Guest Post by Willis Eschenbach [See update at end]
From the Ministry of Settled Climate Science, I came across a most fascinating press report entitled Surprise Discovery Reveals a Whole New Source of Evaporation. Seems that scientists have noticed that light alone can evaporate water. I always figured they knew that, it only seemed logical to me. Light strikes a water molecule and has enough energy to knock it loose from the liquid surface. I even made a graphic of it somewhere in the past, but it’s lost in the mists of time.
Seems like it wasn’t known, though. Turns out there’s something called the “Thermal Limit of Liquid Water” which was believed to give the maximum evaporation rate for a given temperature and vapor pressure.
But if the water is exposed to light, the Thermal Limit can be exceeded. And not by a little. In one study they induced evaporation at 278% of the Thermal Limit.
White condensation on glass as green light evaporates a water-laden hydrogel. (Tu et al., PNAS, 2023)
There are a couple of big implications of this if the early experiments are verified. One is that it will make solar desalination much cheaper. Given the planet’s population and current water scarcity, this is huge news.
The other is that it’s going to mess with climate science. Consider the water droplets at the top of the clouds. Normally, when water evaporates, it cools the surroundings. But if some of it is evaporating without changing temperature … it’s gonna change the energy budget numbers.
I mean, before this you could say “X mass of surface water evaporated cools the surrounding by Y amount. When it condenses in the clouds it releases the latent heat and warms the cloud bases. And when the cloud evaporates, it cools the surroundings by Y amount”.
But with this new finding, both the first and last steps, the steps involving evaporation, are more complex. Now it seems that some of it evaporates without cooling the surroundings.
Not sure what to think about all that. My first question, unanswered in the press release, is:
Does the same hold true regarding longwave thermal radiation? My guess is no, but who knows?
My best to all,
w.
[UPDATE—Thanks to Johanus in the comments for pointing out that the draft version of the full paper is available here.]
There you go again Willis, seeing that loose thread poking up from the tightly sewn-up bag that wraps up all the “settled science”, then pulling at it so that it starts to unravel.
If you’re not careful, the whole bag will come undone.
And then where will we be, huh?
More enlightened?
Groan
The MIT researchers were initially skeptical of this find, but after experimenting themselves they realized some other force must be afoot. Digging further, the team found that the production of light without heat, using a flow of photons, can evaporate liquid water in the lab.
This is a fascinating finding because while liquid water has a knack for absorbing heat energy, it isn’t known to absorb much light. That’s why you can see the ocean floor from several meters above when there is no silt and lots of sunlight.
It’s not really settled at all then, is it?
Go look at so-called “structured water”, where a thin plasmic film develop in water exposed to light, not only perfectly purifying that layer, but also creating an electric dipole.
The further science develops, the more we learn that magic is real… No, not the Wicca/ Caballah nonsense, REAL magic, like resonant morphology, or interferometry.
And always the “magic” phenomena is eventually found to NOT break any rules of thermo or physics….
Yeah…it’s like, magic!
Arthur C Clarke quote required.
My son sent me an article on that yesterday, a process engineer asking the opinion of his retired heat transfer engineer father….my response was this:
”…sounds like techno wordplay to get some research grants from stupid bureaucrats ….photons can bounce molecules out of a water surface without “heating” it as measured by a bulk fluid temperature thermometer. Water at it’s boiling point isn’t technically “heated” but molecules are bounced out of the surface, mostly by molecular collisions, but those molecular forces are the result of photons being exchanged….The whole basis of the Planck curve is how much electromagnetic radiation (photons) is emitted by a substance at a given temperature.
MIT seems to be full of grant seeking announcements these days…”
I would add to this that enhanced evaporation from various surfaces has been the topic of thousands of research papers at many universities and research institutions, and that “achieving an evaporation rate 278 percent higher than liquid water” is no big deal in many of those tested surfaces. Newly minted “researchers” often think they are at technology’s leading edge when actually they are century behind.
“it isn’t known to absorb much light. That’s why you can see the ocean floor from several meters above when there is no silt and lots of sunlight.”
But it does absorb the light and that’s why it’s dark past about 100m
Just remember that all those biologics and minerals play a role.
Of course. Pure water is a weak absorber, but its been measured and reported in scientific papers.
Good points here about clouds.
And, “Does the same hold true regarding longwave thermal radiation?”
This is indeed the $64,000 question.
I think “yes.”
I think “Mostly No”.
The longer the wavelength the less kick it has. There is a level where it has not enough kick to get the effect to happen at any significant numbers.
You might be right in respect to a wavelength-dependent “photomolecular effect”.as hypothesized in the study.
The study used green light which is not as high energy as blue or ultraviolet light, but far higher energetic photons than any frequency in the infrared spectrum.
No hypothesize, an actual experiment conducted demonstrated the effect.
Now, all they have to do is document at individual molecule interactions.
So you seem to be saying MCourtney that evaporation is a quantum process and if the quanta hitting the surface is less than some limit associated with water molecules, evaporation will not happen? We also know that IR cannot penetrate water more than a few molecules deep and that the temperature within a few molecules deep in a water surface are ever so slightly cooler than the temperature deeper within the surface. So what is happening to this too-small quantum photons energy?
