From the DOE/Pacific Northwest National Laboratory, a new paper in GRL saying something that doesn’t make much sense to me. As shown in the diagram above, thunderstorms transport heat from the lower troposphere upwards. The heat source at the base of the atmosphere (at the surface) is the absorption of sunlight by the surface of the Earth. That transfers heat to the lower atmosphere by conduction (a small amount), and mostly be re-radiated Long Wave IR. Heat is then transported upwards by convection, which is done by clouds (cumulus for example) and especially thunderstorms. So, given the amount of energy transport, I’m puzzled as to how they think this new theory works as a net warming, especially when all they are doing is running a model, and providing no hard data. They say:
Pollution strengthens thunderstorm clouds, causing their anvil-shaped tops to spread out high in the atmosphere and capture heat — especially at night
Basically what they are saying is that thunderstorm anvils are enhanced by pollution, probably due to increased condensation nuclei, and those anvils act as IR reflectors at night…but…they also act as strong sunlight reflectors, something that goes on every day in the ITCZ, as Willis has pointed out with his Thermostat Hypothesis, now a peer reviewed paper. Steve McIntyre also offered a view that clouds offer a strong net negative feedback here.
But when an abstract ends with this:
The positive aerosol radiative forcing on deep clouds could offset the negative aerosol radiative forcing on low clouds to an unknown extent.
I wonder how this speculation got published in the first place.
Pollution teams with thunderclouds to warm atmosphere
New simulation study shows that atmosphere warms when pollution intensifies storms
RICHLAND, Wash. — Pollution is warming the atmosphere through summer thunderstorm clouds, according to a computational study published May 10 in Geophysical Research Letters. How much the warming effect of these clouds offsets the cooling that other clouds provide is not yet clear. To find out, researchers need to incorporate this new-found warming into global climate models.
Pollution strengthens thunderstorm clouds, causing their anvil-shaped tops to spread out high in the atmosphere and capture heat — especially at night, said lead author and climate researcher Jiwen Fan of the Department of Energy’s Pacific Northwest National Laboratory.
“Global climate models don’t see this effect because thunderstorm clouds simulated in those models do not include enough detail,” said Fan. “The large amount of heat trapped by the pollution-enhanced clouds could potentially impact regional circulation and modify weather systems.”
Clouds are one of the most poorly understood components of Earth’s climate system. Called deep convective clouds, thunderstorm clouds reflect a lot of the sun’s energy back into space, trap heat that rises from the surface, and return evaporated water back to the surface as rain, making them an important part of the climate cycle.
To more realistically model clouds on a small scale, such as in this study, researchers use the physics of temperature, water, gases and aerosols — tiny particles in the air such as pollution, salt or dust on which cloud droplets form.
In large-scale models that look at regions or the entire globe, researchers substitute a stand-in called a parameterization to account for deep convective clouds. The size of the grid in global models can be a hundred times bigger than an actual thunderhead, making a substitute necessary.
However, thunderheads are complicated, dynamic clouds. Coming up with an accurate parameterization is important but has been difficult due to their dynamic nature.
Inside a thunderstorm cloud, warm air rises in updrafts, pushing tiny aerosols from pollution or other particles upwards. Higher up, water vapor cools and condenses onto the aerosols to form droplets, building the cloud. At the same time, cold air falls, creating a convective cycle. Generally, the top of the cloud spreads out like an anvil.
Previous work showed that when it’s not too windy, pollution leads to bigger clouds . This occurs because more pollution particles divide up the available water for droplets, leading to a higher number of smaller droplets that are too small to rain. Instead of raining, the small droplets ride the updrafts higher, where they freeze and absorb more water vapor. Collectively, these events lead to bigger, more vigorous convective clouds that live longer.
Now, researchers from PNNL, Hebrew University in Jerusalem and the University of Maryland took to high-performance computing to study the invigoration effect on a regional scale.
