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#221 indydave

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Posted 03 February 2016 - 06:15 PM

W:>>This suggests a positive feedback between surface temperatures and cloud development, the opposite to what you require.>>

 

I would think that positive feedback might mean MORE clouds.  What you and Pi need to show is NEGATIVE feedback.  If what is meant by "development" is "how tall they get" I could accept that as being true TODAY.  That is, the warmer the ocean, the more tall/developed the clouds will be.  But that is NOT saying what Pi says, (and what you have sometimes seemed to say) that there would be FEWER clouds when/where the ocean is warmer.  Are you ready to say clearly if you are in agreement with Pi about that?  However, if we try to hypothesize about the post-flood time, rather than TODAY, I would go with what Oard said about how the much more uniformly warmer ocean (post-flood) would not allow for tall development of clouds.  Your quotes from Journal of Climatology in no way address that unique post-flood situation.  At least Oard does try to directly focus on that idea.  And even IF you could show that the clouds were almost all of the cumulonimbus (tall, and "more developed") type, I believe you would agree with me that this would dramatically increase albedo...so all we have left to do is to discuss if the GE would be able to offset all the added albedo.  It would not.  You need about 21x the GE of today (if albedo went up from 30% today to 90%).  Doubling the air temp only increases water vapor to 2.4x.  Where does all the rest come from?  I don't think you've offered any explanation of that yet.

 

I do appreciate that you quoted the paper's equivocal statements...including both those that seem to support you and controvert you.  I will be reading through it and probably comment about it more soon.



#222 indydave

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Posted 03 February 2016 - 08:48 PM

Maybe it's just me, but this statement from that paper (right at the end) sure is confusing.

 

"This decline in MSC and the
warming of the sea surface, taken together with the
negative correlation between MSC and SST, suggests a
positive feedback to warming in regions of persistent
MSC."

 

It sounds to me that it is saying that the more SST (sea temp), the more MSC (low clouds) there will be (i.e. "positive feedback").  But other places in the paper it seems to say the opposite.  It also seems to suggest that there is no GLOBAL correlation.  It is positive in some places...negative in others. 

 

I will paste in other quotes and then highlight (bold) what I think is significant.

 

MSC therefore have a cooling effect
on climate [negative cloud radiative effect (CRE)].
Randall et al. estimated that a 4%increase in MSC cover
could offset a 28–38Cglobal temperature rise.
By contrast,
high (cirriform) clouds are thinner and colder, so their
longwave effect dominates, giving them a positive CRE.

 

WOW!  Did you get that?  It is saying that if you had a 32% increase in low clouds (from 25% today to 57%), you could expect that to be equal to 8 times that amount (8 times 28-32C) of cooling!  That seems like a LOT.  And of course they are (I think) including GE in that. 

 

They found that rising SST acts to destabilize the
marine boundary layer, eventually leading to the entrainment
of dry air
into the cloud deck and the replacement of
stratus cloud with cumulus.
 

It seems to me they are saying the CAUSE of the higher temps converting low level clouds to mid-level clouds is that the rising air pulls in (from the sides) the DRY air.  However in a post-flood state there would not BE any dry air over the very warm ocean!

the greatest cloud cover occurs during the season of highest
LTS. Wood and Hartmann (2006) also found that higher
cloud fractions occurred when LTS was greater.

Oard has said there would be more LTS (stability)...with low amounts of convection...so that the warm/moist air would stay low.  So with more stability then there would indeed be more lower clouds. 

 

Trenberth and Fasullo (2009) examined global climate
models for their changes in the earth’s radiation budget
between 1950 and 2010. The models were those used in
the Fourth Assessment Report of the Intergovernmental
Panel on Climate Change (IPCC). Their assessment
concludes that significant surface warming is expected
due to decreasing global cloud amounts.
Specifically, they
predict a decrease of low and middle clouds in midlatitudes
and a decrease of high clouds near the equator.
 

We were arguing about CAUSATION...which is the cart and which is the horse.  This ("DUE TO")seems to say that less clouds were the cause of the increased warming.  That's what I said. 

 

Total cloud cover appears to be steadily increasing in
Fig. 4a (see below) until 1998 when the time series begins a declining
trend. The same pattern is amplified in low cloud amount
in Fig. 4b.