…and now I wish we still had the EDIT option, so I can fix my idea, and work yours in….
‘frexample: If the photon has so little energy, what prevents it from being energised by the water molecules, causing that small cooling you mention?
Well, it has enough “kick” to warm up the water, but maybe the phenomenon under question would be drowned out by the faster thermal evaporation?
I find it sad that the actual study, as contained in the link (that has a link, follow that link etc), did not present me an obvious bandwidth analysis.
Thermal radiation is strongly absorbed by water in solid, liquid and gas forms. What thermal radiation does not do is heat water, save the top few microns which evaporate.
I agree the answer is “yes”. Specifically, the 3.7 watts/m2 of energy supported directed downward by a doubling of CO2 will lead to increased evaporation. It doesn’t heat the surface, it enhances the water cycle.
The extra water vapor is carried upward in the atmosphere by stronger convective forces where it increases cloud thickness. This extra condensation also reduces water vapor high in the atmosphere where its greenhouse effect strongest. Thus, less energy is absorbed countering the increased energy from the higher condensation rate.
The net of this process is the extra energy climate science claims will warm the Earth is instead used to produce a little more precipitation. The extra energy CO2 absorbs is transported high in the atmosphere and balanced out by reduced water vapor energy absorption.
Well, there has been a lot of “settled” science thru the years… epicyclic planetary motion, phlogiston creates fire, surgeons have no need to wash their hands between surgeries, luminiferous aether, Rutherford’s observation that there was nothing else to be discovered (about 1905, I think), man will never fly in a thousand years (NY Times, 1903), etc, etc. In every case, ONE guy proved each wrong, disproving thousands.
The US patent office said in 1899 that there was nothing left to be patented.
Usually attributed to Lord Kelvin in about 1900 and just before Planck and Co opened a whole new can of worms, but there is some doubt if he did say it at all.
“it’s gonna change the energy budget numbers.”
No, conservation of energy still holds. Incident light brings energy that was going to be converted to sensible/latent heat somewhere. This claim says that it can be converted directly to latent heat without a stage of sensible heat causing evaporation. That doesn’t change the amount of energy added to the environment.
I’m glad we agree on the First Law, Nick. This one seems a bit silly and doesn’t improve much with further reading, as I comment below.
“No, conservation of energy still holds.”
I’m not sure Willis is claiming that. Changing the energy budget numbers could be more evaporation and less incident heating. Tweaking the numbers but still in balance.
It is incident heating that sustains normal evaporation, so there would be correspondingly less of that.. This mechanism would not change outcome. It’s down at the level of reaction mechanisms in chemistry. You can have different pathways, but the thermodynamics is the same.
A little less evaporation and also a little less OLR. Vs. More direct evaporation.
It’s a numbers dance.
I think, Nick, the take-home lesson for you and your fellow travellers is this:
Your infernal little models are increasingly being exposed as video games for nerds, with near zero relation to reality.
But I await your canounies’update of their model. It will probably happen as soon as you stopped your urgent discussions on including all those weather modification programmes and atmospheric spraying plans…
What the hell am I saying? You guys don’t even bother with the sun more than measuring a simple radiation spectrum.
Thanks, Nick. We agree on the First Law.
However, if you are running calculations regarding the previously understood incorrect relationship between temperature and evaporation rate, as is done by say climate models, it will indeed change energy budget numbers …
To a first order, the evaporation rate of water E is proportional to the square root of temperature. Yes, there are a variety of other factors, the main ones being pressure, humidity, dew point, and wind speed.
But if the early experiments are correct, and you’re running evaporation calculations every half hour as climate models do, you’ll get too little modeled evaporation during the day compared to the night.
No violation of the First Law … just another bad model.
w.
“That doesn’t change the amount of energy added to the environment.”
Neither does CO2.
Bazinga! CO2 doesn’t control the sun or the clouds for determining the incoming short wave, i.e, the low entropy, or work capable, energy.
Given that, how do we know that odd assumptions about long wave power redistibution actually correspond to a significant real temperature effect?
You just pretty much nailed it. Stokes can argue thermodynamics all he wants but an increase in temperature implies an increase in energy. Both Planck’s Law and the calculation of enthalpy have a direct relationship with temperature. CO2 figures in neither of these relationships since it is not a heat source, it can only regurgitate what it has received.
Tim Gorman: “CO2 figures in neither of these relationships since it is not a heat source, it can only regurgitate what it has received.”
WR: To warm the surface after absorption of surface-emitted energy, atmospheric CO2 has to cool the atmosphere. After first having warmed the atmosphere by absorption, CO2 (or another greenhouse gas) brings back that energy to the surface. In case this happens this is a closed loop: the atmosphere did not warm and the surface did not cool.
In case CO2 did not bring back absorbed energy to the surface, the surface did cool. In that specific case, there is no greenhouse effect for the surface, at most there is greenhouse warming for the atmosphere but just in case no other cooling process becomes activated.