To find out which factors contribute the most to the invigoration, Fan and colleagues set up computer simulations for two different types of storm systems: warm summer thunderstorms in southeastern China and cool, windy frontal systems on the Great Plains of Oklahoma. The data used for the study was collected by different DOE Atmospheric Radiation Measurement facilities.
The simulations had a resolution that was high enough to allow the team to see the clouds develop. The researchers then varied conditions such as wind speed and air pollution.
Fan and colleagues found that for the warm summer thunderstorms, pollution led to stronger storms with larger anvils. Compared to the cloud anvils that developed in clean air, the larger anvils both warmed more — by trapping more heat — and cooled more — by reflecting additional sunlight back to space. On average, however, the warming effect dominated.
The springtime frontal clouds did not have a similarly significant warming effect. Also, increasing the wind speed in the summer clouds dampened the invigoration by aerosols and led to less warming.
This is the first time researchers showed that pollution increased warming by enlarging thunderstorm clouds. The warming was surprisingly strong at the top of the atmosphere during the day when the storms occurred. The pollution-enhanced anvils also trapped more heat at night, leading to warmer nights.
“Those numbers for the warming are very big,” said Fan, “but they are calculated only for the exact day when the thunderstorms occur. Over a longer time-scale such as a month or a season, the average amount of warming would be less because those clouds would not appear everyday.”
Next, the researchers will look into these effects on longer time scales. They will also try to incorporate the invigoration effect in global climate models.
The research was supported by the U.S. Department of Energy Office of Science. The data from China were gathered under a bilateral agreement with the China Ministry of Sciences and Technology.
Reference: Jiwen Fan, Daniel Rosenfeld, Yanni Ding, L. Ruby Leung, and Zhanqing Li, 2012. Potential Aerosol Indirect Effects on Atmospheric Circulation and Radiative Forcing through Deep Convection, Geophys. Res. Lett. May 10, DOI 10.1029/2012GL051851 (http://www.agu.org/pubs/crossref/2012/2012GL051851.shtml)
==================================================================
Here’s the abstract:
GEOPHYSICAL RESEARCH LETTERS, VOL. 39, L09806, 7 PP., 2012
doi:10.1029/2012GL051851
Potential aerosol indirect effects on atmospheric circulation and radiative forcing through deep convection
Key Points
- Aerosol invigoration (AIV) on deep convective clouds incurs positive radiative forcing
- AIV also leads to enhanced regional convergence, and a strong thermodynamic forcing
- Wind shear and cloud base T determine significance of aerosol invigoration effect
Jiwen Fan Pacific Northwest National Laboratory, Richland, Washington, USA
Daniel Rosenfeld Institute of Earth Sciences, Hebrew University of Jerusalem, Jerusalem, Israel
Yanni Ding Department of Atmospheric and Oceanic Science, University of Maryland, College Park, Maryland, USA
L. Ruby Leung Pacific Northwest National Laboratory, Richland, Washington, USA
Zhanqing Li Department of Atmospheric and Oceanic Science, University of Maryland, College Park, Maryland, USA
Abstract:
Aerosol indirect effects, i.e., the interactions of aerosols with clouds by serving as cloud condensation nuclei or ice nuclei constitute the largest uncertainty in climate forcing and projection. Previous IPCC reported negative aerosol indirect forcing, which does not account for aerosol-convective cloud interactions because the complex processes involved are poorly understood and represented in climate models. Here we elucidated how aerosols change convective intensity, diabatic heating, and regional circulation under different environmental conditions. We found that aerosol indirect effect on deep convective cloud systems could lead to enhanced regional convergence and a strong top-of-atmosphere warming. Aerosol invigoration effect occurs mainly in warmed-based convection with weak shear. This could result in a strong radiative warming in the atmosphere (up to +5.6 W m−2), a lofted latent heating, and a reduced diurnal temperature difference, all of which could potentially impact regional circulation and modify weather systems. The positive aerosol radiative forcing on deep clouds could offset the negative aerosol radiative forcing on low clouds to an unknown extent.
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Thunderstorms – Nature’s “tower CPU heat sinks” – full stop.
