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breezy  
#321 Posted : 04 January 2011 20:38:14(UTC)
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So you want it both ways. Sensibly you see the smog in 1783 trapping heat, as we saw with smoke in Moscow last summer, but you deny it will trap heat or IR further up. And BTW, according to popular notions, Europe would get warmer winters and cooler summers after an eruption, so that doesn`t fit with the 1783/4 winter, which was a natural event, being the almost exact astronomical analogue as 1962/3 winter. You see, you have absolutely no way of discerning as to whether any  temp` drop is from "natural variation" or not.

Almost half of surface heating from the Sun is from IR, and I doubt what you say about so2 not absorbing it.

breezy  
#322 Posted : 04 January 2011 20:47:26(UTC)
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Originally Posted by: Stu N Go to Quoted Post

 

 

 

 A warming of the stratosphere is observed due to aerosols absorbing a bit of visible and (mainly terrestrial) IR.

 

 

So you`re saying the aerosols get heated by OLR but not incoming IR,  mmm !

Stu N  
#323 Posted : 04 January 2011 21:51:35(UTC)
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Originally Posted by: breezy Go to Quoted Post

So you want it both ways. Sensibly you see the smog in 1783 trapping heat, as we saw with smoke in Moscow last summer, but you deny it will trap heat or IR further up.

The nature of the aerosols differs according to altitude. The sulphur dioxide and, to a lesser extent, hydrogen sulphide emitted by volcanoes forms sulphuric acid. This chemical attracts water like nobody's business, but there isn't much of that available in the stratosphere so the aerosols are very small and very thinly spread out (Pinatubo emitted just ~20 megatonnes of sulphur dioxide, mostly into the stratosphere, compare with Laki's ~120 megatonnes, with plenty into the troposphere). So with Laki producing more tropospheric aerosol, with more H20 available to react with, the aerosols would have been bigger. Tropospheric and stratospheric aerosols have such different properties it's not valid to compare them like-for-like.

Also, the aerosol cloud cannot efficiently trap heat higher up because it's too diffuse. 20MT spread globally in the stratosphere again cannot be compared to a thick volcanic fog sitting over Europe for weeks on end.

I do not deny that the aerosol cloud warms, in fact I already noted that it does. Trouble is it warms the stratosphere, not the troposphere or surface (apart from the limited case of the polar night when it can conceivably have a measurable effect). See the paper I linked to on the previous page, it very clearly show stratospheric warming following the eruptions.

Originally Posted by: breezy Go to Quoted Post
And BTW, according to popular notions, Europe would get warmer winters and cooler summers after an eruption, so that doesn`t fit with the 1783/4 winter, which was a natural event, being the almost exact astronomical analogue as 1962/3 winter. You see, you have absolutely no way of discerning as to whether any  temp` drop is from "natural variation" or not.

Generally the thinking is volcanoes cause warming winters in Europe. I agree!

But: Warmer winters applies to tropical eruptions and usually not high latitude ones. The reason is fairly simple to explain, in that following a tropical eruption the stratospheric aerosol cloud tends to be thickest in the tropics (sorry for stating the obvious). As I mentioned above, the aerosol cloud warms the stratosphere. Also, due to the tropics having a greater availability of energy coming in and going out, this is where the stratosphere warms most.

This increases the equator to pole temperature gradient, and via thermal wind and all that the jet streams tend to strengthen in the 1 or 2 winters following a tropical eruption. Hence zonal flow and warmer than normal continental winters. This is also in the paper I linked to earlier. High latitude eruptions are not able to do this as effectively as the aerosol can't reach the equator in any great quantity (stratospheric meridional flow is slightly poleward).

But as I said more than once, Laki was not tropical and was not a typical explosive eruption. One thing you're right about is that you can't tell whether the winter would have been cold anyway.

Originally Posted by: breezy Go to Quoted Post

Almost half of surface heating from the Sun is from IR, and I doubt what you say about so2 not absorbing it.

(Quibble: the aerosols are little droplets of h2so4, sulphuric acid, not so2 which is a precursor chemical).

