CERN CLOUD experiment pushes forward with new partners and imminent papers within AR5 deadline

Posted: April 26, 2012 by tallbloke in Astrophysics, atmosphere, climate, cosmic rays, Electro-magnetism, Energy, general circulation, Ocean dynamics, solar system dynamics, weather

CLOUD Collaboration

The first physics results from CLOUD [1] were published in Nature, August 2011 [2]. The measurements
represent the most rigorous laboratory evaluation yet accomplished of binary, ternary and ion-induced
nucleation of sulphuric acid/ammonia aerosol particles under atmospheric conditions. Several new findings
were reported. Firstly, CLOUD has shown that the most likely nucleating vapours, sulphuric acid
and ammonia, cannot account for nucleation in the lower atmosphere. The nucleation observed in the
chamber occurs at only one-tenth to one-thousandth of the rate observed in the lower atmosphere (Fig. 1).
In view of the CLOUD results, the treatment of aerosol formation in climate models will need to be substantially
revised since all models assume that nucleation is caused by these vapours and water alone.
Secondly, CLOUD has found that cosmic ray ionisation can substantially enhance nucleation of sulphuric
acid/ammonia particles—by up to a factor of 10. Ion-enhancement is particularly pronounced in
the cool temperatures of the mid-troposphere and above, where CLOUD has found that sulphuric acid
and water vapour can nucleate without the need for additional vapours.

The publication of the first CLOUD results in Nature [2] attracted wide interest in the media and scientific
press, including articles in The Economist [3],Wall Street Journal, CERN Courier [4], Nature News, and
Nature Geoscience [5]. The results were also reported at numerous scientific meetings, including an
invited plenary talk at the European Aerosol Conference, EAC2011, Manchester, September 2011.
The CLOUD4 and CLOUD5 runs in 2011 have revealed a number of important new findings
which are currently being analysed. Several high profile (Nature/Science) manuscripts are in preparation.
At least two of these will be submitted for publication before 31 July 2012. This date marks the
submission deadline for papers to be eligible for inclusion in the 5th Assessment Report (AR5) of the
Intergovernmental Panel on Climate Change (IPCC), which is due to be completed by the end of 2013.
For the first time, a chapter in AR5 will be devoted to “Clouds and Aerosols”, and it will contain a section
on the influence of galactic cosmic rays.
In addition to the high profile manuscripts, a further 20 papers are in preparation for submission
to Atmospheric Chemistry and Physics, an open access—and highly popular—Journal of the European
Geosciences Union. Several papers have already been published [6, 7, 8, 9] and about ten more are
expected to be submitted by mid 2012. Fourteen CLOUD abstracts have been submitted to the European
Aerosol Conference, EAC2012, Granada, September 2012.

Several new partners joined CLOUD during 2011, with special expertise as indicated:
Karlsruhe Institute of Technology, Germany: laboratory measurements of aerosols, liquid- and ice
clouds (AIDA facility).
University of Stockholm, Sweden: atmospheric aerosol growth from organic vapours.
Carnegie Mellon University, USA: atmospheric organic chemistry and aerosol growth.
The Memorandum of Understanding for the maintenance and operation of CLOUD has been finalised
and signed by the CERN Director for Research and Computing. It is currently being signed by
the 19 CLOUD partners (U Innsbruck, U Vienna, U Helsinki, Finnish Meteorological Institute, U Eastern
Finland, U Frankfurt, Karslruhe Institute of Technology, Institute for Tropospheric Research – Leipzig,
U Lisbon, Lebedev Physical Institute – Moscow, U Stockholm, CERN, PSI, U Leeds, U Manchester,
Caltech, Carnegie Mellon, Aerodyne Research – Billerica and TOFWERK – Thun).
During 2011, CLOUD Collaboration meetings and data workshops were held at the University of
Vienna, 14–18 February and Goethe University of Frankfurt, 25–30 September.