I think Larry Ledwick (hotrod) is on to something. Being in the Texas Panhandle, I see similar forces at work. I’ve long bought the pollution induced thunderstorms, but summer storms of any type ( to my admittedly limited knowledge) tend to die off once solar heating goes away. This study assumes the anvils last throughout the night. My personal experience (again, limited globalwide) says that the anvils are gone by nightfall. There would be a large dissipation of low level energy through the thunderstorm mechanism, then once it’s done, it’s done. No anvils at night to trap any heat. Again, personal experience YMMV.
These guys are what’s left of the AGW science movement….stragglers. It’s wonderfully anticlimactic.
Heat is not even a minor motivation for dealing with air pollution, Everyone knows pollution is not good for health reasons. That’s why we have the Clean Air Act in the US. We’re already doing our part.
Cutting edge (young) Environmentalists are now running toward the new “hot field” of “sustainability”. My son is taking an intercession course this summer as part of his engineering program. It’s sustainable engineering practices. The text has a few scattered references to climate change, but appears primarily focused on efficiency (in materials and energy).
If sustainablility is about the most efficient use of energy and materials, I am all for it.
I doubt that the UN will find a way to tax us all based on some sustainability index, and so I am encouraging my son to learn what he can about it..
I see several flaws in this, but the main one, is that if aerosols are seeding smaller droplets (and its generally accepted that in some cases this occurs, but not in other circumstances) and impeding precipitation that would otherwise occur, then the hydrological cycle is slowed, because water that would otherwise fall as rain and be available for evaporation again, stays in the cloud.
Many, myself included, think the hydrological cycle controls the climate. Slowing the evaporation/precipitation cycle will result in less heat transport upward in the troposphere and less heat loss to space, warming the climate.
I suspect this is the primary effect and radiative effects are secondary, but in mainstream climate science, radiative effects are always primary. So says the dogma (aka theory) and the models.
Formation of these ‘anvil’ clouds requires both surface heating and sufficient water vapour in the column of air above the ground. Absent the second, no matter how hot the surface gets, you will have a cloudless sky.
“The positive aerosol radiative forcing on deep clouds could offset the negative aerosol radiative forcing on low clouds to an unknown extent.”
Help me with this scientific proposition, please, I am struggling with it mightily. English is (obviously) not my mother tongue, so when poetry is involved I may miss the finer details. Therefore in cases like this I can’t help but resort to strict logical analysis.
First let’s take the structurally much simpler proposition “The positive aerosol radiative forcing on deep clouds offsets the negative aerosol radiative forcing on low clouds to an unknown extent.”
It has the logical form of “(positive) A offsets (negative) B to extent X” which is logically equivalent to the proposition “A + B = X”. Translating it back to plain English by substituting the descriptions above to variables yields “The sum of aerosol radiative forcing on deep and low clouds is unknown.” Honest enough.
Now back to the issue of “could”. What is its role as a modifier in the sentence above?
The logical form we are dealing with is “(positive) A could offset (negative) B to extent X” now. Is it fair to transform it like “(it is possible that) {(positive) A offsets (negative) B to extent X}”? If so, we clearly get “(it is possible that) {A + B = X}”, that is, applying the same substitutions “It is possible that the sum of aerosol radiative forcing on deep and low clouds is unknown.”
In alethic modal logic the proposition “It is possible that M” is understood as “M is true in at least one world accessible to our own”.
With this we get “The sum of aerosol radiative forcing on deep and low clouds is unknown in at least one possible world given the facts of our own.” It may well be the case that this stuff is in fact unknown in our world, but since it is a widely held stance that the accessibility relation is reflexive, there would be no justification whatsoever for using the modifier “could” in the original sentence. Therefore the author may allow for the possibility that “The sum of aerosol radiative forcing on deep and low clouds is in fact known in our world, but there is another world accessible to it where it is not.”
However, at this point it gets complicated beyond comprehension for me and my mind simply melts down. Could any of you kindly help me out?
