Why the science of clouds is still cloudy

Posted: March 4, 2016 by oldbrew in Clouds, modelling
Tags: ,

Cloud formation [image credit:NASA]

Cloud formation [image credit:NASA]


This extract from a Phys.org article looks at some of the difficulties climate models have with clouds, a subject the Talkshop featured recently. One scientist says: ‘A key problem is that we generally do not have data on clouds from the pre-industrial era, before there was pollution, for comparison with the clouds of today.’ Another good reason to use more caution over possible future climate trends, perhaps?

Cloudy complexity

Currently, when scientists use models to calculate the extent to which aerosols—through clouds—affect the earth’s climate, they get a much, much wider range and greater uncertainty than for greenhouse gases. Why?

Clouds are complex—their properties are influenced by tiny aerosol particles called cloud condensation nuclei that cloud droplets form around; a greater number of particles leads to more cloud droplets which in turn affects the cloud brightness and lifetime, since small cloud droplets hang around for hours, and larger water droplets are more prone to come down as rain, if they’re heavy enough. The physics and chemistry underlying these and other components mean scientists have to represent daunting complexity in models.

Also, clouds are ephemeral creatures. The measurements of clouds that scientists now take have no counterpart in the geologic record, unlike greenhouse gases that are preserved in bubbles in ice cores. Between ice cores, rocks, trees, and fossils, researchers have a good idea how much carbon dioxide existed in the pre-industrial atmosphere. But they can’t tell how often dinosaurs cavorted under cloudy skies.

To see how well cloud and aerosol measurements are represented in models, Ghan and colleagues compared different models to each other and to measurements and examined how they re-created the past and present. They did this by essentially taking apart the simulations and testing the pieces.

Comparing models

A climate model is like a train barreling through a tunnel—scientists put data on the train at one end and the train delivers a view of the climate out the other. In a perfect world, the simulated climate would take a smooth ride through that tunnel. But it’s possible that a rollercoaster resides within, taking the simulation through twists and turns that don’t resemble reality.

To compare the different models, the team looked at the rides taken by the individual components of the equations that make up the simulations. The relationship between the pre-industrial and present day values of any given component, say, the changes in the concentrations of cloud droplets resulting from a change in aerosols, should be the same across the nine different computer models they tested and should be reflected in data from observations.

The team found, however, that pre- and post-industrial values didn’t agree, and in some cases the there was even a difference in sign (that is, one model yielded a positive value while another yielded a negative one).That indicated they could not model pre-industrial clouds using measurements that have been collected in a post-industrial world.”It’s very curious. With greenhouse gases, climate sensitivity doesn’t change over eight hundred thousand years. It works. Why don’t clouds?” Ghan said.

Additional research is needed to figure out why pre-industrial clouds differ from today’s clouds. But Ghan said there are several potential directions to go. One, clouds may be more complex than currently represented in models. For example, clouds could have layers that scientists haven’t accounted for in models that complicate the transfer of sunlight in and out of the system. In this case, old and present-day clouds would actually be the same, but it would mean the models are missing essential complexity needed to simulate how aerosols and clouds interact. Two, today’s clouds in regions of the world where observations are made are never as clean as they were in pre-industrial times.

“Present day variability doesn’t apply to pre-industrial times because everything’s different now that we’ve been putting greenhouse gases and pollutants in the air for so long,” said Ghan. Scientists can explore this option by studying clouds in pristine regions of the world, such as in the southern hemisphere between the latitudes of 40 and 50 degrees.

A third explanation could be that the equations used to represent the cloud-aerosol interaction aren’t quite right and need to be revisited. In the future, distinguishing between these options may help scientists shine light on cloud modeling’s cloudy history.

Full report: Study helps narrow down one reason why clouds are hard to model

Comments
  1. oldbrew says:

    “It’s not enough to have particle emissions and solar energy balance alone because a lot is going on in between,” said Ghan.

    Maybe that’s one reason why climate models always give the wrong results when compared to actual real world data. Lack of understanding forces the use of assumptions which always seem to favour warming over other options.

  2. ntesdorf says:

    The effect of clouds varies throughout the day and night, every day, and differs everywhere over the surface of the earth. The absence or presence of clouds (water vapour) has a profound effect on temperature and insolation. Without a model for this, there is precious little use in developing models for CO2 to study future climate. It is another case of putting the cart before the horse.

  3. Brett Keane says:

    Always, that feeling of watching retarded lunatics…….

