Greenhouse Effect Discussion

[TerryM]

I'm not sure who you're referring to but what I am trying to ask is why you assume the greenhouse effect is solely radiative in nature. There are physics that suggest otherwise.

I've done a fair amount of research and came up with a different conclusion, hence my questioning.

Since you've already reached a conclusion why are to asking questions?

Tell us your new theory and we can discuss that - as opposed to answering a barrage of questions.

Terry

[physicsguy21]

Since you've already reached a conclusion why are to asking questions?

Tell us your new theory and we can discuss that - as opposed to answering a barrage of questions.

Terry

I was just trying to figure out where our ideas diverged. My hypothesis is very similar to that of Ned Nicklov's 'unified theory of climate', relating the gravity induced lapse rate, air pressure, and distance from the Sun to a planetary temperature.

I can see when I'm not wanted though, so I'll depart.

[Jonger]

Lets just figure a way to sequester CO2 out of the atmosphere and be on the safe side, all other discussions and scare charts really accomplish nothing at this point.

[cmc0605]

I was just trying to figure out where our ideas diverged. My hypothesis is very similar to that of Ned Nicklov's 'unified theory of climate', relating the gravity induced lapse rate, air pressure, and distance from the Sun to a planetary temperature.

I can see when I'm not wanted though, so I'll depart.

It's complete nonsense, and not a very good starting point for good discussions about what controls planetary climate. I'm new here so I won't speak for anyone, but my quick impression is that you're in a much different world than somewhere like WUWT that will post any crackpot idea as long as it has some connection to why humans can't influence the climate much- whether it be because we don't influence GHG concentrations, because greenhouse effects aren't real, because the CO2 effect is small, because other things cause warming, because we can't measure the warming, because sensitivity is small, or whatever other half thought out and contradictory ideas someone comes up with..

My suggestion for understanding principles like the ideal gas law, the lapse rate, etc is to consult some basic texts on climate...Dennis Hartmann's is a great start, Marshall and Plumb, Houghton, and Ray Pierreumbert for one of the best treatments. For intro thermodynamics, Grant Petty's book is good, and he also has an intro radiation book. All require a bit of calculus, but nothing more.

[WeatherRusty]

This is as good a place as any to answer questions implied by both skier and physicsguy21. Rather than in my usual style of putting it to my own words, here is a bit from Chris Colose's now dead blog which describes the greenhouse effect and the radiative forcing of climate as well as anywhere and in easily understood terms. Enjoy....

In the easiest case, we’ll consider what happens when you only increase some forcing (say double CO2) and allow the outgoing radiation to increase (according to the Stefan-Boltzmann law) to re-establish a new radiative equilibrium. Here, nothing else changes with the climate state (no cloud cover changes, no ice melts, etc) except for our forcing. This is the so-called Planck response. In a simple way, we can assume that the surface and emission temperature are linearly related, in which case the Planck-only feedback response can be computed as the inverse of the derivative of Stefan-Boltzmann with respect to temperature,

Which equals,

SEE Source below for equation

The temperature response can then be linearly related to a forcing

See Source below for equation

Where lambda is the Planck-feedback factor described above. It is important to note now that this is an equilibrium formula, meaning that we don’t see the full temperature response to show up right away if we instantly double CO2, since it takes time for the radiative imbalance to go to zero (it’s hard to heat up the oceans quickly!). We’ll see that when we actually allow other things like clouds,water vapor, albedo, etc to vary with the climate response (as opposed to the unrealistic stefan-boltzmann only feedback), then lambda becomes a function of all those things, and describes how the total forcing is connected to the temperature response. This formula implies that for a 4 Watt per square meter forcing (remember, about a doubling of CO2 equivalent), you get roughly a 1 K temperature rise (multiply these numbers by two to get changes in Fahrenheit).

To compute a radiative forcing for an increase in solar irradiance, we do

See Source below for equation

where the 1/4 and 0.7 factor account for the geometry and albedo of the Earth, respectively. Depending on how radiative forcing is defined, this number can often be reduced further to account for ozone absorption of UV or other effects, but in general the forcing due to a realistic change in solar increase is very small. It follows that it would take about a 22 W/m² change in solar irradiance to produce a 1 K change in global temperature. This is actually a very stable climate. This also demonstrates the intellectual bankruptcy of those who claim that the solar trend over the last half century (which has pretty much been a flat-line when you remove the 11-year oscillatory signal) is responsible for most of the observed late 20th century warming, and simultaneously argue for a low sensitivity.

