Archives par mot-clé : Clouds

Clouds From Both Sides Now

by W. Eschenbach, March 15, 2021 in WUWT

Clouds are said to be the largest uncertainty in climate models, and I can believe that. Their representation in the models is highly parameterized, each model uses different parameters as well as different values for the same parameters, and so of course, different models give very different results. Or to quote from the IPCC, the Intergovernmental Panel on Climate Change:

In many climate models, details in the representation of clouds can substantially affect the model estimates of cloud feedback and climate sensitivity. Moreover, the spread of climate sensitivity estimates among current models arises primarily from inter-model differences in cloud feedbacks. Therefore, cloud feedbacks remain the largest source of uncertainty in climate sensitivity estimates.

The question of importance is this—if the earth heats up, will clouds exacerbate the warming or will they act to reduce the warming? The general claim from mainstream climate scientists and the IPCC is that the clouds will increase the warming, viz:

All global models continue to produce a near-zero to moderately strong positive net cloud feedback.

My own theory is that clouds and other emergent climate phenomena generally act to oppose any increases in surface temperature. So me, I’d expect the opposite of what the models show. I figured that there should be a negative cloud feedback that opposes the warming.

So I thought I’d take a look at answering the question using the CERES satellite dataset. As a prologue, here’s a short exposition about measuring the effect of clouds.

The natural ‘Himalayan aerosol factory’ can affect climate

by University of Helsinki, Dec 10, 2020 in WUWT

Large amounts of new particles can form in the valleys of the Himalayas from naturally emitted gases and can be transported to high altitudes by the mountain winds and injected into the upper atmosphere.

The emitted particles may eventually affect climate by acting as nuclei for cloud condensation. These new findings about particles formation and sources will contribute to a better understanding of past and future climate.

“To understand how the climate has changed over the last century we need to know as reliably as possible the natural atmospheric conditions before the industrialization,” says Associate Professor Federico Bianchi from the University of Helsinki’s Institute for Atmospheric and Earth System Research (INAR).

In order to do that scientists are looking for pristine locations around the world where human influence is minimal. An international group of researchers has now completed a comprehensive study at the Nepal Climate Observatory at Pyramid station, located in the proximity of the Everest base camp at 5050 m above sea level. There, they were able to investigate the formation of atmospheric particles far from human activities. The results were published today in the prestigious journal Nature Geoscience.

Climate Scientists Admit Clouds are Still a Big Unknown

by E. Worrall, Sep 12, 2020 in WUWT

The authors assert that if we had a better understanding clouds, the spread of model predictions could be reduced. But there is some controversy about how badly cloud errors affect model predictions, and that controversy is not just limited to climate alarmists.

Pat Frank, who produced the diagram at the top of the page in his paper “Propagation of Error and the Reliability of Global Air Temperature Projections“, argues that climate models are unphysical and utterly unreliable, because they contain known model cloud physics errors so large the impact of the errors dwarfs the effect of rising CO2. My understanding is Pat believes large climate model physics errors have been hidden away via a dubious tuning process, which adds even more errors to coerce climate models into matching past temperature observations, without fixing the original errors.

Climate skeptic Dr. Roy Spencer disagrees with Pat Frank; Dr. Spencer suggests the cloud error biases hilighted by Pat Frank are cancelled out by other biases, resulting in a stable top of atmosphere radiative balance. Dr. Spencer makes it clear that he also does not trust climate model projections, though for different reasons to Pat Frank.

Other climate scientists like the authors of the study above, Paulo Ceppi and Ric Williams, pop up from time to time and suggest that clouds are a significant problem, though Paulo and Ric’s estimate of the scale of the problem appears to be well short of Pat Frank’s estimate.

Whoever is right, I think what is abundantly clear is the science is far from settled.

California’s Creek Fire Creates Its Own Pyrocumulonimbus Cloud

by NASA, September 9, 2020 in WUWT

On Friday September 4, 2020 at about 6:44 PM PDT the Creek Fire began in the Big Creek drainage area between Shaver Lake, Big Creek and Huntington Lake, Calif. NASA’s Suomi NPP satellite captured these images of the fire on Sep. 05 through Sep. 07, 2020. From the series of images the spread of the fire can be seen in the outward movement of the red hot spots, although the huge cloud on the 6th obscures all readings due to its size.