I realise I have been a bit sloppy, sorry. You are right about near IR, I had it stuck in my head that IR = longwave but this is not necessarily the case. I should have partitioned the spectrum into 'shortwave' and' longwave', the dividing line being 4 micons wavelength, because there is very little solar radiation longer and very little terrestrial radiation shorter. So here goes a hopefully clearer explanation:

Most solar IR is in the near IR, close to the visible spectrum. As you move away from the characteristic size of the aerosols, they interact less with the incoming radiation, but it does help warm it up and reduce the radiation received at the surface. This all counts as 'shortwave forcing' and affects incoming solar radiation. Consider this a correction to my previous post, replacing 'visible' with 'shortwave'.

You raised the possibility of a greenhouse like effect; because the aerosols are only in the stratosphere, the stratosphere warms up. But they don't interact that strongly with longwave so the longwave effect is much smaller than the shortwave effect (see, well, any of the literature to back this up).

Well, this has been a bit rambling. Dr. Alan Robock is his 2000 paper 'Volcanic Eruptions and Climate' explains it better than I (emphasis mine):

"Since the sulfate aerosol
particles are about the same size as visible light, with a
typical effective radius of 0.5 micrometres, but have a singlescatter
albedo of 1, they strongly interact with solar
radiation by scattering. Some of the light is backscattered,
reflecting sunlight back to space, increasing the
net planetary albedo and reducing the amount of solar
energy that reaches the Earth’s surface. This backscattering
is the dominant radiative effect at the surface and
results in a net cooling there
. Much of the solar radiation
is forward scattered, resulting in enhanced downward
diffuse radiation that somewhat compensates for a large
reduction in the direct solar beam."

What makes you think you know better than him? You are yet to actually present evidence of a lack of cooling after volcanic eruptions (the graph for Krakatoa did show cooling) and indeed are yet to provide a solid reason why there shouldn't be cooling. Is this left as an exercise for the reader?

 

SHOW EXTERNAL IMAGES

Edited by user 04 January 2011 22:20:10(UTC)  | Reason: Not specified

Offline Stephen Wilde  
#324 Posted : 04 January 2011 22:09:51(UTC)
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A pretty comprehensive overview from Stu there.

I tend to ignore volcanic effects so far as climate effects are concerned for the following reasons:

The effects are short lived, hardly ever more than 5 years. Better to regard them as affecting weather.

The effects are extremely variable depending not only on composition of the ejecta but also altitude and latitude. They can give cooling followed by warming or warming followed by cooling. Most often it is a net cooling because albedo (cooling) effects are generally greater than warming effects.

If forecasting short term or on a seasonal basis then yes volcanoes are important but not for longer unless someone can convincingly link levels of volcanic activity with cyclical solar or oceanic changes. Some are trying but I don't see it.

Stu N  
#325 Posted : 04 January 2011 22:18:51(UTC)
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Originally Posted by: Stephen Wilde Go to Quoted Post
A pretty comprehensive overview from Stu there.

I tend to ignore volcanic effects so far as climate effects are concerned for the following reasons:

The effects are short lived, hardly ever more than 5 years. Better to regard them as affecting weather.

The effects are extremely variable depending not only on composition of the ejecta but also altitude and latitude. They can give cooling followed by warming or warming followed by cooling. Most often it is a net cooling because albedo (cooling) effects are generally greater than warming effects.

If forecasting short term or on a seasonal basis then yes volcanoes are important but not for longer unless someone can convincingly link levels of volcanic activity with cyclical solar or oceanic changes. Some are trying but I don't see it.

While I wont discount longer term trends in volcanic activity being related to extraterrestrial effects, any link has to be tentatively made and well substantiated.

As for climate considerations: rare, massive eruptions (like the yellowstone caldera theory the discovery channel seemed so fond of a few years ago) definitely have the potential to alter global climate for a long time. So do massive asteroid strikes. Both pepper the earth on geological timescales, but for us right now? Interesting to investigate but useless to factor in. If they happen we're screwed anyway. That's not to say you shouldn't look at volcanoes at all. They're vital for climate change attribution studies and give their own clues as to climate sensitivity.

I'm just astonished that Breezy is arguing that eruptions don't cause cooling at the surface (globally averaged of course). Is he being contrary to the accepted science just for the sake of it?

Offline Stephen Wilde  
#326 Posted : 04 January 2011 22:42:59(UTC)
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"They're vital for climate change attribution studies and give their own clues as to climate sensitivity."

I agree with that but seem to come to a conclusion that some find inconvenient.

