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Post by murf26 on Oct 14, 2009 12:05:45 GMT
I'm not a scientist, just a guy who has a few questions about the stratosphere:
*How long would it take to cool the Earth's stratosphere to the point that we would reach a Maunder-type minimum?
*Does the lack of sunspots/solar activity affect the stratospheric temp?
*If we are in a "minimum", how long would it take the stratosphere to warm up to take us out of the "minimum"?
Again, I apologize for any repeated questions from other posts...
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Post by poitsplace on Oct 15, 2009 4:33:21 GMT
Its pretty much there already. The outer atmosphere (not the stratosphere) shrank too. It happens quickly because most of the energy responsible for stratospheric warming comes directly from the sun's UV. Less UV, less warming.
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wylie
Level 3 Rank
Posts: 129
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Post by wylie on Oct 17, 2009 2:22:21 GMT
Murf,
There is a strong relationship between the amount of Ozone formation in the stratosphere and the mid to far UV light (around 250-300nm) that is incident on the Earth. Those wavelengths are MUCH more dependent on the Solar cycle than the total radiative output. For example, while the total amount of the sun's output will only vary by about 0.1% from peak to trough of the solar cycle, the output at those short UV wavelengths varies by as much 10% (100 times more). This is because those wavelengths are only produced by the acceleration of plasma energy that accompanies the extreme magnetic fields in sunspots. SO, when sunspot activity is high (the peak of the solar cycle) there is abundant formation of ozone (O3) in the stratosphere. Of course, the opposite occurs at solar minimum. The solar minimum is about as low as it gets right now, so the ozone concentration in the stratosphere is near minimum.
All this matters a LOT because the stratosphere is not directly warmed much by any other mechanism. The troposphere and its HUGE flux of heat generated by the water cycle is below the stratosphere. It is the DIRECT heating of the stratosphere by absorption of far UV light (to create ozone) and absorption of MID-UV light (to heat ozone). Of course, without that ozone, we would have a LOT more Mid UV light impinging on the earth's surface, so it is a good thing that the formation of ozone occurs (some might think it more than fortunate - perhaps even PLANNED).
So the direct heating of the stratosphere follows a closer correlation to the solar cycle than the surface temperature. Other correlations between ozone heating in the stratosphere and surface temperatures are much less certain (perhaps even speculative), although some recent data seems to show a cloud formation correlation with the solar cycle (not so clear).
HOpe that this helps you.
Ian
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Post by glc on Oct 17, 2009 17:30:45 GMT
So the direct heating of the stratosphere follows a closer correlation to the solar cycle than the surface temperature
Ian
Bearing in mind, your earlier comments about the relatively large change in UV output over the solar cycle might we expect any cooling related to solar activity to be more immediately obvious in the stratosphere.
There is, of course, the expected stratospheric cooling from the increase in ghgs which does confuse the situation somewhat but, as far as the stratosphere is concerned, the 2 forcings (solar + ghg) should be pulling in the same direction (i.e. cooling).
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Post by radiant on Oct 17, 2009 18:11:25 GMT
So the direct heating of the stratosphere follows a closer correlation to the solar cycle than the surface temperatureIan Bearing in mind, your earlier comments about the relatively large change in UV output over the solar cycle might we expect any cooling related to solar activity to be more immediately obvious in the stratosphere. There is, of course, the expected stratospheric cooling from the increase in ghgs which does confuse the situation somewhat but, as far as the stratosphere is concerned, the 2 forcings (solar + ghg) should be pulling in the same direction (i.e. cooling). None of the greenhouse gases can penetrate more than a tiny distance into the freezing cold water containing trophosphere where absorptions will send the full spectrum of waters frequencies upwards and downwards equally. All of waters downwards frequencies will be absorbed in a tiny distance to be emitted upwards and downwards. The area is already freezing cold. The distances are so tiny that it can have no influence whatsoever to the lower atmospheres temperatures.