The huge, dense cloud created on Sep. 05 and seen in the Suomi NPP image was a pyrocumulonimbus cloud (pyroCb) and the resulting smoke plume that grew upward was spotted and confirmed on Sep. 06, 2020. A pyrocumulonimbus cloud is also called a cumulonimbus flammagenitus. The origins of the latter word are from the Latin meaning “flame” and “created from.” This perfectly describes a cloud that is caused by a natural source of heat such as a wildfire or volcano. Rising warm air from the fire can carry water vapor up into the atmosphere causing clouds. Any type of convective cloud can be created. In this case, the cumulonimbus, or thunderhead cloud, was created. Precipitation and lightning can also occur with these types of clouds creating a risk that the fire will expand due to increased wind from precipitation downdraft or by creating new fires due to lightning strikes. These are all things that fire managers must keep in mind while continuing to try to fight the fire.

Scientists: It’s ‘Impossible’ To Measure Critical Cloud Processes…Observations 1/50th As Accurate As They Must Be

by K. Richard, August 20, 2020 in NoTricksZone

Clouds dominate as the driver of changes in the Earth’s radiation budget and climate. A comprehensive new analysis suggests we’re so uncertain about cloud processes and how they affect climate we can’t even quantify our uncertainty. 

According to scientists (Song et al., 2016), the total net forcing for Earth’s oceanic atmospheric greenhouse effect (Gaa) during 1992-2014 amounted to -0.04 W/m² per year. In other words, the trend in total longwave forcing had a net negative (cooling) influence during those 22 years despite a 42 ppm increase in CO2. This was primarily due to the downward trend in cloud cover that overwhelmed or “offset” the longwave influence from CO2.

Cloud impacts on climate are profound – but so are uncertainties

The influence of clouds profoundly affects Earth’s radiation budget, easily overwhelming CO2’s impact within the greeenhouse effect. This has been acknowledged by scientists for decades.

Despite the magnitude of clouds’ radiative impact on climate, scientists have also pointed out that our limited capacity to observe or measure cloud effects necessarily results in massive uncertainties.

For example, Stephens et al. (2012) estimated the uncertainty in Earth’s annual longwave surface fluxes is ±9 W/m² (~18 W/m²) primarily due to the uncertainties associated with cloud longwave radiation impacts.

Settled Science? New Climate Study Shifts the Goalposts to 2.6-3.9C

by Eric Worall, July 24, 2020 in WUWT

A new climate study has dismissed utterly implausible high end climate models. But the new study also seeks to raise the low end of the range of estimated climate sensitivity into the discomfort zone.

The treatment of cloud feedback is interesting. The study acknowledges large cloud feedback uncertainties, mentions the Lindzen et al. (2001) “iris effect”, and admits GCMs cannot be trusted to reproduce observed cloud response, yet still appears to attempt to derive a cloud feedback factor based on satellite observations, and mix this observational cloud factor with model predictions.

The treatment of clouds may turn out to be one of the most controversial assumptions in the study – as Pat Frank has pointed out on a number of occasions, the magnitude of model cloud response error is significantly greater than the CO2 driven warming which models attempt to project, which calls into question whether climate models have any predictive skill whatsoever.

To the author’s credit they have described their method in great detail, so I’m looking forward to detailed responses to this study.


by Cap Allon, June28, 2020 in Electroverse

A June, 2019 research paper concludes that human activity can account for no more than a 0.01C rise in global temperatures, and goes so far as to “prove” low-level clouds “practically control the global temperature”.

The paper, entitled No Experimental Evidence for the Significant Anthropogenic Climate Change and published in Nature, is the work of a group Finnish scientists. It explains how the IPCC’s analysis of global temperatures suffers from at least one glaring error — namely, the failure to account for “influences of low cloud cover” on global temperatures.


In this paper we will prove that GCM-models used in IPCC report AR5 fail to calculate the influences of the low cloud cover changes on the global temperature. That is why those models give a very small natural temperature change leaving a very large change for the contribution of the green house gases in the observed temperature. This is the reason why IPCC has to use a very large sensitivity to compensate a too small natural component. Further they have to leave out the strong negative feedback due to the clouds in order to magnify the sensitivity. In addition, this paper proves that the changes in the low cloud cover fraction practically control the global temperature.