The beam requests and experimental aims for 2012 are as follows:
CLOUD6: 4 June – 2 July 2012 (4 weeks): Commissioning of the adiabatic expansion system to
operate CLOUD in a classical Wilson expansion chamber mode for generation of liquid and ice clouds.
Instruments will be attached to CLOUD to measure, for the first time, the formation of liquid droplets
and ice particles inside the chamber. The purpose of this run is to prepare for future studies of the so
called “near-cloud” mechanism by which cosmic rays may directly influence cloud microphysics rather
than through the production of cloud condensation nuclei (Fig. 3) [10]. Three spills per supercycle are
CLOUD7: 1 October – 3 December 2012 (9 weeks): Ion-induced and neutral nucleation and growth
of sulphuric acid particles in the presence of oxidised organic vapours from pinanediol and alpha-pinene
(Fig. 4). This represents a follow-up investigation of the new processes discovered during the CLOUD4
run, and a new study of aerosol growth up to the size of cloud condensation nuclei (CCN). Three spills
per supercycle are requested.

CLOUD (Fig. 5) is tackling one of the most challenging problems in atmospheric science—to understand
how new aerosol particles are formed and grow in the atmosphere, and the effect these particles have on
the global atmosphere and climate. CLOUD also aims to answer definitively the question of whether or
not galactic cosmic rays affect clouds and climate, either by affecting aerosols or by directly influencing
the microphysics of liquid or ice clouds. The contribution of aerosols and clouds is recognised by the
Intergovernmental Panel on Climate Change as the most important source of uncertainty in the radiative
forcing of climate change.
The present poor experimental understanding of aerosol nucleation and growth is preventing the
inclusion of physics-based mechanisms in global models, and limiting our understanding of how a major
fraction of atmospheric aerosol will influence future climate. Development of reliable atmospheric models
requires quantifying the fundamental physics and chemistry of nucleation in the laboratory, as well
as a clear connection between the laboratory and the real world through these models.
In the near-term, the 2012 scientific goals for CLOUD are well-defined. During the 2013 shutdown
of the CERN accelerators for the LHC energy upgrade, the CLOUD collaboration will likely devote a
major effort into analysis of the large quantity of high quality data already collected during the last 3
years. Nevertheless, depending on the results obtained later in 2012, it is likely that CLOUD will operate
at some stage during 2013 for special physics measurements that do not require a particle beam. We
expect to begin normal data-taking operations for CLOUD when the PS beams return in 2014. The
precise physics programme cannot be defined at this stage since it will depend on our findings during

For the first time we have with the CLOUD facility at CERN an experimental chamber of the highest
technological performance which has established itself as the world’s leading experiment for these
studies. CLOUD has also brought together a world-class team of atmospheric and modeling experts to
conduct the experiments, analyse and interpret the data, and assess the impact of the results with global
models. Nevertheless, a multi-parameter experimental phase space must be mapped, involving numerous
variables such as temperature, relative humidity, trace gases and their concentrations, ionisation, nucleation
rates, growth rates, droplet and ice particle activation, as well as liquid and ice cloud microphysics.
CLOUD has been in operation for just over two years and we estimate around ten more years will be
required to carry out the experimental programme.
The projected CLOUD experimental programme is therefore likely to extend well beyond the
planned upgrade of the East Hall beamlines. After several year’s experience in the T11 beamline we
would like to request that T11 be retained for CLOUD in the new East Hall beamline layout, ideally with
1–2 m additional space in the experimental zone in the direction towards T10. A dedicated T11 beamline
for CLOUD will maximise the efficiency and output of the experiment, and provide the maximum
availability of the T9 and T10 beamlines for test-beam users.

We would like to thank CERN PH-DT, EN-MME, EN-MEF and TE-VSC for their excellent support of
CLOUD and, in addition, to thank the CERN PS machine team and the PS Coordinator for their strong
support of CLOUD and for efficient operation of the PS.