 

That sure seems to contradict the chart we all were looking at a few pages back (post #140).  The low and high level clouds seem to increase while the mid level decrease....see this chart below.  This was a time of INCREASING global temps.  So that is when the global clouds INCREASED.  I don't know which chart to believe.  This one, or the one in #140 which shows lower clouds decreasing during that time period. 


Attached File  cloudfraction.jpg   53.68KB   0 downloads

A mechanism behind this relationship was hypothesized
by Wyant et al. (1997), whereby an increase in SST
causes a reduction in lower-tropospheric static stability.
The reduced stability allows for more vertical motion
within and around the cloud deck, leading to increased
entrainment of dry air.
This brings about a reduction in
cloudiness and a transition from stratiform to cumuliform
cloud types.
....This relationship was unique between low stratiform and
cumuliform cloud types, suggesting that these two types
tend to trade-off, meaning that in a given year or season
one type is consistently more common at the expense of
the other.


The central Pacific is the only one of the six regions in
which cloud cover correlates positively with SST....It is likely that in this region
convection is driven by SST, and the warmer the sea
surface, the stronger and deeper the convection, leading
to greater and more persistent cloud cover at all
levels.

 

I realize this says only one of 6 regions have positive correlation, however this region is the WARMEST...the central Pacific.  So more warm air there WILL cause more lower level clouds.  In fact it has more of all types except cumulus.  That is the exact region where Pi predicted that we should see FEWER clouds.  Remember when he questioned this pic...if it was in the warmer or colder part of the Pacific?

 

stratuspic.jpg



#223 indydave

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Posted 03 February 2016 - 10:21 PM

BTW, Pi, you have said several times that you will go with what NOAA or NASA say, rather than your teacher's assn (NESTA).  You mocked me by saying the data on a page I PROVIDED to you helped you make your point that higher global temps will cause lower amounts of clouds.  Well, that page (LINK) was not a NASA or NOAA page.  But if you want to use it as an authority over NESTA then you should also note that the same page says THIS: 

 

Water vapour is the single most important greenhouse gas, wherefore it is interesting to note that global warming since 1978 apparently terminated in 1998, simultaneously with the step-like decrease in atmospheric water vapour content. Global climate models forecast an increasing amount of atmospheric water vapour along with global temperature increase.



#224 indydave

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Posted 03 February 2016 - 11:28 PM

It appears that NASA can't make up its mind:  LINK

 

"If the climate should change, then clouds would also change, altering all of the effects listed above. What is important is the sum of all these separate effects, the net radiative cooling or warming effect of all clouds on Earth. For example, if Earth's climate should warm due to the greenhouse effect , the weather patterns and the associated clouds would change; but it is not known whether the resulting cloud changes would diminish the warming (a negative feedback) or enhance the warming (a positive feedback). Moreover, it is not known whether these cloud changes would involve increased or decreased precipitation and water supplies in particular regions. Improving our understanding of the role of clouds in climate is crucial to understanding the effects of global warming.

 

And:  "Moreover, changes in any of these climatic features may also affect the distribution and properties of clouds , but the understanding of clouds is so rudimentary that no one knows whether climate feedbacks involving clouds will dampen or amplify a warming trend. The possibility that clouds might accelerate global warming brings a special urgency to the ancient problem of understanding the climatic importance of clouds."

 

More: "For example, if cloud cover were to increase (as many thought it would, assuming that warmer temperatures would speed evaporation), the amount of sunlight reaching Earth's surface would decrease, but then the thermal radiation trapped by the cloud might increase by the same amount. Even such a simple scenario has problems, though. Because the decrease in solar heating would affect surface temperatures, whereas the change in the emission of thermal radiation would affect air temperatures at higher altitudes, additional cloud cover would reduce the temperature contrasts between the surface and the higher altitudes that drive the winds. Any reduction of winds might in turn inhibit the formation of clouds. The early studies did not account for this possibility.  (Indy: notice, the simpler idea was warmer = more clouds, but some doubted that if there was less wind).  Another idea is that higher atmospheric temperatures could create denser clouds, since greater evaporation rates at higher temperatures would make more water vapor available in the atmosphere for cloud condensation. Because denser clouds reflect more sunlight, there would be an enhanced cooling effect. (Indy: note that it was not a question of if more clouds form if it is warmer) This would reduce the magnitude of the greenhouse warming. On the other hand, denser clouds might also lead to an increase in precipitation (rainfall and snowfall), possibly from storm clouds, whose tops are especially high and cold. Such clouds, which are particularly good absorbers of thermal radiation, could more than make up for their tendency to block sunshine. In that case the warming would be intensified. (Indy: so again it is not a question whether warmer = more clouds...it is just about if the GE warming will offset the cooling). 