I was under the impression that the anvil heads were horizontal sheer at a particular altitude.
JKrob says: May 18, 2012 at 1:40 pm
“…Previous work showed that when it’s not too windy, […]Collectively, these events lead to bigger, more vigorous convective clouds that live longer.”
Sorry, but this paragraph make *NO* sense at all! […] Then there is this doosie – the small droplets “…freeze and absorb more water vapor”. What in the world are they talking about?!?!?
Jeff
I agree with you Jeff. As regards your last question, I’m not sure what they are talking about, but we call it hail. Seriously, hail is just droplets that get swept up until they freeze and then grow to gain enough mass to overcome the updraft and fall as hail. Some hail is clear high-density ice, other is granular low-density ice, and often a combination of the two.
My first thought was that I could see high cloud cover having an insulating effect at night, and a solar-reflective inpact in the day. So, a net cooling in daytime, a net warming at night.
However, if we assume the same ammount of cloud cover, would’t we have to assume that every square meter of cloud is receiving as much electromangetic energy from the earth at night as it does from the sun in the daytime? Yet, the energy density per square meter of sunlight is far higher than earth’s nighttime IR.
Also, what time of day do most thunderstorms occur? Afternoon, which is daylight.
Also, hasn’t it been shown that cloud cover in general gives us net cooling?
Seems to me that the net effect would be opposite of what they are claiming.
I have a little puzzel that may be related.
Tarawa is an atoll in the central Pacific Ocean, part of the Gilbert and Ellice Islands. At the moment it has a few minutes more than 12 hours of sunlight per day. It is about as close as you can get to being part of the equatorial ocean, and not get wet.
This is the (predicted) hourly temperature;
http://www.timeanddate.com/weather/kiribati/tarawa/hourly?hd=w
and the weekly temperature cycle;
http://www.timeanddate.com/weather/kiribati/tarawa/hourly
Can anyone explain when the temperature drops at sunset, then rebounds?
I have to agree with Keith Pearson and Larry Ledwick. The Summer afternoon thunderstorms form around 2:00 pm and dump on us somewhere around 4:00 pm. Yes you get clouds at night but they aren’t the massive convective thunderhead clouds that form in the Southeast on many a summer afternoon.
Do these guys even know there are different types of clouds? It doesn’t sound like it if they think thunderhead clouds make though the night very often.
Even when you do get thunderstorms in the late summer evenings it will knock 10 degrees F at least off the temperature very quickly. I only remember clouds “warming” the evening in the winter when the temperatures are around freezing.
Hey, it’s unusual in my opinion that a warmest based work actually addresses the idea that night exists at all.
I suspect what is being conveniently missed here is the contribution of condensed water and condensing water to the radiant energy escaping from the upper atmosphere to outer space. As far as I know, there has been no attempt to run experiments on condensing water vapor to see if the electrically driven molecule to molecule condensation of two water molecules do not have a tendency to produce photons much the same as two magnets can come together with a ‘click.’
Granted, this would not be an easy experiment to do as it would require a continuous condensation chamber, and sensors in a cooled environment so that they could detect this radiation. I assume this has not been done as I find no mention of this possibility in standard texts.
All that heat being released by condensation must go somewhere. As radiant energy, at least half of it should be making it to outer space. MODTRAN, which I believed to be modeled on a typical atmospheric profile, shows progressively increasing outgoing radiation with altitude such that, in clear air, about 4/5 of the outgoing radiation actually originates in the atmosphere. Mysteriously, there are no water vapor absorption bands, only the solitary CO2 ‘hole’ in the middle of the band and a minor ozone ‘hole’ on the upper fringe.
Outgoing radiation is what you have left after you subtract the back-radiation,seen looking up, from the upward-radiation, seen looking down, at any level.
“…Heat is then transported upwards by convection, which is done by clouds (cumulus for example) and especially thunderstorms.”
Convection will take place with or without clouds. Clouds will transfer more heat, if there’s enough water vapor present.