What happens when a greenhouse gas absorbs surface radiation is that absorption prevents that amount of energy from escaping into space. Absorption causes a delay in heat loss. As a consequence, more energy remains at or near the surface until ‘other cooling processes’ (convection or advection of latent and sensible heat) move away [excess] energy from that location. As a warmer atmosphere enables more water vapor, processes like convection and tropical cloud cooling become activated as soon as more water vapor enters the local atmosphere. As soon as the atmosphere is warmed, there is more room for water vapor: evaporative cooling will take place directly and other cooling processes become activated as well.
“ As a consequence, more energy remains at or near the surface until ‘other cooling processes’ (convection or advection of latent and sensible heat) move away [excess] energy from that location.”
This misses the point that the amount of radiation from the surface is temperature related. If the temp stays high from slower cooling then the amount of radiation it emits also stays high. It’s not just convection or advection that is in play.
So much of the “back radiation” theory seems to be based on the assumption that the radiation from the surface is a constant – typically an amount based on the mid-range daily temperature. But that is misleading. Nighttime radiation closely resembles a exponential decay meaning that the higher the starting temperature of the decay the higher the radiation amount is. If that decay factor is slowed down the rate of radiation remains high over a longer period of time. The total amount of radiation is the area under the exponential decay curve and that will grow if the curve doesn’t decay as fast.
Averages hide *so much* of what is going on that it is unbelievable. And climate science depends on averages that aren’t even averages. The average of the daily temp curve is not the mid-range value. The daytime temps are a sinusoid and the nighttime temps are an exponential decay. The mid-range value captures none of this.
Tim Gorman: “This misses the point that the amount of radiation from the surface is temperature related.”
WR: As the temperature rises, the percentage of surface radiation reaching space without being absorbed diminishes strongly: main greenhouse gas water vapor rises by 7% (per Clausius-Clapeyron) which results in a strongly diminishing efficiency of surface radiation especially where we find the least water vapor: at the poles and over deserts. When the greenhouse effect rises, the higher quantity of surface radiation results in a lower quantity of surface radiation reaching space. The actual quantity of surface radiation reaching space by the atmospheric windows is 40 W/m2 (old number Trenberth et al.) and 22 W/m2 (new number). For the last number: surface radiation 396 W/m2, efficiency 22/396 = 5.56%. Compared with an Earth without a greenhouse atmosphere that also absorbs the actual number of 161 W/m2 of solar energy: surface energy directly reaching space is 161/161 = 100%. A (rising) greenhouse effect results in a smaller role of surface radiation in surface cooling.
Water vapor H2O is the main absorber and so the main cause of the greenhouse effect. A rise in temperature by 1K or 0.3% results in 7% more water vapor. A rise in temperature results in less surface radiation reaching space, both in % and in W/m2. Radiation is not only a minor player in actual surface cooling, its role diminishes when the surface warms.
The higher the greenhouse effect, the smaller the role of surface radiation in surface cooling.
“As the temperature rises, the percentage of surface radiation reaching space without being absorbed diminishes strongly:”
This isn’t just an issue of how much surface radiation reaches space. The atmosphere is an intervening media between the surface and space. If the surface temp rises then so does its rate of radiation, see Planck. It is the intervening atmosphere that gets that radiation that doesn’t reach space. Thus the atmosphere can warm while the surface actually doesn’t.
The rise in surface temp by climate science and the climate models *still* doesn’t take into account the shape of the daily temperature curve at the surface. It *is* radiation driven. It’s why the daytime temp is a sinusoid, it follows the path of the sun and the sun’s radiation. It’s why the nighttime temp is an exponential decay and follows the radiation from the surface. If the surface temp was mainly driven by convection and advection the shape of the surface temp curve wouldn’t look like it does.
Tim Gorman: “This isn’t just an issue of how much surface radiation reaches space”
WR: You said: “This misses the point that the amount of radiation from the surface is temperature related.” And I said: if radiation is at rising temperatures a diminishing factor in surface cooling, radiation can hardly play a role when surface temperatures are rising. Therefore I only mentioned the dynamically enhancing cooling factors: evaporation, convection, and tropical cloud cooling. Enhanced surface emissions that do not reach space but are absorbed near the surface, neither cool the surface nor the Earth.
I agreed with your “CO2 figures in neither of these relationships since it is not a heat source, it can only regurgitate what it has received”. When absorbed surface radiation warms the air, the surface becomes cooled. But when atmospheric back radiation warms the surface, the air that delivered that energy cools. No energy is created, it simply isn’t lost to space and can go back and force from the surface to the atmosphere. Unless ‘other cooling factors’ like all H2O-related surface cooling start to jump in. And they firmly do, when surface temperatures rise by just a little bit. Other cooling factors than radiation set surface temperatures in the case of a greenhouse atmosphere based on mainly water vapor and a surface area dominated by oceans.
Your scenario is flawed. If water vapor plays a role, then pan evaporation would be increasing. Instead, it is decreasing.
Jim Masterton: “If water vapor plays a role, then pan evaporation would be increasing. Instead, it is decreasing.”
WR: Jim, would you like to explain the sentences above in more detail? “If water vapor plays a role”: in what? What exactly about pan evaporation?
I thought you were supporting EGE (enhanced greenhouse effect). In that scenario, water vapor does the heavy lifting instead of CO2. If you now don’t support EGE, then I’m not going to play that equivocating game with you.