[1] CLOUD Collaboration: A study of the link between cosmic rays and clouds with a cloud chamber
at the CERN PS.
CERN-SPSC-2000-021 (2000), <;
CERN-SPSC-2000-030 (2000), <;
CERN-SPSC-2000-041 (2000), <;
CERN-SPSC-2006-004 (2006). <;
[2] Kirkby, J., et al. Role of sulphuric acid, ammonia and galactic cosmic rays in atmospheric aerosol
nucleation. Nature 476, 429–433 (2011).
[3] The Economist. Clouds in a jar; a new experiment with old apparatus reveals a flaw in models of
the climate (27 August 2011). <;
[4] Kirkby, J. CLOUD: closing in on the initial steps of cloud formation. CERN Courier 51, 8, 28–31
(October 2011). <;
[5] Pierce, J. Particulars of particle formation. Nature Geoscience 4, 665–666 (2011).
[6] Kupc, A., et al.. A fibre-optic UV system for H2SO4 production in aerosol chambers causing
minimal thermal effects. J. Aerosol Sci. 42, 8, 532–543 (2011).
[7] Voigtl¨ander, J., Duplissy, J., & Stratmann, F. Numerical simulation of flow, H2SO4 cycle and new
particle formation in the CERN CLOUD chamber. Atmos. Chem. Phys. Discuss. 11, 20013–20049
[8] Bianchi, F., Dommen, J., Mathot, S., & Baltensperger, U. On-line determination of ammonia at low
pptv mixing ratios in the CLOUD chamber. Atmos. Chem. Phys. Discuss. 5, 2111–2130 (2012).
[9] Praplan, A.P., Bianchi, F., Dommen, J., & Baltensperger, U. Dimethylamine and ammonia measurements
with ion chromatography during the CLOUD4 campaign. Atmos. Chem. Phys. Discuss.
5, 2395–2413 (2012).
[10] Carslaw, K.S., Harrison, R.G., & Kirkby, J. Cosmic rays, clouds, and climate. Science 298, 1732–
1737 (2002).

Full pdf here.

  1. adolfogiurfa says:

    It would be interesting to have a chamber filled with O2/O3 and watch the formation of new water molecules by the bombardment of protons.

  2. Ray C says:

    Thanks Tallbloke, for posting this important stuff. I hope people take ‘on-board’ how important secondary aerosol formation really is, and the role all aerosol have on climate formation for that matter. Good stuff, some important findings in the near future me thinks!
    CLOUD has found that cosmic ray ionisation can substantially enhance nucleation of sulphuric acid H2SO4 /ammonia “salt of Ammon” NH3 particles -by up to a factor of 10.
    Atmospheric physics is notoriously complex. It is good to see the realisation that a closer look is needed into what is going on in the real atmosphere.

  3. James says:

    It’s an odd thing but there was not a breath of wind today and there was blue sky to be seen in all directions and just light grey clouds overhead, yet it pissed down with a vengeance all day. There is more to this water from the sky than we realise.

  4. B_Happy says:

    If the nucleation rate in the Cloud chamber is 1000 times smaller than in nature then either
    a) the Cloud results are wrong
    b) there is some physics missing.

    If cosmic rays increase the rate by up to ten, then it is still a factor of 100 too small, so
    a) either the theory is wrong
    b) there is some physics missing.

    I would vote for b) in both cases.

  5. diogenes says:

    wow! real experimental climate stuff….the physics labs cannot even demonstrate the greenhouse effect so we have to rely on CERN to do the basics.

  6. Tenuc says:

    Always surprised me that climate models didn’t include the effect of water droplet formation from ionising radiation. The Wilson cloud chamber was invented back in 1911 for this very purpose, after Charles Wilson was inspired by observing a Mountain Glory on Ben Nevis.

    I would be very surprised if the next series of CLOUD experiments did not confirm the production of droplets. Seems climatology conveniently forgot about some basic physics and is now going to get its noses rubbed in it… 🙂

  7. Ray C says:

    The following two links come from the WUWT Potential Climatic Variables Page
    Compiled by WUWT regular “Just The Facts”

    “Aerosols play a critical role in the formation of clouds;

    Clouds form as parcels of air cool and the water vapor in them condenses, forming small liquid droplets of water. However, under normal circumstances, these droplets form only where there is some “disturbance” in the otherwise “pure” air. In general, aerosol particles provide this “disturbance”. The particles around which cloud droplets coalesce are called cloud condensation nuclei (CCN) or sometimes “cloud seeds”. Amazingly, in the absence of CCN, air containing water vapor needs to be “supersaturated” to a humidity of about 400% before droplets spontaneously form! So, in almost all circumstances, aerosols play a vital role in the formation of clouds.”