Larry Ledwick has described what I love best about crossing western Kansas and eastern Colorado in the summer. And when you get to be in these phenomenal thunderstorms, you see how much the temperature drops. I also have not seen these anvils last a really long time–they seem to do their job and dissipate when they are done. But really, this study lost me when they discussed “methodological studies”. I assume those are modeling studies. So did anything really happen in real life?
As Larry Ledwick says, have these people ever experienced a bad thunderstorm? Whether on land or at sea when one arrives it turns a hot day into a very chilly event. A big dump of hail into a tropical garden can freeze solid and take so long to melt that it kills the plants. Likewise on deck it can block your scuppers and freeze solid, making life cold and miserable for hours after.
Bad thunderstorms don’t always include hail but they are always cold.
Oh Boy…. This is what happens when common sense is replaced with nonsense and is actually taken seriously.
Lindzen & Choi, Spencer & Braswell, Svensmark and Allan’s papers all show clouds have NET negative feedback effect on Earth’s climate.
Dr. Allan’s paper published last year calculates clouds have a NET feedback of -21 watts/M^2, which is huge.
This paper is just another example of climate model parameters being manipulated to make the computer generated line go from lower left to upper right. Complete GIGO.
I forgot what statistician said this, but he said, “Given four parameters, I can make a line look like an elephant. With five, I can make his trunk wiggle.”.
And so it goes…..until it doesn’t…..
Or angling for angels? With logic hooks? 😉
At last, someone mentions this. Those huge anvil heads are ideal and potent radiators. Their insulating effect is trivial by comparison, because they are being powered by massive condensation/freezing latent heat transfer.
Larry Ledwick (Hotrod)’s description of what happens in a decent-sized thunderstorm really says it all about the major method of upward heat transference and heat loss to space in the hotter, more humid parts of the world.
You only have to struggle through a November morning’s fieldwork in northern tropical Australia to experience this first hand. You spend half the morning under burning sunshine, sweltering in 38 degree heat and intolerable humidity, wishing you had asbestos gloves to handle rock samples and tools. Then the thunderheads start building, so rapidly that the chopper gets grounded back at the fuel dump, leaving you stuck out in the open somewhere north of Wolf Creek. And then it drops on you: thunder, lightning, freezing rain and large hail, for fifteen or twenty minutes, with nowhere to go and nothing to hide under that is over eight inches high. At the end of which you find yourself standing ankle deep in ice, soaked to the skin and shivering half to death, in exactly the same landscape that was unsurvivably hot barely an hour before.
It is very impressive when experienced at first hand. All that heat goes up and away in a very short space of time, and what comes back down to the surface in its place is very cold indeed. The transfer medium is water vapour, the upward transport mechanism is convection, and the heat exchange mechanisms at the top of the system is the phase change from water vapour to liquid water and then from liquid water to ice. After which the (cold) water/ice comes back down on your head, whilst the heat goes on up.
It is the water in the system that carries the enormous upward transfer of energy, as latent heat, and its phase changes at the top of the storm that liberate it at high altitude. It is an incredibly efficient, rapid mechanism for cooling the earth’s surface, and it only works in one direction.
And once that energy is liberated at the top of the storm, as radiant heat, this can warm the colder air there and make it convect upwards, or it can radiate straight on up into space, but it cannot radiate back down to the surface, because there is a big white cloud underneath it that will simply absorb a bit of the radiation and reflect the rest back up.
In the tropics the temperature is regulated by such systems for much of the year, and they seem to be a very effective thermostat, which is why Jakarta, Singapore, Bangkok and Darwin in summer, have such a monotonously appalling climates and are such horrible places to have to cross the street in a tie and a suit: “31C and 79% humidity again.. yuk!”
But I think it probably is the incredibly powerful thunderstorm system that moderates global temperature, dominating climate where most of the sun’s heat comes in, at the tropics. And the only thing that might really be able to upset this temperature regulation mechanism, would be something that directly affected the rate or efficiency of the phase change from water vapour to liquid water (and thence to ice). In which case pollutive aerosols might have an important role, and Svensmark’s mechanisms might have a very important role indeed.