As for pan evaporation, look it up. The current trend in pan evaporation doesn’t support EGE. Attempts to explain away the discrepancy have failed.
WMO:
“In the absence of the natural greenhouse effect the surface of the Earth would be approximately 33 °C cooler.
The enhanced greenhouse effect refers to the additional radiative forcing resulting from increased concentrations of greenhouse gases induced by human activities.” (Bold added)
WR: My take:
In the absence of natural surface cooling based on the H2O molecule, the surface of the present Earth (with the actual greenhouse effect) would be 202°C warmer.
Enhanced surface cooling refers to extra surface cooling resulting from higher surface temperatures.
The full paper is paywalled by PNAS (direct link), but the abstract includes :
I agree with your “fascinating” reaction to this story, but what I would really like to see is their complete “evaporation rate versus wavelength” curve, especially if they include what the “Thermal Limit” predicts for comparison purposes …
…the lack of which unfortunately firmly removes the report/s from the realm of good science.
But the evil of the priest diminishes not the holiness of the sacrament, so the information remains interesting.
The full draft is here: https://arxiv.org/ftp/arxiv/papers/2201/2201.10385.pdf Forty-five pages, with supplement describing data and experimental setups.
Evaporation rates are charted in Fig. 2, vs various wavelength and source ranges.
Thanks, Johanus, much appreciated. I’ve added the link to the head post.
w.
Echoing Willis, many thanks for digging out that link.
Attached (for expediency) is a screenshot of Figure 2 from the preprint, with panel “D” showing the Thermal Limit line I asked for.
From the caption …
This is expanded further in the “Main Text” of the paper ‘(on page 5 of the PDF file) :
Unfortunately it looks like their “enhanced evaporation rate” does not apply to bodies of open water … like the Earth’s oceans … which will only ever experience “stage I” conditions.
_ _ _ _ _
Also from the paper, on page 6 :
If those “clusters” include various “impurities” dissolved in the water … e.g. sodium and chlorine ions … than the utility for applications like water purification (/ desalination) are likely to be severely reduced.
Thanks, Mark, interesting. You say:
Hmmm … setting that question aside as being unanswered, what about water adsorbed on or absorbed by various land surfaces, soils, plants, etc?
What about water in the form of fine spray?
What about water in the form of spume or foam?
What about water in the form of cloud droplets? Each droplet has a diameter of ~ 1/100 mm and a weight of ~ 5.2E-7 milligrams, so lots of surface area per volume …
Still plenty of unanswered questions.
Regards,
w.
I was extrapolating from their “In stage I, water floods sample surface … In stage II, water recesses into pores …” characterisations in the “Main Text”.
If we replace “aerogel” with “the sea floor”, then there is up to 13 km of “flooding the sample surface” over 70% of the Earth’s surface.
Hence my, probably premature, “bodies of open water … will only ever experience ‘stage I’ conditions” conclusion.
Tru dat …
The change in evaporation rates when the water level drops enough to “recess into the pores” of their aerogel … what they call “stage II” … is by no means necessarily the same as the other physical circumstances in your (non-exhaustive) list.
My first question is are they really trying to break the First Law of Thermodynamics? My generosity makes me take the working assumption that they are not.
So what is actually being claimed?
Are they saying that they can make water evaporate faster into air that is not saturated? That is a kinetic issue, it doesn’t change the heat-in/heat-out equation.
Even if that is the case, they are working on a hydrogel. Water is not structured the same way at a hydrogel surface as in pure water, so their experiments would not be reflective of how it works on a bulk scale. The water still has to diffuse to the surface of the hydrogel. This will always be slower than in water alone.
Now I’m about to get less generous. From the media-report link;
“The amount of heat that water absorbs does not always account for all the liquid that is lost in evaporating experiments.”
My first suspicion: The air is probably not pre-saturated in their experiments. Or their experimental error is too great. I’m still betting on The First Law.
Getting more generous again, the abstract of the paper indicates they are not morons.
They are just looking at surfaces that promote more efficient evaporation. Quite sensible. Everyone should be familiar with taking some superheated water drink in a cup out of the microwave. You put a spoon in it and it violently boils, possibly causing burns. This is because the water wasn’t evaporating instantly with the energy being put in to do so. So you maybe lose more heat than necessary through radiation and conduction to the environment than just with evaporation.
In a large plant I would not expect this to be significant at the temperatures involved.
However there are simpler physical methods to do what they are attempting. Most people will also be familiar with those ultrasonic misting devices commonly sold for all sorts of applications. They are a superb way of getting water into the vapour phase, which is why they are used in medical humidifying devices.
The energy expenditure is minimal and still goes into the latent heat budget.
I doubt that trying to use visible sunlight in a non-thermal manner at a heterogeneous interface can even approach the rate increases that existing methods already provide for.
My general attitude is that this is a bit like all the fancy ways that have been explored to chemically remove CO2 from the air in a rather expensive but unrealistic manner.
The superheated water from a microwave is possible because a nucleation site is needed for a bubble of steam to form (think surface tension). This works best if you have a smooth container (no cracks, gouges to promote nucleation). First step is to heat the water to a slight boil to drive out dissolved gases, wait a couple of minutes and then start heating again – though you would often have the water explode if the microwave was running too long.