For the full paper, click here.


New Studies Show Cloud Cover Changes Have Driven Greenland Warming And Ice Melt Trends Since The 1990s

by K. Richard, April 20, 2020 in NoTricksZone

Scientists now acknowledge cloud cover changes “control the Earth’s hydrological cycle”, “regulate the Earth’s climate”, and “dominate the melt signal” for the Greenland ice sheet via modulation of absorbed shortwave radiation.  CO2 goes unmentioned as a contributing factor.



Ships’ emissions create measurable regional change in clouds

by  University of Washington, March 24, 2020 in ScienceDaily

A container ship leaves a trail of white clouds in its wake that can linger in the air for hours. This puffy line is not just exhaust from the engine, but a change in the clouds that’s caused by small airborne particles of pollution.

New research led by the University of Washington is the first to measure this phenomenon’s effect over years and at a regional scale. Satellite data over a shipping lane in the south Atlantic show that the ships modify clouds to block an additional 2 Watts of solar energy, on average, from reaching each square meter of ocean surface near the shipping lane.

The result implies that globally, cloud changes caused by particles from all forms of industrial pollution block 1 Watt of solar energy per square meter of Earth’s surface, masking almost a third of the present-day warming from greenhouse gases. The open-access study was published March 24 in AGU Advances, a journal of the American Geophysical Union.

New Study Asserts Cloud Cover Changes Drove The Post-1980s Solar Radiation Increase Important To Recent Warming

by K. Richard, March 2, 2020 in NoTricksZone

Using NASA’s MERRA-2 radiation data, scientists find shortwave radiation (SW) has been rising since the 1980s. The SW increase has been larger and faster than longwave radiation (LW) changes during this same timespan. Cloud variability has been the “main driver” of these trends.

In a new Nature journal paper (Delgado-Bonal et al, 2020) published in Scientific Reports, scientists use radiation records from NASA to conclude shortwave (SW) changes are “mainly determined” by cloud modulation.

Clouds are “showing a declining trend” from 1984-2014. Fewer clouds means less SW radiation is reflected to space and more is absorbed by the Earth’s surface.

Finally! The missing link between exploding stars, clouds and climate on Earth

by Shaviv, December  19, 2017 in ScieneBits/fromNature

By Henrik Svensmark and Nir shaviv

Our new results published today in nature communications provide the last piece of a long studied puzzle. We finally found the actual physical mechanism linking between atmospheric ionization and the formation of cloud condensation nuclei. Thus, we now understand the complete physical picture linking solar activity and our galactic environment (which govern the flux of cosmic rays ionizing the atmosphere) to climate here on Earth though changes in the cloud characteristics. In short, as small aerosols grow to become cloud condensation nuclei, they grow faster under higher background ionization rates. Consequently, they have a higher chance of surviving the growth without being eaten by larger aerosols. This effect was calculated theoretically and measured in a specially designed experiment conducted at the Danish Space Research Institute at the Danish Technical University, together with our colleagues Martin Andreas Bødker Enghoff and Jacob Svensmark.


It has long been known that solar variations appear to have a large effect on climate. This was already suggested by William Herschel over 200 years ago. Over the past several decades, more empirical evidence have unequivocally demonstrated the existence of such a link, as exemplified in the examples in the box below.

NASA: We Can’t Model Clouds, So Climate Model Projections Are 100x Less Accurate

by K. Richard, August 30, 2019 in ClimateChangeDispatch

NASA has conceded that climate models lack the precision required to make climate projections due to the inability to accurately model clouds.

Clouds have the capacity to dramatically influence climate changes in both radiative longwave (the “greenhouse effect”) and shortwave.

Cloud cover domination in longwave radiation

In the longwave, clouds thoroughly dwarf the CO2 climate influence. According to Wong and Minnett (2018):

  • The signal in incoming longwave is 200 W/m² for clouds over the course of hours. The signal amounts to 3.7 W/m² for doubled CO2 (560 ppm) after hundreds of years.

  • At the ocean surface, clouds generate a radiative signal 8 times greater than tripled CO2 (1120 ppm).