Source ........(you'll want to bookmark it for future reference, it's that good!)

The Planck response is the often cited 1.2C of global warming caused by a doubling of CO2 before any feedback. This response works out to a bit less than 0.3C per watt of forcing....from any source. Notice that the Sun would have to increase in radiance by 22W/m^2 to equal a radiative forcing of 3.7W/m^2.

[physicsguy21]

It's complete nonsense, and not a very good starting point for good discussions about what controls planetary climate. I'm new here so I won't speak for anyone, but my quick impression is that you're in a much different world than somewhere like WUWT that will post any crackpot idea as long as it has some connection to why humans can't influence the climate much- whether it be because we don't influence GHG concentrations, because greenhouse effects aren't real, because the CO2 effect is small, because other things cause warming, because we can't measure the warming, because sensitivity is small, or whatever other half thought out and contradictory ideas someone comes up with..

My suggestion for understanding principles like the ideal gas law, the lapse rate, etc is to consult some basic texts on climate...Dennis Hartmann's is a great start, Marshall and Plumb, Houghton, and Ray Pierreumbert for one of the

best treatments. For intro thermodynamics, Grant Petty's book is good, and he also has an intro radiation book. All require a bit of calculus, but nothing more.

Well your assumptions about me are wrong, I hadn't even gone into detail and you're already badgering me with claims. What is your scientific basis for calling UTC 'nonsense'? The conservation of energy is not violated if you're referring to that.

There is no 240wm2 global net insolation, it is 480wm2 spanning 1/2 of the globe, more than enough to keep the oceans heated to near present day levels. The surface warms to a higher value than the MSAT under solar radiation, conduction is the principle heat transfer mechanism for over 99% of atmospheric molecules..backradiation consitutes a small portion of energy transferred to the surface at night.

Please explain why the radiative greenhouse effect is the sole variable in attaining the 33C warming over the S-B constant.

[WeatherRusty]

Well your assumptions about me are wrong, I hadn't even gone into detail and you're already badgering me with claims. What is your scientific basis for calling UTC 'nonsense'? The conservation of energy is not violated if you're referring to that.

There is no 240wm2 global net insolation, it is 480wm2 spanning 1/2 of the globe, more than enough to keep the oceans heated to near present day levels. The surface warms to a higher value than the MSAT under solar radiation, conduction is the principle heat transfer mechanism for over 99% of atmospheric molecules..backradiation consitutes a small portion of energy transferred to the surface at night.

Please explain why the radiative greenhouse effect is the sole variable in attaining the 33C warming over the S-B constant.

If the Earth had no atmosphere it's average surface temperature would sit at about 255K, it's gray body Stefan-Boltzmann derived temperature. Do you agree with that?

Greenhouse gases such as water vapor and carbon dioxide do not account for the whole of the greenhouse effect. Clouds are estimated to provide about 25% to the greenhouse effect. Clouds are not water vapor, they are liquid water and ice. There are aerosols which impede the flow of Earth's thermal radiation back out to space. Everything else is just window dressing. The net effect of all which makes up the atmosphere is a greenhouse effect equaling 33C.

Regardless of all conduction and convection within the troposphere, the energy flow measured at the tropopause and above is essentially all radiative. That is why radiative forcing is defined as the energy flux taken at the tropopause. Conduction and convection are not significant factors any longer in the transfer of surface radiation from above the troposphere.

If the world had no open surface water from which to evaporate water vapor, the greenhouse effect would be much reduced, lapse rates would be steeper, there would be no water clouds. The Earth does have oceans however. So no, the radiative portion of the greenhouse isn't everything, but it is the one thing that we are changing the most and that is why it is important.

[physicsguy21]

If the Earth had no atmosphere it's average surface temperature would sit at about 255K, it's gray body Stefan-Boltzmann derived

temperature. Do you agree with that?

Yes, if there were no atmosphere or oceans.

Greenhouse gases such as water vapor

and carbon dioxide do not account for the whole

of the greenhouse effect. Clouds are estimated to provide about 25% to the greenhouse effect.

Clouds are not water vapor, they are liquid water and ice. There are aerosols which impede the

flow of Earth's thermal radiation back out to space. Everything else is just window dressing.