The container must also be a size and shape that allows the water to be heated very evenly so that convection currents don’t form and initiate boiling.
“They are just looking at surfaces that promote more efficient evaporation.”
Consider leafy vegetation. The interaction with sunlight AND with the (CO2-enhanced) longwave radiative coupling with the atmosphere would be an important factor for evaporation/evapotranspiration without necessarily changing temperature of either the air or the leaf, one would think.
Those ultrasonic misters are neat gizmos. They make the water pile up into a ‘spike’ and the sound waves focused at the tip of the spike blasts the water into a superfine mist. It’s like atmospheric pressure wet steam *but not hot*.
You definitely do not want to put any part of your body into the water spike. A friend read the instructions which said to not to that. So of course he poked a finger in and got a really tiny and painful bruise. The sound waves worked just as well to blast the squishy human.
Yeah, Gregg, I’ve done that painful experiment.
The interesting thing is that it can also travel through a solid barrier. When the agitation of the water is visible, it can hurt when you put your finger in it.
One of the side effects of scientific curiosity.
“Or their experimental error is too great.”
My first glance at the paper did not identify any attention to measurement error and its impact on results. I will have to read it closer to confirm that. It’s quite possible that this small result actually lies in the realm of UNKNOWN.
So I was curious. Why green light in the hydrogel evaporation example? Went and read the PNAS paper. Turns out this ‘new’ “photochemical effect” is light wavelength dependent, and is strongest at 540nm—smack in the center of the green light wavelength spectrum from ~500 to ~580.
This fact likely explains why chlorophyll evolved to be green. Maximizes photochemical produced water vapor molecules (from leaf tissue water) plus CO2 molecules (from leaf stomata) to produce simple sugar molecules.
Another of life’s little mysteries now scientifically explained.
I should go back to school, ’caused I missed the light and plants bit. I suspect I could learn much on the web, but there are other time-consuming things I need to do.
It seems that the vast majority of chlorophyll absorbs green light, but the plant also absorbs other colors (wavelengths) such as blue and red. Enough of the green is reflected such that the leaf appears green. This implies the other colors do something within the leaf.
I thought your reply was insightful. Green chlorophyll looks green because it reflects green. So I dug much deeper using googlefu and found the ‘correct’ additional information, all based on lab experiments.
Photosynthesis works only with light wavelengths between about 400 and 700nm. Blue is ~450-500; red is ~620-750.
Leaves absorb about 90% of blue and red, but only about 70-80% of green (depends on leaf), so the greater green reflectance causes chlorophyll to look green. You are correct about that.
But neither blue nor red provides the same photosynthetic efficiency as green (defined as given light plus given CO2=some measured quantity of carbohydrate). (My above hypothesis as to why green is experimentally validated.)
And neither blue nor red can penetrate deeply into the leaf (blue because water—blue sky, blue ocean, red because energy), so green also activates more photosynthesis deeper into the leaf. A new biological fact for me that further strengthens the green chlorophyll evolutionary hypothesis.
Thanks. I learn a little bit every day.
We both do
My understanding was that leaves are green, because that is reflected, the rest absorbed. I am told Weedgrowers have red and blue LEDs only, no green, it’s not needed. Weed growers are real interested in efficiencies…
So, I don’t happily agree with you, and curse you for forcing me to go spend all those hours becoming literate on a subject hitherto of non-zero but very little interest.
Go away, I have to go find out stuff now…
Yet, as you know living in Florida, there are many plants with red leaves. But I have not seen any blue leaves.
Several have blue-green leaves but there are only a few, uncommon, plants that actually have blue leaves.
I understand some police cells [in the UK, I believe] are – or were – pink as it is said to calm the more agitated – and potentially violent [to others or themselves] folk therein.
Auto
The start of the gender transition fad ??? 😉
Chlorophyll does not absorb green light, it absorbs blue (420-450nm) and red (620-680), leaves look green because they reflect green light.
Do a little reading and try again.
Phil is right. Look at the Chlorophyll absorption spectrum(s).
https://external-content.duckduckgo.com/iu/?u=https%3A%2F%2Fblog.captive-aquatics.com%2F.a%2F6a010535f11c3d970c015434697eb6970c-800wi&f=1&nofb=1&ipt=045afcb28539063f0003dc6083290cbabd730d9f14ac20649c8982e90f5d9db4&ipo=images
The colour sensitivity of the human eye also peaks at green, meaning we see it more. Always consider the observer bias.
Phil doesn’t need to read anything. If you grow green plants in green light, they will die.
So Kermit was wrong? It is easier being green?
Rud, I think vegetation is green because it doesn’t absorb green so well.
Looking at the absorption curves for Chlorophyll A and Chlorophyll B the (multiple) absorption peaks fall either side of green.
I think there are many factors to be considered insofar as radiation intensity, energy therein, and efficiency of absorption and conversion to chemical energy are concerned.
Plants have some other mechanisms for water conversation. For oceanic/lake photosynthesis it is completely unnecessary.