  • The absorbed surface radiation for clouds is ~9 W/m². It’s only 0.5 W/m² for tripled CO2 (1120 ppm).

  • CO2 can only have an effect on the first 0.01 mm of the ocean. Cloud longwave forcing penetrates 9 times deeper, about 0.09 mm.


Greenland ice loss projections are clouded by clouds

by Brooks Hays, June 24, 2019 in UPI

June 24 (UPI) — Predicting where, how and how quickly Greenland’s ice will melt is difficult. Projections by the best models are cloudy, and new research suggests clouds are doing the clouding.

Currently, models of Greenland’s melting ice sheet put the greatest emphasis on the impacts of greenhouse gas emissions. But new research, published this week in the journal Nature Climate Change, suggests the microphysics of clouds are equally important.


Under high emission scenarios, the uncertainties of Greenland ice sheet models are caused almost entirely by the uncertainties of cloud dynamics.

Cloud cover dictates the ice sheet’s longwave radiation exposure. When clouds over Greenland are thicker, they operate like an insulating blanket, encouraging longwave radiation and surface-level melting.

Scientists: The CO2 Greenhouse Effect Was Cancelled Out By Clouds During 1992-2014

by K. Richard, March 28, 2019 in NoTricksZone

An unheralded but significant 2016 scientific paper – “A Hiatus of the Greenhouse Effect” – is now publicly available.

Scientists have found the greenhouse effect’s (GHE) influence on planetary temperatures went on “hiatus” during 1992-2014.

The estimated GHE radiative influence for these 22 years was a slightly negative -0.04 Wm-2 per year.

The reason why the GHE influence went on hiatus in recent decades is that (a) decadal-scale changes in cloud cover exert dominant radiative control in longwave forcing (GHE) efficacy, and (b) the shortwave effects of cloud cover changes override the radiative longwave effects, meaning that a decrease in cloud cover will allow more direct shortwave radiation to be absorbed by the Earth system, eliciting a net positive imbalance in the energy budget.


L’art de gommer les incertitudes

by Jean, N. 2 mars 5019 in ScienceClimatEnergie

Comme déjà mentionné dans un article précédent publié sur SCE, la variation de la couverture nuageuse a probablement un effet majeur sur la température moyenne globale de la basse atmosphère. Si l’on veut prédire le climat du futur comme le prétend le GIEC il faut savoir modéliser la formation des nuages. Que nous dit le dernier rapport scientifique (AR5) du GIEC à ce sujet? Le but du présent article est simplement de vous présenter quelques phrases tirées de ce rapport. La science est-elle dite?

1. Le chapitre 7 du rapport AR5 publié par le GIEC en 2013

Le chapitre 7 du rapport AR5 du GIEC[1] fait 60 pages et est consacré aux nuages et aux aérosols (le rapport AR5 complet fait au total 1535 pages). Ce chapitre 7 comporte 22 pages de références et cite plus de 1100 articles scientifiques publiés dans des revues aussi prestigieuses que Science, Nature ou PNAS. Le chapitre 7 a été écrit sous la direction de Olivier Boucher (France) et David Randall (USA), deux spécialistes du domaine. Nous n’allons pas ici remettre en question la validité de ce chapitre. Nous allons simplement vous présenter quelques phrases tirées du rapport. Comme le rapport est écrit en anglais nous vous proposerons ci-dessous une “traduction maison” des phrases qui nous paraissent les plus importantes, assorties parfois de quelques explications pour bien les comprendre. Les lettres entre crochets ([A] à [P]) renvoient simplement au texte original en anglais, donné en Annexe du présent article.

Striking study finds a climate tipping point in clouds

by Scott K. Johnson, February 25, 2019 in WUWT

The word “hysteresis” doesn’t immediately seem threatening; it hints at a portmanteau of “history” and “thesis”—a dense read, perhaps, but those never killed anyone. But that’s not what the word means. Hysteresis is a profound behavior some systems can display, crossing a sort of point-of-no-return. Dial things up just one notch, and you can push the system through a radical change. To get back to normal, you might have to dial it down five or six notches.

Earth’s climate system can provide examples. Take the conveyor-belt-like circulation of water in the Atlantic Ocean. Looking back at the past, you can see times that the circulation seems to have flipped into an alternate pattern regarding climatic consequences around the North Atlantic. Switching from one pattern to the other takes a significant nudge, but reversing it is hard—like driving up to the top of a ridge and rolling down into the next valley.