 

And: "The cloudiest regions are tropics   (Indy: this surely seems to contradict what both Pi and Wibble have said). And the temperate midlatitude storm zones; the subtropics and the polar regions have 10-20% less cloud cover....High-latitude clouds are almost twice as reflective as most clouds at lower latitudes.  (Indy: so I guess there are less of them but they are more reflective...so maybe that's why the maps are brighter white at the poles while MORE clouds are at the equator)....Meteorologists have long associated greater cloud cover, higher cloud tops and denser, more reflective clouds with regions of more vigorous storms. Both the tropics and the low-pressure areas at midlatitudes are regions of severe weather."

 

Also:

 

"The process traps heat like a blanket and slows the rate at which the surface can cool by radiation. The blanketing effect warms Earth's surface by some 7°C (13°F)."

 

To me, this suggests that if you tripled the lower level clouds from about 28% now to 84%...that would cause a 21C warming effect.  However, if you triple the albedo to 84%, then you get 90C worth of cooling (acc. to the albedo calc site).  Subtracting the two gives you a net 69C of cooling.  If you doubled, then there would be 14C of warming to offset 33C of cooling...for a net temp change of -19.  Or a global avg temp of -4C.  That's pretty close to the 0C figure I suggested during the ice age. The quote from this NASA page surely supports my idea. 

 

OK Pi...I've supplied quotes from NASA's International Satellite Cloud Climatology Project (ISCCP) which show that warmer oceans cause more clouds.  Or at the least, they can't make up their mind about it.  Now it's your turn to show quotes from them saying warmer oceans cause FEWER clouds.  Go right ahead. 

 

OR...you can admit you are wrong. 



#225 indydave

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Posted 03 February 2016 - 11:45 PM

I saw this:

LINK

"A mean temperature rise of just 0.1 degrees Celsius in oceans corresponds to a temperature increase of 100 degrees Celsius in the atmosphere if all the heat associated with the ocean anomaly was transferred into the atmosphere."

 

This says to me that if you lost 1C from the ocean in one year, then it would heat up the atm by 1000C.  Or if you lost .001C from the ocean, it would raise the atm by 1C.  So if you lost (say) 15C from the ocean in 700 years (to cool it from 30C to 15C) that means that you would be supplying .021C per year from the ocean to heat the atm.  If you multiply that by 1000 that gives you 21C per year of heat from the ocean added to the atm to replace whatever is lost due to increased albedo (lost solar influx).  Acc to the albedo site, an albedo of 47 would exactly equal 21C of cooling.  If you had (say) an addition 10C of cooling, that could be enough to cause an ice age.  Maybe even just 7C or so would. (That's what I think we are told was the coldest temp.)  An albedo of 55 would give you that extra 10C of cooling. 

 

I was thinking of trying that calc myself, to figure the mass of the ocean vs. the atm and the specific heat of water vs. air, but finding this quote (if it's right) saved me a lot of effort!



#226 indydave

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Posted 04 February 2016 - 11:23 AM

Pi>>Both statements were supported by an explanation from NOAA showing the development of such storms takes place over warm waters when converging air masses collide. Oard's model is based on LOTS of warm water. IIRC, you have pretty much acknowledged Oard probably wouldn't argue too much about the increase and severity of tropical storms.<

No, he has said and I have posted here that he would say that with a warmer ocean there would be few taller clouds and more low clouds.