The initial part of the photosynthetic process is to break down water into O2, H+ and electrons. The energy from the electrons is used to produce ATP and NADPH which are energetic molecules used in the Calvin cycle to form sugars.
And Eucaryote green plants also have mitochondria. In the absence of light, they will do oxygen based metabolism like animals. The primary purpose of mitochondria is to convert ADP to ATP.
You are right–the oxygen comes from the water and not the carbon dioxide.
There is also the factor that a plant’s leaf doesn’t just consist of chlorophyll. Cutin and Cutan will alter the light absorption qualities as well.
I do not understand what is “new” here.
You cannot absorb a photon without absorbing its energy … The water receives some energy from the photon and evaporates. The question should be: for a received photon energy of x W, is the latent energy lost by evaporation higher, equal or lower than “x”. A major discovery would be that is higher, but I cannot see any figure about it …
You give a figure of “278% of the thermal limit”, but this is a different problem. In the experiment described in the paper, convective air is allowed to interact with the water. In this case, if the air is warmer, or not saturated, the water will evaporate and tend to saturate the air. This phenomenon is used in the cooling towers of fossil plants to cool the condenser by the evaporation of some water and may cool the water at temperatures below the ambiant air. In any case, the “standard thermodynamics” is complied with !
From infrared’s point of view surely visible light is just it’s shortwave cousin, so not a very surprising result I guess. Light is just a slightly different kind of heat as far as the H2O surface is concerned!
re: “The water receives some energy from the photon and evaporates”
New physics; we have moved on from Maxwell into, well, I don’t know what this ‘step’ is called. For sure we have moved away from EM (electromagnetic) energy and established (by the looks of it) physics? *
.
* Note: This is a comment and does not represent my belief OR my best argument. Nota bene.
As to the effects of light, many years ago we found anomalous results in a behavioural experiment in rats. It occurred after moving to a lab without windows and, instead, flurescent lights. We replicated the result and tried to publish, but “peer review” was very hostile and we had lots of other things to do. I suspect there are real effects of light on human performance as well.
For sure. Some people get seasonal affective disorder (SAD) in winter with reduced sunlight.
The biological effects of flickering lights was a taboo subject for your peers?
How extraordinary, how quaint, how usual…
Have you tried recovering that info, and publishing in the new system, where any fool can read and comment? What with Substack and Google blogs etc, one is free to publish, I don’t understand why academics’ egos are still so invested in a peer-review system that has been corrupted and usurped by people who say shituff like Follow the Science.
I understand that peer review is an important part of science, but sometimes, there are no peers, only people with similar qualifications, jobs or titles. We all know 96% of them never actually contribute, why value their opinions?
“The other is that it’s going to mess with climate science”
To really mess with evaporation rates at a water surface you could always try a few drops of olive oil. In 1770 Ben Franklin smoothed Mount Pond and estimated the effect:
Sorry about the formatting.
JF
Thanks, Julian. Regarding the oil smooths, I’d suspect marine algae. I find:
Regards,
w.
To get very speculative… When oleaginous plankton, especially diatoms evolved they would have altered the ocean surface. If land erosion was increased by the then tectonic conditions perhaps a major diatom bloom would have caused a temperature excursion? See the Paleocene/Eocene extinction excursion and other warming blips.
The Sea of Marmora shows what happens to sea surface temperature when a water body is overfed with sewage, agricultural fertiliser, adissolved silica runoff, and is smoothed with oil. Similarly, Lake Tanganyika. Simple oil smooth warming should be apparent wherever surface oil pollution levels are high. IIRC the Black Sea and the Baltic show this. The Eastern Mediterranean and the Red Sea look likely.
I had a piece on the TCW Defending Freedom blog entitled ‘Are We Smoothing Our Way To Global Warming?’ which has more detail.
JF
Beware the sea snot.
Do polluted aerosols rain out faster?
JF
“it evaporates without cooling the surroundings”
I guess it most probably will still cool the surroundings, but much less. If we make an analogy with wind, the wind “takes away” the most energetic molecules, leaving the cooler ones intact. The same would be with light, wouldn’t it?
P.S. How about the evaporation of snow/ice? It’s apparent to anyone who’s regularly taking winter trips in the high mountains, well below the freezing point.
It is called sublimation. Happens in dry cold air. The disappearing snows of Kilimanjaro are caused by illegal logging of its formerly tropical forested lower slopes that formerly provided humid updrafts that blocked sublimation near the peak. Nothing to do with climate change.
Hows about Antarctica?….classified mostly as a desert….sublimation going on and the snowfall must be low but accumulated over many centuries…just another complex process going on…..arctic has more precip but another complex process too.
Dry being the important word.
Water or ice will always evaporate into air that is not saturated. Sometimes slowly, sometimes quickly.
This is the basis for those dipping-duck toys. The beak is covered in a material that promotes evaporation, and they are given a cup of water to cyclically dip the beak into. The resulting thermal gradient produces an evaporation-condensation cycle of the low-boiling point liquid inside the sealed unit. And thus movement when the liquid runs back from one end to the other.
An apparent perpetual motion machine.
Of course, it is not. The energy actually comes from the thermodynamic difference between liquid water and air which is not saturated with water vapour.