    I need to get things straight with the whole issue of Aerosol and the role they play in our climate. You see! I see the word “Amazingly”…As though the process is something so extraordinary as to be barely believable or to cause extreme surprise.
    It is a fundamental reality of cloud microphysics that water vapour will preferentially condense onto aerosol because there are so many of them, (vapour is sure to find a suitable surface) why would vapour try to supersaturate to form droplets if there is an easier way! Only when the cloud has formed droplets on aerosol in the first instance do saturation levels rise. Then all the other wet deposition processes take place.

    This just demonstrates how necessary aerosol are to the whole process of cloud formation. The air is full of a constant, albeit variable, supply of solid and liquid material onto which water vapour preferentially condenses.
    The CGR ionisation process is not the full story!

  8. Ray C says:

    This suggests that the most prolific aerosol, dust ( or on a par with salt aerosol) is not represented correctly. They are giving dust aerosol too much cooling potential. GCMs will never be a good guesstimate until this is put right!

    A scaling theory for the size distribution of emitted dust aerosols suggests climate models underestimate the size of the global dust cycle

    Click to access kok2011_pnas_scalingtheorydustpsd.pdf

    Because clay aerosols produce a strong radiative cooling, the overestimation of the clay fraction causes GCMs to also overestimate the radiative cooling of a given quantity of emitted dust.
    On a global scale, the dust cycle in most GCMs is tuned to match radiative measurements, such that the overestimation of the radiative cooling of a given quantity of emitted dust has likely caused GCMs to underestimate the global dust emission rate. This implies that the deposition flux of dust and its fertilizing effects on ecosystems may be substantially larger than thought.
    This latter result implies that the deposition flux of dust to oceans, and the resulting effect on atmospheric green-house gas concentrations through the fertilization of marine biota may be substantially larger than previously thought, especially close to dust source regions.

  9. Ray C says:

    Dust aerosol from land surface and volcanic eruptions create a lot of deposition of Iron.
    All organisms on Earth ride upon a “ferrous wheel” made of different forms of iron that are essential for life.
    As a result, large volcanic eruptions could lead to a significant increase in the primary production of organisms that inhabit Earth’s oceans. This, in turn, could lead to a cooler planet as more CO2 (a greenhouse gas) is removed from Earth’s atmosphere and sequestered in the biomass of these ocean-dwelling photosynthetic organisms. The result is a tantalizing negative relationship between iron in dust particles, and CO2 levels in different layers of Antarctic ice cores that span several ice ages. The connection was developed into the “Iron Hypothesis” by oceanographer John Martin, who summarized the importance of Fe to Earth’s oceans and hence Earth’s climate with the provocative claim, “Give me a half a tanker of iron and I’ll give you the next ice age.”

    If GCRs start a process of cooling through cloudiness and this causes an increase in wind speed the knock-on effect is more aerosol production, cooling and ocean fertilisation. Natural carbon storage.

  10. tallbloke says:

    Hi Ray C: thanks for the useful links and thoughts. As I understand it, dust is a lot rarer over the oceans, which cover 70% of the Earth. You would expect that this is where the Svensmark effect would predominate. Of course, there are as you say other sources of aerosols which seed CCN’s.

    Circumstantial evidence for a Svensmark effect is starting to look stronger in my view. The heat wave in March followed the forbush decrease caused by strong solar flare activity. Clouds were reduced not only over the ocean but over land too. Is there a direct effect on ionisation by solar activity interacting with the atmosphere?

  11. Joe Lalonde says:

    Thanks TB!
    Your presentations really help me in understanding what scientists have left out when drawing conclusions to their experiments.

    Velocity and motion are certainly NOT in consideration.
    I just realized that I should be able to have a velocity of our planets orbit around the sun as well as the velocity of our atmosphere. All the calculating parameters are in place that I should be able to calculate our solar systems orbits.
    It will beg to differ if we are traveling trough cosmic rays or as current science looks at it are stationary being bombarded by them.