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Post by magellan on Oct 17, 2009 19:25:20 GMT
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Post by glc on Oct 18, 2009 0:16:18 GMT
None of the greenhouse gases can penetrate more than a tiny distance into the freezing cold water containing trophosphere where absorptions will send the full spectrum of waters frequencies upwards and downwards equally. All of waters downwards frequencies will be absorbed in a tiny distance to be emitted upwards and downwards. The area is already freezing cold.
I'm not sure this has any relevance to my question.
I don't believe Magellan's plot does either - apart, that is, from showing that there has been no stratospheric cooling in the past few years.
Let's try again:
If the current low solar activity (and the associated drop in UV output) really is a significant driver in the earth's climate shouldn't it be evident in the stratospheric temperatures, i.e. shouldn't the stratosphere be cooling?
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Post by sigurdur on Oct 18, 2009 0:34:47 GMT
None of the greenhouse gases can penetrate more than a tiny distance into the freezing cold water containing trophosphere where absorptions will send the full spectrum of waters frequencies upwards and downwards equally. All of waters downwards frequencies will be absorbed in a tiny distance to be emitted upwards and downwards. The area is already freezing cold.I'm not sure this has any relevance to my question. I don't believe Magellan's plot does either - apart, that is, from showing that there has been no stratospheric cooling in the past few years. Let's try again: If the current low solar activity (and the associated drop in UV output) really is a significant driver in the earth's climate shouldn't it be evident in the stratospheric temperatures, i.e. shouldn't the stratosphere be cooling? Not quite yet from what I have read. Wait for another 3-4 years and you will see the influence from the drop in UV and the low solar activity. Just as the increased solar output in the late 60's didn't show up till the mid 70's.
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Post by socold on Oct 18, 2009 1:14:10 GMT
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Post by radiant on Oct 18, 2009 4:23:37 GMT
None of the greenhouse gases can penetrate more than a tiny distance into the freezing cold water containing trophosphere where absorptions will send the full spectrum of waters frequencies upwards and downwards equally. All of waters downwards frequencies will be absorbed in a tiny distance to be emitted upwards and downwards. The area is already freezing cold.I'm not sure this has any relevance to my question. I don't believe Magellan's plot does either - apart, that is, from showing that there has been no stratospheric cooling in the past few years. Let's try again: If the current low solar activity (and the associated drop in UV output) really is a significant driver in the earth's climate shouldn't it be evident in the stratospheric temperatures, i.e. shouldn't the stratosphere be cooling? 1. Water vapour is present in the stratosphere in significant quantities. If the surface warms then more water will be present in the stratosphere which will cool the stratosphere. The surface of the earth has been cooling for a few years now so less water will be present in the stratosphere which might warm the stratosphere 2. Methane oxidises in the stratosphere to produce water. 3. I am totally unable to predict what will happen when significant factors like change of UV or other factors happen. 4. Climate varies 5. Stratospheric temperatures could randomly vary just as the temperature on earth randomly varies 6. There is so much water vapour in the stratosphere and atmosphere generally that it is more or less impossible for any other gas to have much impact upon the climate of earth when even low band IR radiation above 1.8 micrometer and all of the other bands of IR can be entirely absorbed in only 1mm of precipital water vapour and surprisingly due to the incredible absorptive power of water even stratospheric water vapour content is significant. 7. Water vapour in the atmosphere may warm the upper atmosphere when UV is intense. 8. Methane reacts to produce water in the atmosphere when UV is intense 9. Water vapour may fall when UV is not intense 10 Changes in water vapour content in the stratosphere are likely to have significant changes to atmospheric chemistry as for example the rate of creation of ozone falls if water is present. 10. Only experimentation can reveal what is happening
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Post by glc on Oct 18, 2009 8:21:35 GMT
1. Water vapour is present in the stratosphere in significant quantities.
What do you mean by "significant quantities"? The earth's stratosphere is, to all intents and purposes, 'dry'.