That is nothing new. Direct sun light has a large impact on evaporation rates and that has been known for a long time. The funny thing is just, there don’t seem to be much data on this out there.
Anyway, the implication is the water cycle being self-regulating in a way. More sun light, more evaporation, more evaporation more clouds, more clouds less evaporation..
There are even youtube videos on the subject..
What effect could other frequencies in the EM spectrum have?
The significant fail in these folks thinking is their (strict) distinction between heat and light
It is of course a glaring example of Human Hubris – that we (us HUMANS) can see light but not heat
It impacts of course Climate Science not least in the distinction there between sunlight, Ultra violet, heat, infra-red, long-wave infrared etc etc
Everybody **knows** what these things are, just as they all know what the emperor is wearing right.
Yes CO₂ absorbs ‘energy’ but instantly either radiates it away at longer wavelength (it doesn’t because it has Zero Emissivity) or it gives the energy to other atmospheric gases and they radiate it away at any one or more of the trillions of different wavelengths.
But Climate Science doesn’t want to know that and closes it eyes to even the possibility. Once ‘heat is trapped’ – it is trapped forever. sigh
(i.e.Carnot’s Heat Engine equation even tells us what those wavelengths are as well!!!)
C’mon people, open your minds, and your mind’s eye.
These things are part of one huuuuuge continuum of electromagnetic radiation that stretches from wavelengths of hundreds of miles for ‘radio’ waves (as lightning makes) down to 0.01 nanometres for Cosmic Rays.
We’re talking a factor of One to One Hundred Thousand Trillion from shortest to long(est) in one unbroken sweep.
Just because ‘we’ can see the miniscule slice between 450nm and 650nm does NOT make us the smartest and brightest critters that ever lived – and Ma Nature did NOT divvy it up into neat little signposted sections for our, or anyone’s, benefit
How do they explain even just a microwave oven – it makes things hot without getting hot itself or having an obvious heat source – how **does** it do that? According to them.
They are children
PS Have they rediscovered the Ultraviolet Catastrophe?
Methinks they have
Common misconception. I do indeed register heat, which makes my skin the eye for IR. Before you point out that seeing needs actual eyes, I must remind you of them that can tell the colour of a paper by waving their hand (or elbow!) above it.
Science has far to go, but the journey sure is fun!
From the paper the claim is science had it wrong with…
“Later experiments and calculations, using the modern scientific method, revealed heat as a key player in that process.”
And re: light being able to cause evaporation, Willis writes
“I always figured they knew that, it only seemed logical to me.”
I concur Willis. It’s always been obvious to me that energy is needed, not “heat”. Give a molecule enough energy and it can break free.
I have to wonder whether it’s these researchers who were mistaken with their interpretation of the science rather than science in general.
Story tip
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7575229/
A very informative article by Valentina Zharkova, an eminent specialist in solar physics
If she is right, forget 2050 mythical nut zero targets, get some coal mines developed with power stations
When solar Cycle #24 went to bed, SC#25 began with sunspots in greater number than expected and have remained high, although there was a lull this past week. The numbers have been higher than predicted and higher than the upside of the predicted range.
But, it is time for a good solar physics discussion.
So, coal and gas fast, and nuclear coming along a bit more slowly.
Update the UAH graph below
But….But…The science was settled!
And is this effect reversible?
is there any conceivable mechanism that gives off light [green or otherwise], or any other electromagnetic radiation, if water vapour is ‘absorbed’ – “superlimated” if there is such a word – or thing?
Auto
One of the correct questions.
I doubt if it is ‘reversible’ but there might be other mechanisms that work in the opposite way.
For this to happen the vibrational energy due to the absorption of the light must be transferred to translational energy which gives the molecule enough energy to leave the surface. That translational energy can not be re-emitted.
Study: ): “In summary, we report an efficient 3D wavy evaporator featuring double-surface evaporation, which not only maximizes the utility of convective flow but also minimizes the heat loss to the underlying bulk water compared with the conventional 2D flat evaporator. Under convective flow, the suspended vapor on the 3D wavy evaporator surface is effectively diffused to reduce its surface humidity. Simultaneously, its surface temperatures also decrease below the ambient temperature, enabling the …”
The title of the study is: “Evaporation rate far beyond the input solar energy limit enabled by introducing convective flow”
WR: It seems they developed a special device enabling a convective (air)flow adding energy to the cooling device. Green light was used to activate evaporation but the necessary energy for evaporation (as I read it) became distracted from the air flowing along the specially constructed device. From the Abstract: “Herein, we demonstrate that a carbon nanotubes (CNTs) and airlaid paper-based 3D wavy evaporator not only facilitates the double-surface evaporation, but also can effectively diffuse the suspended vapor assisted by the convective flow, so as to reverse the heat loss and continuously harvest additional energy for efficient evaporation.”
Unfortunately, the study is paywalled. So I cannot discover whether the convective airflow of dry hot air fully delivers the extra energy needed for extra evaporation. If so, the technique is great but especially useful for hot deserts.
Willis has added a link to the full paper thoughtfully provided.