  12. edcaryl says:

    If cosmic rays contribute to aerosols then there should be a relationship, but there isn’t.

  13. tallbloke says:

    Hi Ed: I read that article and the previous one linked from it. Nice clear presentations, thanks.
    It seems to me that there are electromagnetic effects to be considered. Ionisation of the atmosphere is affected by solar events acting on the magnetosphere and this in turn affects the effectiveness of aerosols in performing as cloud condensation nuclei.

    Brian Tinsley has done a lot of interesting work on this.

    I wonder if high GCR count and low solar activity have incompletely cancelling effects.

    Have you looked at any of Doug Hoyt’s work on pyrheliometry? He found transmission hadn’t changed appreciably over a 70 year period at Davos Switzerland.

    The Forbush decreases associated with solar flares and geomagnetiic substorms do seem to have effects on cloud cover, the heatwave in March being a recent example. The UK’s geomagnetic storm monitoring service shows a general increase over the C20th, along with a recent drop. This seems to match sunshine hours counts quite well. And the sunshine hours counts seem to match temperature records well too.

    Food for thought I hope.

  14. tallbloke says:

    Ed, further thought: Svensmark says in his new paper that ” A high flux of GCR results in an increase in the number of cloud condensation nuclei which in turn increases the albedo of the clouds.”

    Your article says:
    “The transmission is measured in a clear-sky situation. Albedo reflection is mostly from clouds. If aerosols impede transmission and aerosols ultimately produce clouds, then there should be a relationship.”

    So, what is the evidence that aerosols of the type generated by GCR’s do indeed impede transmission “in a clear-sky situation”?

  15. diogenes says:

    over on Bishop Hill, people have been asking for lab notes or demos of experiments that show the 2 disc radiation model

    Reader Jorge describes a test rig, but it needs pro resources. Reader Bownedoff wonders if it is a staple experiment in climate science degrees.

    Most of us woncer whether the experiment has ever been conducted.The accounts of Arrhenius (saint or fascist) are equivocal on this matter.

  16. Ed Caryl says:

    “So, what is the evidence that aerosols of the type generated by GCR’s do indeed impede transmission “in a clear-sky situation”?”
    Good question. Hard to find an answer. Svensmark says the particles grow by accretion over a few days. So there should be a wide range of sizes from sub micron molecular size up to micro droplets. I found a paper here:

    Click to access AerosolRadiativeForcing.pdf

    That seems to indicate that the smaller particles scatter light (in all directions) more than larger ones, so size is not the issue. It seems that most of the impedance is due to scattering, including upscatter, whitch adds to albedo.

  17. tallbloke says:

    Hi Ed,
    Thanks for that. I wonder if you would find a signal if you restricted the study to the higher latitudes where more GCR’s get into the lower atmosphere. The paper Leif likes to quote (can’t find the reference at the moment) admits there is a much bigger Svensmark effect north of 40 degrees.

    Svensmark himself says in the new paper that solar activity modulates the incidence of GCR’s by around 10%. This maybe enough to make a significant difference to low cloud cover without affecting albedo very much over the solar cycle.

    Nir Shaviv found an amplification to the solar variation of between 7-10 times in his JGR paper summarized here:

  18. Joe Lalonde says:


    Do you believe in coincidences?
    As you go deeper in the ocean, it gets heavier and has more pressure.
    It also has less and less planetary velocity.

    Who’d a thunk?

  19. Ed Caryl says:

    In the arctic the signal is obscured by seasonal variation (mostly soot) and a steady increase in absorbance. The individual stations have too much local turbidity production.

  20. Brian H says:

    adolfogiurfa says:
    April 26, 2012 at 4:55 pm

    It would be interesting to have a chamber filled with O2/O3 and watch the formation of new water molecules by the bombardment of protons.

    Indeed! Anent which, the EU people attribute the anomalous observations of H2O plumes from comets to proton-oxygen combination, as opposed to the canonic “dirty snowball” outgassing assumptions.