  4. Graeme No.3 says:

    Work some years ago (sorry no link) showed that landscape painters included much more cloud cover in the eighteenth and early nineteenth century, and that the mid to late nineteenth century more of rising air pollution and smog.

    “With greenhouse gases, climate sensitivity doesn’t change over eight hundred thousand years. It works. Why don’t clouds?”
    Is it just possible that they are exaggerating the effect of CO2?

  5. catweazle666 says:

    “With greenhouse gases, climate sensitivity doesn’t change over eight hundred thousand years.”

    Really…

    So let us see how much progress has been made over the last couple of decades pinning down this extremely important number.

    Here are the ranges of value given by the five IPCC Assessment Reports that have been published to date.

    IPCC First assessment report 1.9°C to 5.2°C, but states “…hence the models results do not justify altering the previously accepted range of 1.5°C to 4.5°C

    IPCC Second Assessment Report 2°C to 4.5 °C

    IPCC Third Assessment Report 1.5°C to 4.5 °C

    IPCC Fourth Assessment Report 2°C to 4.5 °C

    IPCC Fifth Assessment Report 1.5°C to 4.5°C

    So, despite the expenditure of many billions of dollars on research, estimates of the low and high limits of this essential parameter have not changed in 25 years.

    The original 1.5°C to 4.5°C estimate came from the 1979 Charney report.

    http://web.atmos.ucla.edu/~brianpm/download/charney_report.pdf

    As for clouds, it is very clear that most of the time clouds in daytime reduce surface warming, but at night they reduce surface cooling, hence the sign changes twice in a 24 hour period.

    Best of luck modelling that!

  6. gymnosperm says:

    Beat me to it. “It’s very curious. With greenhouse gases, climate sensitivity doesn’t change over eight hundred thousand years.”

    How would you characterize CO2 climate sensitivity in the ice cores? Since CO2 follows temperature like a poodle on a leash, zero sensitivity.

    Hopefully Ghan is astute enough to be speaking predominantly about water. Clouds are liquid water which has very different spectral properties than water vapour. Far more transparent in the solar spectrum.

  7. Ned Nikolov says:

    A fundamental misconception exists in today’s climate science regarding the role of cloud albedos in planetary climate systems (including Earth’s). The prevailing view is that clouds constitute an independent forcing that can be tweaked until models produce a desired output. However, the reality revealed by empirical data suggests that clouds and their radiative effects (such as the atmospheric albedo) are simply an emergent property of the climate system itself… In other words, the bulk of a planetary cloud albedo is a function of the kinetic energy and various feedbacks present in the climate system… Clouds are NOT a free forcing parameter, but a tightly controlled feature of the atmosphere. This explains the observed remarkable stability of planetary cloud albedos… While true that the cloud cover can be influenced by solar magnetic activity, the resulting changes (1-3 % on Earth) are fairly small compared to the bulk of the global cloud cover (~65%). This is because negative feedbacks operating in the system keep fluctuations in the cloud albedo within a rather narrow range …

  8. tom0mason says:

    We seem to have learned so little since Joni Mitchell penned ‘Both Sides Now’ —

    Bows and flows of angel hair and ice cream castles in the air
    And feather canyons everywhere, I’ve looked at clouds that way
    But now they only block the sun they rain and snow on everyone
    So many things I would have done, but clouds got in my way

    I’ve looked at clouds from both sides now
    From up and down and still somehow
    It’s cloud’s illusions I recall
    I really don’t know clouds at all

    Should this song be the UN-IPCC anthem?

  9. oldbrew says:

    catweazle: ‘As for clouds, it is very clear that most of the time clouds in daytime reduce surface warming, but at night they reduce surface cooling, hence the sign changes twice in a 24 hour period.’

    Yes, and that 24 hour period only relates to whichever part of the Earth you’re studying at the time.

    tom0: ‘I really don’t know clouds at all – Should this song be the UN-IPCC anthem?’

    If the cap fits…😉

  10. AlecM says:

    The real issue is that the Sagan-Pollock albedo-optical depth model, adapted by Lacis and Hansen in 1974 and which is at the core of the climate models, is plain wrong, hence Sagan’s many claims about nuclear winter and Saddam burning the oil wells, were way off target.

    The root cause is in the experiments of van de Hurst in the 1950s: his sons sols had a wide droplet size distribution and rte S-P model applies solely to that r-dispersion! More later…..

    Perhaps the worst effect of this mistake is that ‘positive feedback’ in the GCMs is a modelling artefact!

  11. AlecM says:

    Sorry, not van de Hulst’s sons! Should be ‘sols’ – he probably used milk.