Stratocumulus clouds, like those in the lower two-thirds of this image, are common over the oceans.

NASA Earth Observatory

Aerosol-driven droplet concentrations dominate coverage and water of oceanic low-level clouds

by  D. Rosenfeld et al., February 8, 2019 in Science

Reflections on cloud effects

How much impact does the abundance of cloud condensation nuclei (CCN) aerosols above the oceans have on global temperatures? Rosenfeld et al.analyzed how CCN affect the properties of marine stratocumulus clouds, which reflect much of the solar radiation received by Earth back to space (see the Perspective by Sato and Suzuki). The CCN abundance explained most of the variability in the radiative cooling. Thus, the magnitude of radiative forcing provided by these clouds is much more sensitive to the presence of CCN than current models indicate, which suggests the existence of other compensating warming effects.

German Scientists To More Closely Investigate Cloud Formation, A Vital Component In Climate

by P. Gosselin, January 27, 2019 in NoTricksZone

Leipzig, 20 December 2018

Researchers from Leipzig cooperate with scientists from Punta Arenas (Chile) to learn more about the relationship between air pollution, clouds and precipitation.

Leipzig/Punta Arenas. How do airborne particles, so-called aerosols, affect the formation and life cycle of clouds and precipitation? In order to come one step closer to solving this question, atmospheric scientists from the Leibniz Institute for Tropospheric Research (TROPOS) and the Leipzig Institute for Meteorology (LIM) at Leipzig University will observe the atmosphere at one of the cleanest places in the world for at least a year. The choice fell on Punta Arenas because the city is located on a comparable geographical latitude as Germany and will thus enable comparisons between the northern and southern hemispheres. The measurement campaign is part of the International Year of Polar Prediction (YOPP), which aims to improve weather and climate forecasts for the polar regions through intensive measurements.

Study: Climate models underestimate cooling effect of daily cloud cycle

by Princeton University, January 10, 2018 in WUWT

Princeton University researchers have found that the climate models scientists use to project future conditions on our planet underestimate the cooling effect that clouds have on a daily — and even hourly — basis, particularly over land.

The researchers report in the journal Nature Communications Dec. 22 that models tend to factor in too much of the sun’s daily heat, which results in warmer, drier conditions than might actually occur. The researchers found that inaccuracies in accounting for the diurnal, or daily, cloud cycle did not seem to invalidate climate projections, but they did increase the margin of error for a crucial tool scientists use to understand how climate change will affect us.

Study: Climate models underestimate cooling effect of daily cloud cycle

by Princeton University, January 10, 2018 in A. Watts WUWT

Princeton University researchers have found that the climate models scientists use to project future conditions on our planet underestimate the cooling effect that clouds have on a daily — and even hourly — basis, particularly over land.

The researchers report in the journal Nature Communications Dec. 22 that models tend to factor in too much of the sun’s daily heat, which results in warmer, drier conditions than might actually occur. The researchers found that inaccuracies in accounting for the diurnal, or daily, cloud cycle did not seem to invalidate climate projections, but they did increase the margin of error for a crucial tool scientists use to understand how climate change will affect us.

Where The Temperature Rules The Total Surface Absorption

by Willis Eschenbach, December 22, 2017 in WUWT

Reflecting upon my previous post, Where The Temperature Rules The Sun, I realized that while it was valid, it was just about temperature controlling downwelling solar energy via cloud variations. However, it didn’t cover total energy input to the surface. The total energy absorbed by the surface is the sum of the net solar energy (surface downwelling solar minus surface reflections) plus the downwelling longwave infrared, or DWIR. This is the total energy that is absorbed by and actually heats the surface.

Is The Average Variation Of Clouds CO2?

by E.M. Smith, June 26, 2017

Until cloud and precipitation data are adequate AND accounted for properly AND the error bands are low enough to cover 1/10 degree increments, we can’t say there is ANY effect from CO2 on temperature. It is at most a conjecture, and not a very good one. You can not ignore the major driver of changes of temperatures (as shown in the above graph) and then attribute temperature changes to something else by supposition.