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Author Topic: Humidity, CO2, and cloudcover. And cosmic rays ?  (Read 4356 times)

Offline yor_on

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Humidity, CO2, and cloudcover. And cosmic rays ?
« on: 04/07/2011 01:35:39 »
This is a wondering I've had for some while now. If we assume a warming, there must be a lot more humidity in the air. What will it do for cloud covers?

So I looked at it, and I'll present what I've found so far, to see your thoughts. When we speak of clouds we have different kinds, generally defined by their altitude. "Over the course of a year, the amount of sunlight entering the Earth system equals the amount of radiant energy reflected and emitted back through the top of the atmosphere (Harrison et al. 1993). The sun beams an average of 340 watts per square meter to the Earth and, in turn, our world reflects 100 watts (or the equivalent of one light bulb) per square meter back up to space. The remaining solar energy (240 watts per square meter) is stored as heat within the air, oceans, and land surface and, gradually, emitted back up through the atmosphere to space."

And "At any given time, a small sea of water floats above our heads in the form of clouds, ice, and water vapor. The form and position the water takes in the sky changes the way it interacts with solar and thermal radiation. Clouds, especially low-lying, thick clouds, reflect an enormous amount of sunlight back into space and keep it from overheating the Earth.

High-flying, wispy clouds and water vapor absorb greater amounts of outgoing thermal (heat) radiation, which is generated by the surface of the Earth after it is warmed by the Sun. Along with greenhouse gases, such clouds and water vapor contribute to keeping the average temperature of the Earth’s surface from dropping to Arctic levels year round."

So there are two effects here, one cooling (low clouds scattering radiation from above) and then those high clouds reflecting the (IR) heat back to earth, and that's where the recent research about water vapor at high altitudes come in. But, then again, low cloud-covers also effectively traps the IR that is released by the ground at night? When climatologists speak of CO2 one easily get the impression that CO2 is the sole perpetrator of 'global warming', but that isn't the whole truth. CO2 is a 'forcing' meaning that it act as a catalyst, making it possible for a lot of other secondary mechanisms to heat up the atmosphere even further than the CO2 can do on its own.   

One major 'secondary effect' is water vapor. "This extra absorption within the atmosphere causes the air to warm just a bit more and the warmer the atmosphere the greater its capacity to hold more water vapor. This extra water vapor then further enhances the Earth’s greenhouse effect, far more even than the small warming forced by the added carbon dioxide. Scientists estimate that doubling levels of carbon dioxide in the atmosphere would be about the same as a 13 percent increase in water vapor, because water vapor is roughly eight times more effective than carbon dioxide as a greenhouse gas (Hartmann 1994).

In short, if water vapor is the 800-pound gorilla of the Earth’s greenhouse effect, then carbon dioxide is the steroid pill that helps water vapor lift temperatures even higher."

So then the question becomes, first, will there be more cloud covers if the humidity raise? And if it will, what kind of clouds can we expect? To predict the weather is extremely tricky, the Earth is a open ended non-linear system, open to space (end of atmosphere) that then becomes the last heat-regulator of Earth's climate. "All meteorological models inevitably fail at some point, due to the sheer complexity of the Earth’s system. In fact, chaos theory shows that weather will never be predictable with any significant accuracy for longer than 2 weeks, even with a nearly perfect model and nearly perfect input data." But we can use statistical data to predict the climate. The problem with that is how to find our historical data. When it comes to cloud covers it's more than tricky, Amy Clement, a climate scientist at the University of Miami used a combination of satellites and human observations " - literally, from sailors scanning the sky — that go back to 1952, and found the two sets were surprisingly in sync. "It's pretty remarkable," says Clement. "We were almost shocked by the degree of concordance."

The data showed that as the Pacific Ocean has warmed over the past several decades — part of the gradual process of global warming — low-level cloud cover has lessened. That might be due to the fact that as the earth's surface warms, the atmosphere becomes more unstable and draws up water vapor from low altitudes to form deep clouds high in the sky."