  12. oldbrew says:

    Reminder of CERN’s results:
    ‘This is a very important result, since it identifies a key ingredient responsible for formation of new aerosol particles over a large part of the atmosphere – and aerosols and their impact on clouds have been identified by the Intergovernmental Panel on Climate Change as the largest source of uncertainty in current climate models.’
    Jasper Kirkby, CLOUD experiment
    http://home.cern/about/updates/2014/05/cern-experiment-sheds-new-light-cloud-formation

  13. E.M.Smith says:

    They say there is no pre industrial cloud data, then say they test different aproaches to see which correctly model pre industrial clouds. How would they know with no data?

  14. ren says:

    The Arctic in Europe.

  15. oldbrew says:

    @ EM Smith – they mean their pre-industrial models were used for comparison AFAIK.

    ‘To compare the different models, the team looked at the rides taken by the individual components of the equations that make up the simulations.’

  16. ren says:

    Another wave of GCR.

  17. oldbrew says:

    This looks relevant to cloud theory.

    Graphic came from here (I haven’t read it all yet). Doesn’t mention ozone.
    http://climatescienceskeptic.blogspot.co.uk/2008/02/new-theory-of-climate-change-its-even.html

    The writer seems to assume cosmic rays are a force in their own right, but they could just (or also) be an indicator of something else e.g. solar wind strength.

  18. Paul Vaughan says:

    Remember that as equator-pole gradients change over the course of the solar cycle the shape and flow of the atmosphere changes. Neutron count rate (an indicator of GCR flux) varies with the shape changes. (I keep seeing data misinterpretations, so I note this again.)

  19. Brett Keane says:

    @Ned Nikolov says:
    March 5, 2016 at 6:04 am: Thanks, Ned, that is what I’ve wondered about since we discussed the revelatory data for Venus and other bodies, wiping out AGW. Then I could sense that it was also telling us news about albedo, in that it seemed a two-way energy flow,mainly internal, and complex at that. I also suspect that translucent solids could complicate things further, as shown by Konrad Hartmann.

    As for clouds and AGW models etc., what a bunch of pretenders.

  20. ren says:

    There will be plenty of cold in the Atlantic.

  21. ren says:

    You have to see how rapid a rise in temperature in the stratosphere after wave of GCR in January. The initial temperature is well below average.

  22. Paul Vaughan says:

    Ned Nikolov (March 5, 2016 at 6:04 am) wrote:

    “The prevailing view is that clouds constitute an independent forcing […] the reality revealed by empirical data suggests that clouds and their radiative effects (such as the atmospheric albedo) are simply an emergent property of the climate system itself… In other words, the bulk of a planetary cloud albedo is a function of the kinetic energy and various feedbacks present in the climate system… Clouds are NOT a free forcing parameter, but a tightly controlled feature of the atmosphere. This explains the observed remarkable stability of planetary cloud albedos… […] negative feedbacks operating in the system keep fluctuations in the cloud albedo within a rather narrow range …” (bold added)

    The notion that clouds are an independent forcing is crazy.
    They’re coupled to everything!

    Kinetic energy — now THAT makes sense.

    I can’t remember ever seeing anyone make such a sensible suggestion about clouds that’s consistent with observation no less!

    What I’ve mostly seen over the years is a lot of crazy conjecture about clouds that makes no sense at all and is totally inconsistent with the data, to the point where I’ve actually tuned out cloud discussion.

    But finally a comment with simple clarity consistent with observation…

    What do people have against kinetic energy??

    To deliberately provoke thinking more aligned with observation I’ll tell you what it’s not: It’s not GCRs. (See my comment above (March 5, 2016 at 7:29 pm).

    Kinetic energy — now there’s a breath of fresh air. About ****ing time!

  23. Paul Vaughan says:

    Here’s a (cross-ENSO) summary of the flow & shape changes:

    …and that just piles up into the following:

    https://tallbloke.wordpress.com/2016/02/02/paul-vaughan-noaa-corruption-of-sst-records/

    Kinetic energy — indeed.

    Theoretical Imaginations (suggested book title)
    They call it “physics” but it can’t sensibly be regarded as such.
    Mainstream academia (and supporting American climate blog thought police controlled by CLUELESS puppet-masters) rely on STRICTLY FALSE assumptions about the geometry & spatiotemporal boundary conditions. That’s how they DEFINE their “PHYSICS”. That’s their BAMBOOZLING trick on the suppressible masses. It’s shameful.