Basically the speed by which the normal run of volcanic activity is negated gives us a clue as to how well the system can also negate an attempt at climate disruption from any source.

The air circulation system just shifts a bit to provide a negative response that always seeks to restore the sea surface and surface air temperature equilibrium.

Hence my contention that any warming effect from extra CO2 is easily negated by an imperceptible shift in the air circulation systems with a consequent miniscule change in the speed of the water cycle.

So the climate response to any change that seeks to disturb the sea surface/surface air equilibrium is highly sensitive but because the response is always negative the outcome is an extremely stable and insensitive system overall.

That is why the oceans have remained liquid for billions of years despite huge volcanic disruption and catastrophic asteroid strikes. The system always bounced back in due course. Even a 30% increase in solar output has made little difference so a teensy bit of CO2 is likely a complete irrelevance.

Stu N  
#327 Posted : 04 January 2011 23:39:05(UTC)
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Originally Posted by: Stephen Wilde Go to Quoted Post


The air circulation system just shifts a bit to provide a negative response that always seeks to restore the sea surface and surface air temperature equilibrium.

Yes the circulation shifts but it's heading towards a new, colder equilibrium (hence the cooling!)*. This is not an example of an enhanced homeostasis of the Earth system. Studies have shown water vapour feedback is positive following eruptions (i.e. enhances cooling). The climate goes back to normal simply because the aerosols are gone within a few years. It's not evidence that a radiative forcing can't change the climate; estimates of sensitivity from volcanic activity are highly dependent upon the lag used (or time constant, to give the proper name), but do not disagree with estimates from other sources.

However these considerations aren't helped by the fact that volcanic forcings following an eruption change rapidly both temporally and spatially.

* PS. so how does this give evidence that we're currently not heading towards a new, warmer equilibrium?

Edited by user 04 January 2011 23:42:01(UTC)  | Reason: Not specified

Offline Stephen Wilde  
#328 Posted : 05 January 2011 09:32:46(UTC)
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If a volcano causes warming of the air the system will shift to cooling of the air in order to try to restore the sea surface/surface air temperature equilibrium. If it causes cooling of the air the system will shift to a warming response in the air for the same reason.

Increased/decreased water vapour feedback is part of the system response and demonstrates a faster/slower water cycle. So if the initial volcanic effect is warming of the air alone to cause increased evaporation from the oceans then the water cycle ramps up with increased cloud and higher albedo so that the response overshoots a bit before stabilising later.

However the precise scale and the sign of the response is variable depending on the characteristics of each eruption and the response changes quiokly over time.

The underlying temperature equilibrium is set by pressure and density differentials at the ocean surface. The temperature at which equilibrium is achieved will only change if the temperature of the oceans is changed. A change in air temperature alone is not enough because the ocean dominates. Water warms air but air will not warm water. Warmer air just changes the speed of the water cycle without changing the equilibrium temperature. Warmer water will change the equilibrium temperature.

That is why I regard the IR issue that we discussed previously so important.

So if GHG warming is limited to the air the equilibrium temperature of sea and air combined does not change. All one sees is a faster water cycle.





Edited by user 05 January 2011 13:31:59(UTC)  | Reason: Not specified

breezy  
#329 Posted : 06 January 2011 02:08:01(UTC)
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Originally Posted by: Stu N Go to Quoted Post

1) Also, the aerosol cloud cannot efficiently trap heat higher up because it's too diffuse. 20MT spread globally in the stratosphere again cannot be compared to a thick volcanic fog sitting over Europe for weeks on end.

2) I do not deny that the aerosol cloud warms, in fact I already noted that it does. Trouble is it warms the stratosphere, not the troposphere or surface (apart from the limited case of the polar night when it can conceivably have a measurable effect). See the paper I linked to on the previous page, it very clearly show stratospheric warming following the eruptions.

---------------------------------------------------------------------------------------------------------------------

 

 You are yet to actually present evidence of a lack of cooling after volcanic eruptions (the graph for Krakatoa did show cooling) and indeed are yet to provide a solid reason why there shouldn't be cooling. Is this left as an exercise for the reader?

There are contradictions there regarding what you say about the stratosphere and troposphere.