The net effect of all which makes up the atmosphere is a greenhouse effect equaling 33C.

Regardless of all conduction and convection within the troposphere, the energy flow measured at the tropopause and above is essentially all radiative. That is why radiative forcing is defined as the energy flux taken at the

tropopause. Conduction and convection are not significant factors any longer in the transfer of

surface radiation from above the troposphere.

Having an atmosphere constantly conducting heat to the surface at night keeps it warmer than it would otherwise be to begin the next day's heating cycle, it acts as a form of insulation. Slowing the cooling of surface temperature is

how the greenhouse effect operates. Only a tiny portion of the 'heat' the atmosphere transfered to the surface at night is in the form of backradiation initially.

If the world had no open surface water from which to evaporate water vapor, the greenhouse effect would be much reduced,

lapse rates would be steeper, there would be no water clouds. The Earth does have oceans however. So no, the radiative portion of the greenhouse isn't everything, but it is the one

thing that we are changing the most and that is why it is important.

Would you agree that our 480wm2 insolation over 1/2 the globe is enough to maintain our current oceanic state? Backradiation can only penetrate about 0.25mm deep into water. Evaporation, cloud cover, and precipitation actually work to keep the oceans cooler than they would otherwise be since clouds reflect Shortwave radiation that penetrates below the evaporative surface sheet.

[WeatherRusty]

Yes, if there were no atmosphere or oceans.

Having an atmosphere constantly conducting heat to the surface at night keeps it warmer than it would otherwise be to begin the next day's heating cycle, it acts as a form of insulation. Slowing the cooling of surface temperature is

how the greenhouse effect operates. Only a tiny portion of the 'heat' the atmosphere transfered to the surface at night is in the form of backradiation initially.

Would you agree that our 480wm2 insolation over 1/2 the globe is enough to maintain our current oceanic state? Backradiation can only penetrate about 0.25mm deep into water. Evaporation, cloud cover, and precipitation actually work to keep the oceans cooler than they would otherwise be since clouds reflect Shortwave radiation that penetrates below the evaporative surface sheet.

We agree to most of this. As I have stated earlier, the back radiation from the atmosphere does not warm the ocean water. The atmospheric blanket serves to slow the loss of heat from the surface. The net flow of energy is outward as both the atmosphere and surface exchange energy with each other. Solar insolation during the daylight hours is what warms the water.

The oceans are left warmer than they would be absent a greenhouse effect. That is not the same as saying the greenhouse effect warms the water. The effect is a warmer ocean, the process is still a net loss of energy to space, until the Sun does it's thing during the day. You say 480wm2 insulation does the trick., well....240W directly from the Sun is sufficient to to maintain constant temp also, provided the greenhouse effect and everything else remains the same. It must be realized also, that the values given for the Earth's energy budget are time and spatially integrated. They are not instantaneous values.

While evaporation, clouds and precipitation cool the local environment, this is essentially a wash because those processes are only taking back the energy that went into evaporating the water in the first place.

[physicsguy21]

We agree to most of this. As I have stated earlier, the back radiation from the atmosphere does not warm the ocean water. The atmospheric blanket serves to slow the loss of heat from the surface. The net flow of energy is outward as both the atmosphere and surface exchange energy with each other. Solar

insolation during the daylight hours is what warms the water.

The oceans are left warmer than they would be absent a greenhouse effect. That is not the same as saying the greenhouse effect warms the water. The effect is a warmer ocean, the process is still a net loss of energy to space,

until the Sun does it's thing during the day. You say 480wm2 insulation does the trick., well....240W directly from the Sun is sufficient to to maintain constant temp also, provided the

greenhouse effect and everything else remains the same. It must be realized also, that the

values given for the Earth's energy budget are time and spatially integrated. They are not instantaneous values.

While evaporation, clouds and precipitation cool the local environment, this is essentially a wash because those processes are only taking back

the energy that went into evaporating the water

in the first place.

Thank you for the response. I think the one thing you're forgetting is that during the act of

convection, molecules are overcoming gravity which requires energy, heat is exchanged for necessary mechanical processes. It appears that much of what we call the greenhouse effect is driven by gravity through molecular line broadening. The manner in which the total energy budget is determined contains quite a few errors in my opinion. It is really much larger.

I completely agree with you in that backradiation slows ocean cooling, but this forcing is small compared to collision which accounts for over 99% of the heat transfer from the atmosphere to the surface, on a molecular scale.