  24. Paul Vaughan says:

    I’ll need to update the STW graph sometime:
    a) it’s not just “midlatitude westerly wind” but rather a whole suite of coupled variables.
    b) 1/(J+N) (since it’s not exactly equal) should be replaced by (φ/Φ)/(J+S).

  25. Ned Nikolov says:

    Paul Vaughan, thank you for your note above (March 6, 2016 at 2:21 pm).

    We are currently working on a paper that explains the role of albedo in planetary climates from a new perspective. We show (using empirical data) that a number of fundamental a priori assumption regarding the albedo in today’s planetary science are simply wrong despite being ‘intuitively obvious’ …🙂

  26. p.g.sharrow says:

    I have been looking at clouds from both sides and can not decide if they can be a net loss or gain in energy content at the planets surface. They are an effect of the hydro charged air-conditioner that pumps energy from the surface to the Troposphause where it is radiated into deep space.
    Perhaps this is just a great deal of bother about very little. An argument about how many angels can dance on the head of a pin.

    Stephen Wilde points us to the fact that the energy density altitude sets the thermostat for our planets surface, changes in energy in or out as determined by the surface vapor pressure at sea level. Changes in sea level atmospheric pressure may be of far more importance then is presently considered for changes of local climate…pg

  27. David A says:

    PG, another affect clouds have on earth’s energy budget, which as far as I know is poorly considered, is the affect on SW radiation reaching below the ocean’s surface. W/V alone in clear sky conditions greatly reduces surface insolation.

    Clouds reduce a large volume of disparate S/W radiation penetrating the ocean’s surface. I have yet to see a study on the disparate residence time (days, weeks, months, years, decades and centuries)) of various S/W spectrum no longer reaching below the ocean surface. Without knowing this we cannot begin to know how to quantify cloud feedbacks. LWIR feedbacks to the atmosphere are virtually instant. SW radiation not reaching below the green house liquid ocean surface has a much slower response time to affecting the atmospheric T, but, due to the vastly greater residence time of said SW energy, any change can accumulate for far longer.

  28. jdmcl says:

    Don’t forget that from the early 1980s onwards we’ve reduced micro-particle emissions, probably for the first time in human history. Water vapour condenses into cloud droplets on micro-particles, so fewer micro-particles emitted means less cloud. (Think of London’s pea-soup fogs that disappeared when coal burning was banned.)
    I’m amazed that scientists know this but ignore the reduction in emissions. It’s rather like cleaning a dirty window and then wondering why it lets more light through.

  29. AlecM says:

    @jdmcl; on the contrary, Asian industrialisation with no desulphurisation of coal fired power stations led to a massive increase of [CCN]. This is why we had 0.3 K global warming in the 1980s and 1990s. [The real sign of the AIE is reversed compared with IPCC beliefs, easy proved.]

    It stopped when the density of particulates became so high, Brownian Motion caused coarsening, plus secondary optical effects.

    Because that warming has been wrongly interpreted as from CO2 is why the Climate Models have so demonstrably failed.

  30. erl happ says:

    Re cloud. Consider this: Earth is 3% closer to sun in January and yet this is when the average temperature of the Earth as a whole is coolest. It is at this time that cloud albedo is greatest.

    Obviously cloud feedback is negative. Clouds reflect more energy than they trap. Cloud can reflect up to 90% of incident solar radiation.

    Atmospheric absolute and relative humidity changes over time. Mostly according to transpiration by vegetation. More vegetation will see it recover from a long period of decline.

    Humid air travels polewards on westerly winds.

    The velocity and carry of the westerly winds varies over time and with it the latitudional position of the frontal systems that elevate moist air giving rise to dense cloud.

    The surface pressure differential between the mid latitudes and the polar regions in the southern hemisphere has been increasing for seventy years.

    The mid latitudes in the southern hemisphere have been warming and the high latitudes of the southern hemisphere have been cooling. Antarctic Ice are has increased as the mid latitudes have become drier.

    Clouds are not climate neutral..Cloud cover is forced by ozone heating of the air in high pressure cells. Ozone levels vary over time. There is a signature in the surface temperature record indicating that temperature variability is greatest in January between the Arctic and 30° south and in July in the remainder. That’s when stratospheric ozone varies most strongly..

    Ned Nikolov, I am curious about this statement: ‘ While true that the cloud cover can be influenced by solar magnetic activity’ . Have you chapter and verse?

  31. […] . Therein lies the problem – or one of them. How’s that cloud modelling going for […]

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