The temperature graph for Krakatoa showed 3 months cooling then warming then cooling, there is no way you can say beyond doubt that any of this was forced by the volcano. I do need to show why there is no cooling, just that there is no significant cooling is sufficient. It`s not as if you have presented any conclusive evidence of cooling after eruptions. Like I said before, I am more interested in the cooling and then warming leading up to the events that actually set them off !

 

 

FredBear  
#330 Posted : 06 January 2011 07:24:51(UTC)
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As someone who has watched the satellite records for 10+ years I find it amazing that the tiny(?) change in temperature of the earth's surface can produce such a big change in the arctic ice. One factor that leads me to believe in GHG warming is that it was predicted that it would occur in the 19th century, long before global temperature could be monitored as it is now. Subsequently, it has been calculated that the effects of GHG warming would be greatest towards the poles - and we have seen a decline in sea-ice area/volume in the Arctic. (However sea-ice area in the Antarctic tends to show a slight increase so far, even if ice shelves have collapsed and temperatures increased in some areas! - maybe ice volume is going down!?). Fickle weather dictates what we can do day to day, but it is climate that provides our basic living conditions.

However, it would appear to me that the driver of weather is the energy (heat) stored in water - as clearly seen in cyclones in tropical areas. It can still be seen in cold areas (eg.in lake-effect snow in North America), where it is the wind that strips the water vapour out to cool the water, the water-vapour then condensing to release latent heat to the air. GHG warming can only affect the long wavelength IR radiation from the water and earth's surface and to a lesser extent that from the air (since the bulk of it will be colder than the surfaces beneath) and the same incoming radiation in sunlight.

The slightly warmer air will tend not to cool the underlying water so much, allowing currents, such as the Gulf Steam, to maintain higher temperatures to more northerly latitudes. (But surely any increase in wind velocity/storms would quickly negate this effect?).

Therefore I see there are 3 factors increasing the melting of polar ice:-

a)   Warmer water melting it from below.

b)   Warmer air melting it from above.

c)   Decreased albedo from reduced ice cover feeding back into a) above.

The complicating factors include:-

1)   What changes will occur in cloud/mist/fog/aerosol cover - affecting albedo?

2)   What changes will occur in wind speed/direction - affecting melting, storms -> ice compaction/breakup?

3)   What changes will occur in currents - affecting heat transport, ice transport?

I believe that there is a valid concern that human activities can affect global temperatures and that it is right to be cautious about continuing to rely on growth (or even business as usual) to maintain living standards. In the UK we have seen the squandering of North Sea oil at cheap prices, until we have ended up as an importer at high prices with no security of supply, which is where we were before the oil was discovered! We cannot afford to do the same with the global climate - there is no cheap way back if we foul things up.

Mike

User is suspended until 31/01/2293 12:26:49(UTC) Gray-Wolf  
#331 Posted : 06 January 2011 09:31:59(UTC)
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http://nsidc.org/arcticseaicenews/

Above is the Dec report for the Arctic and it makes plain the even the weather patterns that used to favour ice growth/retention now destroy ice (as we saw with the 'plume' of Paleocrystic in south Beaufort last summer.

Insofar as 'global temps' go how much do the 30c positive anoms over autumn (open water at 0c instead of ice with -30c above) impact temps? Last summer saw many of the sea areas clear of ice allowing the 24hr sun to warm the waters. Come autumn this heat has to go somewhere before the water can freeze so we delay when 'freeze' can occur leading to 'odd' weather around the N .Hemisphere. In time the 'anom' will cover the whole basin and 'cold' may not arrive in the Arctic until Dec leaving us with permanent 'Indian Summers' (and not the 'polar plunges' we have now with only 'sections' of the Basin 'hot' allowing the normal cold air to amass before being displaced south....to us!)

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Offline polarwind  
#332 Posted : 06 January 2011 10:09:07(UTC)
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Originally Posted by: FredBear Go to Quoted Post

As someone who has watched the satellite records for 10+ years I find it amazing that the tiny(?) change in temperature of the earth's surface can produce such a big change in the arctic ice. One factor that leads me to believe in GHG warming is that it was predicted that it would occur in the 19th century, long before global temperature could be monitored as it is now. Subsequently, it has been calculated that the effects of GHG warming would be greatest towards the poles - and we have seen a decline in sea-ice area/volume in the Arctic. (However sea-ice area in the Antarctic tends to show a slight increase so far, even if ice shelves have collapsed and temperatures increased in some areas! - maybe ice volume is going down!?). Fickle weather dictates what we can do day to day, but it is climate that provides our basic living conditions.