Besides which, you really can’t beat a good thunderstorm for pure entertainment!
The claim seems to be basically: during all stages of the storm’s life cycle, there is a heating “greenhouse” effect due to IR, but the IR dominated tops outlive the storms they originate from, thus time integrated effect will be dominantly in IR. Well maybe, but I think that one needs extensive observational data to verify that hypothesis. Models aren’t really cut out for this.
A question for the cloud experts here. Clearly cloudy nights tend to be warmer than clear nights. It seems to be accepted here that the clouds are causing the low level warmth (through back radiation or some other means.) I had always thought that low level moist air caused the clouds. Ie. when night fell and the suns heating went away the warm/moist air that was high enough to be close to condensing during the day actually condensed. This then created coulds or made existing clouds thicker.
So is it the low level/moist air which causes the clouds or the clouds which cause warmth at low levels?
Seriously this is a real question.
Adendum to previous question. The discription of the thunderstorms is that warm moist air rises, the moisture condenses and the clouds form. So the warm moist starts the process. It seems like it is the electric car with the fan (perpetual motion) to say the the warmth is caused by the cloud which creates the updraft to create the cloud.
The most obvious question to ask of this paper is “what validation & verification has been performed on the model?”. How do they know that what they see in the model is an accurate representation of what happens in the real world?
I assume that they must have lots of observational data relating to real thunderstorms, and that they have measurements of “pollution” (whatever that is) in the air associated with these storms, plus measurements of the radiation associated with these storms, both by day and by night. How well does their model relate to this data?
If their model verifies and validates well, then surely there is no need for them to have the statement about the “unknown extent” of the “positive aerosol radiative forcing” caused in these thunderstorms. They would know for sure.
Of course, if their model does not verify & validate (or none has been done…), then all we have here is yet another interesting hypothesis to put on the pile with all the other glittering baubles.
DocMartyn says:
May 18, 2012 at 7:12 pm
“I have a little puzzle that may be related.”
reply————————
I think what you are seeing is a shift in wind direction and speed effects bringing in warmer air off of the lagoon which is slightly warmer? ( have you measured it?) than the open ocean and on shore / off shore direction shifts when a slow wind is out of the west at night it stabilizes to the lagoon temps, when out of the North, South or East it is set by the temp of the open ocean.
I think the sunset drop then pop back up is due to the dieing of the thermal driven on shore breeze.
Looking at the corresponding wind directions and speeds as well as large storm systems just off shore will solve you little puzzle.
Using common sense in an attempt to discredit a paper in Geophysical Research Letters is one thing. Formally stating issues with the research in the form of a rebuttal paper on how their methods are flawed is another. Offering an alternative explanation is also another matter.
Along with the several objections above, my main objection in the reporting is that these scientists are said to have shown results that are treated as facts or data. It bears repeating: models cannot generate facts, and their results are not data in the sense that real world measurements provide data. Models generate calculations, which then might be compared against real world measurements as a test of the usefulness or truth-value of the models.
Without comparing their model-generated results with real data, they have only created some specificity for their models, but no enlightenment for science in general.
How hard would it have been to take some measurements of temps at various altitudes before, during, and after storms, including observing whether daytime storms produce substantial increased cloudiness at night? I guess they would have to get away from their computer consoles and make contact with the real world, and hey, they are climate scientists, so we cannot expect that.
They are looking for a hook to hang all the problems of the world on. Once found they can call all those that disagree with them the nasty people. They can then say look at us were the nice guys, we are were doing something to save the world, not like those nasty people. There politics is a religion and like all religions they want to feel special and nice. This may fail but they will keep trying other ideas. Calling these fools scientists is an insult to science. Any paper that publishes this nonsense can never be called a scientific paper. none of these people are scientists they are religious zealots.
They will never go away as humans need believe something.
Just means that freedom of speech must be protect as it is the only thing that protects us from ourselves.