A Danish guy named Henrik Svensmark, a weather scientist at the Danish National Space Centre, proposed 2007 a mechanism in where Earth was experiencing a natural period of low cloud cover due to fewer cosmic rays entering the atmosphere. And therefore expected our human carbon dioxide emissions to have a much smaller impact on climate change, than what the mainstream climatologists was proposing. But the Max Planck Institute for Nuclear Physics have recently made a study of that proposition concluding that the could find no correlation between cosmic radiation and cloud covers. "Changes of cosmic rays caused by variations of the solar activity on time scales of a few days do not induce any changes of the global or regional cloud cover. This is concluded from a recent analysis performed by a Swiss-German collaboration. Thus, it is unlikely that cosmic rays influence climate. (Geophysical Research Letters 37, L03802, 03.02.2010)"

They "Swiss-German collaboration (scientists from the University of Bern, from EWAG and Frank Arnold from the Max Planck Institute for Nuclear Physics, MPIK) recently analyzed so-called Forbush decreases. These events, generated by sporadic solar eruptions, are characterized by a sudden decrease of the cosmic rays penetrating into the Earth's atmosphere, which recovers again within a few days. The decrease is similar in amplitude as at the maximum of the solar cycle. How can cosmic rays influence cloud formation? Clouds evolve from condensation nuclei which then grow to droplets. Such condensation nuclei are aerosol particles which in principle may also form from ions (electrically charged atoms or molecules). The ions in turn are produced by the cosmic rays from neutral air molecules.

The group around Frank Arnold has studied the formation of aerosol particles from ions by laboratory experiments. They found that the atmospheric ions grow preferably via uptake of gaseous sulfuric acid molecules. After sufficient growth, the ions may become stable but still very small aerosol particles. These may grow further, preferably by uptake of sulfuric acid. As demonstrated by MPIK laboratory measurements, gaseous sulfuric acid is formed in the atmosphere from sulfur dioxide, which stems mostly from fossil fuel combustion and volcanism. However, as revealed by aircraft-borne measurements made by MPIK in close collaboration with DLR (German Aerospace Center), sulfuric acid is formed in the atmosphere only rarely in sufficient amounts to allow the tiny aerosol particles to grow to the size of cloud condensation nuclei. Therefore, the limited supply of sulfur dioxide is a bottleneck of cosmic-ray mediated cloud formation.

So it seemed consequential to calculate the ion concentration in the atmosphere from measured data of the galactic cosmic radiation and to compare it with satellite data of cloud cover. As a result of the analysis of 6 pronounced Forbush events it can be stated, that the temporal changes of ion concentration and cloud cover are totally uncorrelated. For no cloud layer, the researchers of the Swiss-German collaboration could find global or regional effects, neither for a single event nor averaged over all 6 events. The scientists have only taken into account such Forbush decreases that were undisturbed by other effects. They calculated for all 6 events during each 20 days at every 3 hours the ion concentration in a 5°×5° grid over the globe and the entire troposphere. Then they compared these values with the also 3-hourly available satellite data of the cloud cover in 3 altitude layers. They evaluated only relative values to avoid possible systematic measurement errors to play a role. The method is sufficiently sensitive to detect effects on the scale postulated by the Danish scientists."

So it seems that the cosmic ray hypothesis isn't a answer. But what about the clouds we have?
And those we will get, as the climate warms up, and the humidity continues to raise? And what about the Amazons? I read a article in where they had found that it gave of a lot of particles, condensing humidity into clouds, but then at the same time, there seems to be more radiation given of, with less cloud covers reflecting IR? But also that there been two major droughts? Ah well, it's sure is a tricky bussiness. I know that the last years seen a lot of rain and clouds here in Sweden, with a lot of snow in the winter. Don't know if it has any importance on a long range scale though, but I personally find it as a 'sign of the times'. So, what do you think, will there be more clouds as the humidity raise, and what sort, what will the impact be?



Arbiters of Energy
Cloud cover unaffected by cosmic rays. 
In a Warming World, Cloudy Days Are a Boon.
Earth science data at NASA Langley Research Center
Papers on global cloud cover trends. (2009)
Drought in the Amazon.
 


 

Offline yor_on

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Humidity, CO2, and cloudcover. And cosmic rays ?
« Reply #1 on: 05/07/2011 16:42:59 »
What happens with water molecules when they move faster, I've seen some ideas where those molecules are expected to find it harder to coalesce and form clouds? We have some very hot areas meeting water like India, Thailand etc. Naively speaking now, they must have a high humidity, but, do they have more cloud covers? And when if so, relative the humidity (and season/temperature)?

"Smos is an experimental mission of the European Space Agency (ESA), and is providing some novel information to meteorologists, hydrologists and other scientists interested in how water moves around the globe. The 760km-high satellite carries an 8m-wide interferometric radiometer that senses the natural emission of microwaves coming up off the planet’s surface. Variations in the water content of soils will modify this signal." It was launched 2009.

