aproximation of the global average temperature.

In the table, it's not obvious why the reflected flux is 43.

Step 3. If you do not have absorption, ε=0 at all wavelength and you do not have any emission either, i.e. the atmosphere has no mechanism to give away the extra heat. The consequence is that you cannot have any temperature gradient, earth surface and atmosphere will have the same temperature and the atmosphere would be isothermal. The surface temperature will be the same as if the atmosphere was not there.

Step 4. Adding SW absorption does not change the picture much. Most of the energy absorbeded will end up as heat which can not be radiated away.

Step 6. "A photon can only travel a modest distance before it is absorbed by another molecule of something". This is true only where absorption bands of different molecules overlap.
2011-01-24 20:47:16
MarkR
Mark Richardson
m.t.richardson2@gmail...
192.171.166.144

A way of adding pictures using html which I jsut tried in my last post is  this.

 

You type LaTeX commands into the box and then it gives you the html underneath.

2011-01-25 14:54:25
Glenn Tamblyn

glenn@thefoodgallery.com...
124.181.128.239

Thanks Mark - The latex stuff works great. Right now I am trying to give the tables some luv. But they ain't giving much back.