>> 1) I didn't say a warmer ocean will cause clear skies, just fewer clouds. <

Really? You want to quibble over my not saying clearER instead of clear? Everyone knew I wasn't talking about perfectly clear sky including you. But I guess that's your best argument in defense of your having spoken out of both sides of your mouth on this. How can you have more storms without more clouds?

>1) Clouds and water vapor are competing feedback loops.
2) Predicting the net influences of them is one of the big problems of climate prediction.
3) One loop is a positive feedback due to increased water vapor.
4) The other loop is a negative feedback due to increased cloud cover.
5) Scientists don't know which of these will dominate.<<

Yes of course sometimes they will admit to this not being clear. Other times they speak as if they know for sure there could be catastrophic warming. But what is under no dispute by them is whether warmer temperatures will cause more clouds. At least not in this quote from NESTA. Their question was about whether the increased clouds would cause enough warming to offset all the cooling.

>>or that they aren't relevant to the point we're (still) working on.... the increased cloud-cover that seems to be a requirement of Oard's model.<<

No, increased clouds to cause cooling is definitely NOT any requirement at all for his model. I have suggested increased clouds could also play a part in causing greater albedo and cooling. Not Oard.

#227 indydave

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Posted 04 February 2016 - 12:43 PM

I wrote:

Maybe it's just me, but this statement from that paper (right at the end) sure is confusing.

"This decline in MSC and the
warming of the sea surface, taken together with the
negative correlation between MSC and SST, suggests a
positive feedback to warming in regions of persistent
MSC."

It sounds to me that it is saying that the more SST (sea temp), the more MSC (low clouds) there will be (i.e. "positive feedback"). But other places in the paper it seems to say the opposite.
===

Ok, I can see now that the idea of positive feedback the paper spoke of was between clouds and warming. At the same time it spoke of a negative feedback or negative correlation between warm oceans and clouds. I think it is legitimately confusing however I guess it could mean that the warm oceans cause fewer low level clouds and then the fewer clouds will allow more solar radiation in and that will cause warming.

I still think that paper is equivocal.

#228 wibble

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Posted 06 February 2016 - 04:40 PM

First I want to point out something in your reply to Piasan
 

And: "The cloudiest regions are tropics (Indy: this surely seems to contradict what both Pi and Wibble have said). And the temperate midlatitude storm zones; the subtropics and the polar regions have 10-20% less cloud cover....


This is the original quote:

"The cloudiest regions are tropics and the temperate midlatitude storm zones; the subtropics and the polar regions have 10-20% less cloud cover."

Why did you split the sentence to make it look like it was saying that the tropics are cloudier than the temperate mid latitude storm zones ?
 

W:>>This suggests a positive feedback between surface temperatures and cloud development, the opposite to what you require.>>

I would think that positive feedback might mean MORE clouds. What you and Pi need to show is NEGATIVE feedback. If what is meant by "development" is "how tall they get" I could accept that as being true TODAY. That is, the warmer the ocean, the more tall/developed the clouds will be.


Yes taller clouds not more surface covered. So you accept that as true today, good.
 

But that is NOT saying what Pi says, (and what you have sometimes seemed to say) that there would be FEWER clouds when/where the ocean is warmer.


I think Piasan has expressed uncertainty, which is the correct thing. Warmer air can hold more moisture and therefore could potentially produce more cloud. On the other hand warmer air is able to hold more moisture without it condensing.
 

However, if we try to hypothesize about the post-flood time, rather than TODAY, I would go with what Oard said about how the much more uniformly warmer ocean (post-flood) would not allow for tall development of clouds.

uragan-system.jpg

The storm clouds produce their own cool, dry air from the top of the system. It's an engine working off the heat of the ocean to produce wind and rain. Doesn't matter how uniformly warm the ocean is.


And even IF you could show that the clouds were almost all of the cumulonimbus (tall, and "more developed") type, I believe you would agree with me that this would dramatically increase albedo...so all we have left to do is to discuss if the GE would be able to offset all the added albedo.


You’ve learnt since the early stages of this thread that tall clouds (like cumulonimbus) have a neutral effect on temperature. How have you now forgotten that ?