Soils of UK and Europe drying out.

« Last Edit: 05/07/2011 16:47:30 by yor_on »
 

Offline frethack

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Humidity, CO2, and cloudcover. And cosmic rays ?
« Reply #2 on: 15/07/2011 17:46:23 »
Cloud microphysics is a very active area of current research.  Svensmarks work has problems, but I am very interested to see the results from his experiments at CERN.

What happens with water molecules when they move faster, I've seen some ideas where those molecules are expected to find it harder to coalesce and form clouds? We have some very hot areas meeting water like India, Thailand etc. Naively speaking now, they must have a high humidity, but, do they have more cloud covers? And when if so, relative the humidity (and season/temperature)?
Soils of UK and Europe drying out.

South/Southeast Asia have very heavy cloud cover and precipitation throughout the boreal summer monsoon months (the highest in the world), but there is more than just temperature and humidity involved.  Atmospheric pressure regimes, orographic effects (which prevent the monsoon from crossing north of the Himalayas), position of the ITCZ, etc. are all major factors...among others.

"Smos is an experimental mission of the European Space Agency (ESA), and is providing some novel information to meteorologists, hydrologists and other scientists interested in how water moves around the globe. The 760km-high satellite carries an 8m-wide interferometric radiometer that senses the natural emission of microwaves coming up off the planet’s surface. Variations in the water content of soils will modify this signal." It was launched 2009.

Soils of UK and Europe drying out.

Soils in the Southwest US are drying as well.  Im beginning a study now that is meant to quantify the feedback effects of soil moisture on drought severity.  Ill post some information as I get it.
 

Offline CliffordK

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Humidity, CO2, and cloudcover. And cosmic rays ?
« Reply #3 on: 16/07/2011 08:40:02 »
Water and clouds in the atmosphere are complicated....

Water exists in the atmosphere in all 3 phases, vapor, liquid, and solid.

Water vapor is essentially transparent to visible light, but has strong IR absorption bands.  Water droplets in clouds would also tend to be transparent, but they tend to diffuse and reflect the light due to refraction.  The same with crystals.   

The clouds tend to both reflect light back into space, and reflect IR back towards earth.  I.E. cool during the day and warm at night.

One other effect is what is called Latent Heat Flux.
When water evaporates, it takes energy from the body of water and transfers it to the water vapor, thus cooling the water at the surface.  Water molecules (H2O) (MW 18) are light molecules and tend to rise.  The upper atmosphere has a "cold trap" where the water tends to condense, and form clouds.  This condensation then transfers the energy from the vapor to the upper atmosphere.  The water then falls back to the surface as rain or snow to repeat the cycle.

Since the air density is not uniform, and CO2 (MW 44) is a heavy molecule, this is actually transferring energy from below the CO2 to above the majority of the CO2.

CO2 mediated heating is unlikely to break down the cold-trap for two reasons.
1) The decrease in temperature in the upper atmosphere is quite severe (not counting the thermosphere).
2) The CO2 theory is warming of the lower atmosphere by blocking IR emissions, and cooling of the upper atmosphere due to IR being blocked at lower altitudes. 

As air warms, its water carrying capacity increases which would likely mean more clouds and more rain.  Note that the arctic and antarctic are often very dry due to the low absolute humidity. 

One other thing to keep in mind.  Many forests tend to be dark in color, and thus would apparently have low albedo or reflectivity.  However, they actively participate in water transport, and both create clouds, and participate in Latent Heat Flux.  And, thus forests may be cooler than what albedo alone would predict.  Forests might be considered as Earth's natural air conditioner or climate mediator....  that is assuming we don't cut them all down.
 

Offline yor_on

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Humidity, CO2, and cloudcover. And cosmic rays ?
« Reply #4 on: 18/07/2011 03:14:17 »
Yep, well, it's been another rainy humid summer. Stating to feel almost British here :) Sometimes one wish one had a time machine, to see over a decade or two. But I think we are getting more precipitation than what is normal those last years, just as a guess. I haven't really checked that up.

And the seasons seems to come earlier too. Saw some studies made with bees on NASA in America finding that they are starting to pollinate earlier too. But this cloud business, and how it will work out for us should be a big divider for how the local 'climate', as for a country will shape up. Wish we had more weather satellites up there actually.
 

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Humidity, CO2, and cloudcover. And cosmic rays ?
« Reply #4 on: 18/07/2011 03:14:17 »

 

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