Thanks, Richard. The study mentioned by me in the comment above came from the last sentence from the link Willis gave here: “I came across a most fascinating press report entitled Surprise Discovery Reveals a Whole New Source of Evaporation.”
The added link found below the post is a link to a different study. An interesting one. As the abstract of that study says, this one is about: “the cleavage of water clusters off surfaces by photons”. Instead of evaporation of water molecules ‘one by one’ a ‘packet’ of H2O molecules is able to leave the surface by the influence of light. Important seems to be: “In this paper, we discover a photomolecular effect which makes water absorbing in the spectrum range where bulk water is least absorbing.” (Italic added).
One can wonder why in this specific situation (no ‘bulk water’) plus by the resulting higher absorption of that specific spectrum range whole ‘packets’ of water vapor can be lost by the surface. We know surface molecules are more tightly connected than the water molecules below the surface. The lack of ‘a molecule above’ means all connecting forces can be directed to the molecules aside and below: a tight connection of surface molecules with each other results. As a consequence, ‘inside molecules’ are less connected to each other than surface molecules:
Therefore the form of the ‘surface’ matters. It is known that sound waves have a peculiar influence on water: at the right frequency water surfaces change and more ‘drops’ of a water flow are lost to the surroundings. See: https://www.youtube.com/watch?v=uENITui5_jU
Another effect of ‘resonance’ is shown here: https://sebjaniak.com/resonance.html
A 20-mm drop changes its surface as explained as follows: “The vibratory movement creates eddies and flows, the parts become differentiated and organize the mass, and it is only if there is a degree of synchronization between the outward and the inward pulses that they combine to form a standing wave. The faster the movement, the finer the cellular structure.”
(I don’t know whether this example will show up: )
My question is: when sound waves can change water surfaces and drops can be separated by sound waves, why couldn’t light waves have a common effect, especially when surfaces are already changed when the experiment is done with the use of an extra medium and not with ‘bulk water’. Probably the surface of the water already changed by the extra medium. The special frequency of the added light possibly/probably introduced an extra internal movement at/near the water surface breaking surface tension for ‘water clusters’.
On Twitter: a very interesting demonstration of the influence of sound waves on a drop of water: “This shows sound waves levitating droplets of water & changing its shape due by frequencies of the waves”.
https://x.com/RTerriers/status/1708962515793670269?s=20
If an incident visible-light photon at an energy of, say 2.5 eV, is sufficient to cause evaporation of some number of water molecules off the surface of water—assuming of course such energy input is sufficient to break surface tension forces “bonding” those same molecules to the liquid surface, which I seriously doubt—then the reverse should be true. Those water vapor molecules should rapidly condense back down to liquid water due to their normal, continuous thermal radiation of photons, albeit at much lower energy per photon (on the order of 0.1 eV/photon emitted for 300 K vapor temperature).
Someone will have to work out the quantum mechanical probabilities governing such interactions and the statistical thermodynamics for the continuum phases at that complex water-gas interface to determine if net evaporation is possible for given boundary conditions of liquid water surface temperature, water partial pressure above the water surface, other gas constituents above the water surface, incident (ambient) light spectrum and power flux, and radiation sink temperature, if different from 3 K.
If there was air flow across the surface would they be able to condense back into the water or be carried in the air flow?
My faith is restored. This is why I come here. I just shut up listen an learn. Seriously.
An excellent question – now here is one about ice cream in Southern Australia. I am fortunate enough to have two refrigerator/freezers. The ice cream is soft in one at -18C and hard in the other at -22C. This apparent change of state at somewhere around -20C poses an intriguing question. As the ice cream is basically water then should this also occur in ice as glaciers and icebergs regardless of the outside temperature or is there just enough fats in the ice cream mix to effect this change of state?
I think you’ve answered your own question. Ice cream is not pure water.
They put some effort into making ice cream with desirable properties at certain temperatures.
The apocryphal story is that this was invented by Margaret Thatcher before she went into a different career path.
Almost certainly untrue, but she did briefly work for one such company.
(She was a Chemistry graduate. She studied X-ray crystallography at Oxford under the supervision of Dorothy Hodgkin, no less.)
At what temperature do ice crystals form in ice cream?
Cool! [pun intended] Add this to the ~75 anomalies of water already known:
https://water.lsbu.ac.uk/water/water_anomalies.html
Given they can’t really nail down the actual reason or mechanism of many of the above anomalies, and now this one completely screwing with the thermodynamics of climate and atmospheric energy models – I guess you should say the “science” is absolutely NOT settled!
Tripling of evaporation ? Sounds like another cold fusion mistake … especially since they have no theory as to the why …
Oh they know why, and how, but not a clue as to what it’s for?
Flash: Evaporation can be accelerated in the absence of heat or light. A cold wind will suffice. It can even cause sublimation.
The image at the top of the post is an excellent example of steam fog.
Willis: “Does the same hold true regarding longwave thermal radiation?”
WR: The quantity of back radiation is huge: 333 W/m2, double as much as solar absorption. Longwave radiation is nearly completely absorbed in the 0.01mm just below the surface. That layer should be hot – unless it is cooled by evaporation.
This seems another process but who knows specific frequencies of longwave radiation play a role as well.