Besides, stratus already has a high albedo (although interestingly the Eastman paper states that it is only 40-50 %). Replacing that with cumulus type, as the paper indicates would happen as cooler ocean areas warm, would promote heating (neutral clouds plus more gaps in those clouds letting sunlight through)
 

MSC therefore have a cooling effect on climate [negative cloud radiative effect (CRE)]. Randall et al. estimated that a 4%increase in MSC cover could offset a 28–38Cglobal temperature rise.

WOW! Did you get that? It is saying that if you had a 32% increase in low clouds (from 25% today to 57%), you could expect that to be equal to 8 times that amount (8 times 28-32C) of cooling! That seems like a LOT.


Yes it is a lot if you completely change what was said in the paper. Here’s what it says:

Randall et al. (1984) estimated that a 4% increase in MSC cover could offset a 2-3°C global temperature rise.

I don’t understand how you’ve done that ?
 

It seems to me they are saying the CAUSE of the higher temps converting low level clouds to mid-level clouds is that the rising air pulls in (from the sides) the DRY air. However in a post-flood state there would not BE any dry air over the very warm ocean!


Oard has said there would be more LTS (stability)...with low amounts of convection...so that the warm/moist air would stay low. So with more stability then there would indeed be more lower clouds.


I refer you again to the chart earlier. If Oard really thinks that tall clouds can’t form over a warm oceans then he’s talking rubbish. No other meteorologist would say that.
 

“The central Pacific is the only one of the six regions in which cloud cover correlates positively with SST....It is likely that in this region convection is driven by SST, and the warmer the sea surface, the stronger and deeper the convection, leading to greater and more persistent cloud cover at all levels.”

I realize this says only one of 6 regions have positive correlation, however this region is the WARMEST...the central Pacific. So more warm air there WILL cause more lower level clouds.


It says cloud at all levels. Not just low clouds. So insignificant net feedback due to clouds on temperature.
 

"The process traps heat like a blanket and slows the rate at which the surface can cool by radiation. The blanketing effect warms Earth's surface by some 7°C (13°F)."

To me, this suggests that if you tripled the lower level clouds from about 28% now to 84%...that would cause a 21C warming effect.However, if you triple the albedo to 84%, then you get 90C worth of cooling (acc. to the albedo calc site). Subtracting the two gives you a net 69C of cooling. If you doubled, then there would be 14C of warming to offset 33C of cooling...for a net temp change of -19. Or a global avg temp of -4C. That's pretty close to the 0C figure I suggested during the ice age.


Cloud does not supply the entire albedo of the planet, Deserts for example have an albedo of 0.3, any surface will have some albedo. The average albedo of Earth is 0.31. So how is tripling clouds from 28% going to triple the total albedo ?

Also, talk of 90C cooling due to cloud albedo is nonsensical. The Earth would be 12C warmer if there were no clouds (net effect incl. GE is 5C cooling at the surface). So the albedo effect of current cloud cover of 60% allows for 12C cooling. Forgetting GE that suggests that 100% cover gives 100/60 x 12 = 20C

But none of that matters anyway because you still haven’t shown why low clouds would drastically increase and cirrus disappear in your hot ocean scenario. All the observational data that has been presented in this thread and the content of the Journal of Climatology paper shows that there is no justification for that idea (and that paper is no way equivocal as you bizarrely state).

You promised in post #210 that you would demonstrate how hot oceans produce your low cloud/no high cloud scenario....



#229 indydave

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Posted 09 February 2016 - 08:04 AM

I said I would demonstrate when you have demonstrated, and you demonstrated nothing. All you did was give your hypothetical reasoning for why you think something about the Gulfstream from the past. And I gave my reasoning as well. How does anyone demonstrate anything from the past?

#230 indydave

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Posted 09 February 2016 - 08:11 AM

Maybe it would help a lot if you would demonstrate why it is that if just one large volcano can drop global temperatures for 2 years by 1C or even 5C as we are told about one from 75000 years ago, why would it be that having 100 or 1000 volcanoes would NOT drop temperatures significantly for a long enough time to launch an ice age? Explain that. No...DEMONSTRATE that.

#231 indydave

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Posted 09 February 2016 - 08:14 AM

Also while we're on this subject, is it your opinion that all of the assumptions of evolution and ancient earth have been DEMONSTRATED?

Or do you think maybe you should have used a different word?




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