If the surface warms then more water will be present in the stratosphere which will cool the stratosphere
It depends on what is causing the warming. If it is due to ghgs then the stratosphere should cool. If, on the other hand, it is due to increased solar output then the stratosphere should warm.
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Post by glc on Oct 18, 2009 8:30:49 GMT
Not quite yet from what I have read. Wait for another 3-4 years and you will see the influence from the drop in UV and the low solar activity.
Just as the increased solar output in the late 60's didn't show up till the mid 70's.
What "increased solar output in the late 60's"? Solar Cycle 20 was the weakest cycle in the second half of the 20th century. SC20 began in 1964 and ended in ~1976. Throughout that period global temperatures remained more or less flat.
It's rather a problem for the solar theorists. Almost as soon as SC20 ended the late 20th century warming began. Yet throughout the strongest cycle ever recorded (i.e. SC 19) global temperatures were falling.
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Post by poitsplace on Oct 18, 2009 9:24:54 GMT
1. Water vapour is present in the stratosphere in significant quantities. What do you mean by "significant quantities"? The earth's stratosphere is, to all intents and purposes, 'dry'. Yeah, I've got to agree on that. The stratosphere is above the tropopause and has little mixing. All the water vapor (that can by 220k) gets checked at the "door" and from then on there's warming with no increase in water vapor. So it's not JUST as dry as 220k air, the relative humidity (which makes no difference in this discussion except for control of lapse rate) keeps going down while temperature soars to...what? 60C? 70C?
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Post by radiant on Oct 18, 2009 9:39:56 GMT
1. Water vapour is present in the stratosphere in significant quantities. What do you mean by "significant quantities"? The earth's stratosphere is, to all intents and purposes, 'dry'. If the surface warms then more water will be present in the stratosphere which will cool the stratosphereIt depends on what is causing the warming. If it is due to ghgs then the stratosphere should cool. If, on the other hand, it is due to increased solar output then the stratosphere should warm. You need to do your own reading on water in the stratosphere and find that there is significant quantities there. The significance comes from the astonishing ability of water to absorb radiation and enable stratospheric chemistry. I see also that Steve felt that 2 inches of water was not significant, whereas in fact all of outgoing emissions of significance are absorbed in 0.01mm of water. Most of us are lacking knowledge about water which is one of the reasons why the American Chemical Society sent letters of outrage to the editor of their journal who was promoting unproven ideas about the atmosphere. Lief Svaalgaard will tell you that solar output is essentially constant. As higher frequencies are observed to fall low band frequencies increase. Magnetic influences might be capable of altering chemistry since solar flares are observed to change the chemistry. Humans dont know much about their world at this point in time. Solar output is almost totally absorbed in the furthest UV area and is very significantly absorbed in the IR band also. If one falls and one rises the result will be no difference.
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Post by radiant on Oct 18, 2009 10:14:16 GMT
1. Water vapour is present in the stratosphere in significant quantities. What do you mean by "significant quantities"? The earth's stratosphere is, to all intents and purposes, 'dry'. Yeah, I've got to agree on that. The stratosphere is above the tropopause and has little mixing. All the water vapor (that can by 220k) gets checked at the "door" and from then on there's warming with no increase in water vapor. So it's not JUST as dry as 220k air, the relative humidity (which makes no difference in this discussion except for control of lapse rate) keeps going down while temperature soars to...what? 60C? 70C? pubs.giss.nasa.gov/abstracts/2001/Shindell.htmlwww.agu.org/sci_soc/mockler.html#mockler1Water in the stratosphere is being studied as is the circulation of water[/color] from the stratosphere into the mesosphere. mls.jpl.nasa.gov/joe/Pumphrey_1997.pdfClearly the upper mesosphere is wetter in summer than in winter" The general circulation in the mésosphère is from summer pole to winter pole, with upwelling at the summer pole and downwelling at the winter one. "
"Water is transported partly by this circulation and partly by turbulent diffusion"
"We can therefore infer that unusually wet air has arrived there recently from below"
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