[skierinvermont]

:lmao:

there is no doubt this is BethesdaBoy.

Yep, it's BB.

[TerryM]

Yep, it's BB.

Possibly under a number of spoofed names?

[physicsguy21]

:lmao:

there is no doubt this is BethesdaBoy.

I have no idea what you're talking about.

[WeatherRusty]

I have no idea what you're talking about.

Separated at birth maybe?

[WeatherRusty]

If one of the goals of science is to reduce complex problems to more understandable, simpler terms then looking at how a body/planet floating in the vacuum of space reaches thermodynamic equilibrium with the radiation from it's Sun is a perfect example. Regardless of all the complicating interactions occurring at the near surface environment of Earth, the temperature the surface arrives at in an equilibrium state is determined by only two quantifiable factors. The total energy absorbed by the body divided by the total energy of emission from the body. If one or the other value is larger then the body is not in thermal equilibrium with the radiation flux and will either warm or cool until equilibrium is established.

In the case of the present day Earth, careful measurement indicates that the Earth is currently absorbing more energy from the Sun than it is radiating back to space. So we know the Earth must currently be accumulating energy which eventual will drive up surface temperature so that the total energy emitted by Earth equals the energy it is receiving. We know this to be the case as a consequence of Stefan-Boltzmann Law which state that the total energy emitted by a body is proportional to the forth power of it's temperature. The warmer the body the greater it's rate of emission at all electromagnetic wavelengths (Planck's Law).

There are only 2 substantial sources of energy which irradiate the Earth's surface. The primary source of course being the Sun, the other being Earth's own atmosphere.

All energy emitted by the Earth is in the form of radiation, either directly from the surface or from within the atmosphere.

So we see that the Earth's atmosphere plays a very important role in establishing the surface temperature of the Earth.

Over the past several decades the output of the Sun has decreased by a small amount. So the Earth is not receiving greater energy from the Sun. Yet, the energy balance on Earth indicates the Earth must be warming. If not the Sun, then the only other source of energy to explain the energy imbalance is the Earth's own atmosphere. The atmosphere however, does not produce energy like the Sun. It's role is to maintain a warmer surface by slowing down the loss of energy to space. The atmosphere produces a greenhouse effect.

I think we all know the rest of this story!

[dabize]

If one of the goals of science is to reduce complex problems to more understandable, simpler terms then looking at how a body/planet floating in the vacuum of space reaches thermodynamic equilibrium with the radiation from it's Sun is a perfect example. Regardless of all the complicating interactions occurring at the near surface environment of Earth, the temperature the surface arrives at in an equilibrium state is determined by only two quantifiable factors. The total energy absorbed by the body divided by the total energy of emission from the body. If one or the other value is larger then the body is not in thermal equilibrium with the radiation flux and will either warm or cool until equilibrium is established.

In the case of the present day Earth, careful measurement indicates that the Earth is currently absorbing more energy from the Sun than it is radiating back to space. So we know the Earth must currently be accumulating energy which eventual will drive up surface temperature so that the total energy emitted by Earth equals the energy it is receiving. We know this to be the case as a consequence of Stefan-Boltzmann Law which state that the total energy emitted by a body is proportional to the forth power of it's temperature. The warmer the body the greater it's rate of emission at all electromagnetic wavelengths (Planck's Law).

There are only 2 substantial sources of energy which irradiate the Earth's surface. The primary source of course being the Sun, the other being Earth's own atmosphere.

All energy emitted by the Earth is in the form of radiation, either directly from the surface or from within the atmosphere.

So we see that the Earth's atmosphere plays a very important role in establishing the surface temperature of the Earth.

Over the past several decades the output of the Sun has decreased by a small amount. So the Earth is not receiving greater energy from the Sun. Yet, the energy balance on Earth indicates the Earth must be warming. If not the Sun, then the only other source of energy to explain the energy imbalance is the Earth's own atmosphere. The atmosphere however, does not produce energy like the Sun. It's role is to maintain a warmer surface by slowing down the loss of energy to space. The atmosphere produces a greenhouse effect.

This should be required reading for all who post here. The bolded phrase encapsulates perfectly the entire field of view of all AGW deniers/downplayers.

It is a very small pond, full of weeds, with no outlet to the sea (or to anything else that matters)...................