However, it would appear to me that the driver of weather is the energy (heat) stored in water - as clearly seen in cyclones in tropical areas. It can still be seen in cold areas (eg.in lake-effect snow in North America), where it is the wind that strips the water vapour out to cool the water, the water-vapour then condensing to release latent heat to the air. GHG warming can only affect the long wavelength IR radiation from the water and earth's surface and to a lesser extent that from the air (since the bulk of it will be colder than the surfaces beneath) and the same incoming radiation in sunlight.

The slightly warmer air will tend not to cool the underlying water so much, allowing currents, such as the Gulf Steam, to maintain higher temperatures to more northerly latitudes. (But surely any increase in wind velocity/storms would quickly negate this effect?).

Therefore I see there are 3 factors increasing the melting of polar ice:-

a)   Warmer water melting it from below.

b)   Warmer air melting it from above.

c)   Decreased albedo from reduced ice cover feeding back into a) above.

The complicating factors include:-

1)   What changes will occur in cloud/mist/fog/aerosol cover - affecting albedo?

2)   What changes will occur in wind speed/direction - affecting melting, storms -> ice compaction/breakup?

3)   What changes will occur in currents - affecting heat transport, ice transport?

I believe that there is a valid concern that human activities can affect global temperatures and that it is right to be cautious about continuing to rely on growth (or even business as usual) to maintain living standards. In the UK we have seen the squandering of North Sea oil at cheap prices, until we have ended up as an importer at high prices with no security of supply, which is where we were before the oil was discovered! We cannot afford to do the same with the global climate - there is no cheap way back if we foul things up.

Mike

Greetings FredBear - welcome to TWO.

What I find interesting about your post is that it is holistic in approach. This is something imo, that is not considered enough in many contributions in the climate forum

Do you have any comments about the holistic approach and content in this link? -

http://www.nytimes.com/2...pinion/26cohen.html?_r=2

"The professional standards of science must impose a framework of discipline and at the same time encourage rebellion against it". – Michael Polyani (1962)

"If climate science is sound and accurate, then it should be able to respond effectively to all the points raised…." - Grandad

"The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts". - Bertrand Russell

"Science is the belief in the ignorance of the experts" – Richard Feynman

"A consensus means that everyone agrees to say collectively what no one believes individually.”- Abba Eban, Israeli diplomat

Dave,Derby

FredBear  
#333 Posted : 06 January 2011 13:26:29(UTC)
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Afraid the link

( http://www.nytimes.com/2...pinion/26cohen.html?_r=2 )

in post 332 above does not connect anymore.

Offline polarwind  
#334 Posted : 06 January 2011 13:45:13(UTC)
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Originally Posted by: FredBear Go to Quoted Post
Afraid the link

( http://www.nytimes.com/2...pinion/26cohen.html?_r=2" href="http://www.nytimes.com/2...pinion/26cohen.html?_r=2">http://www.nytimes.com/2...pinion/26cohen.html?_r=2 )

in post 332 above does not connect anymore.

Try this -

http://www.nytimes.com/2010/12/26/opinion/26cohen.html?_r=3

Here is relevent part -

Annual cycles like El Niño/Southern Oscillation, solar variability and global ocean currents cannot account for recent winter cooling. And though it is well documented that the earth’s frozen areas are in retreat, evidence of thinning Arctic sea ice does not explain why the world’s major cities are having colder winters.

But one phenomenon that may be significant is the way in which seasonal snow cover has continued to increase even as other frozen areas are shrinking. In the past two decades, snow cover has expanded across the high latitudes of the Northern Hemisphere, especially in Siberia, just north of a series of exceptionally high mountain ranges, including the Himalayas, the Tien Shan and the Altai.

The high topography of Asia influences the atmosphere in profound ways. The jet stream, a river of fast-flowing air five to seven miles above sea level, bends around Asia’s mountains in a wavelike pattern, much as water in a stream flows around a rock or boulder. The energy from these atmospheric waves, like the energy from a sound wave, propagates both horizontally and vertically.

As global temperatures have warmed and as Arctic sea ice has melted over the past two and a half decades, more moisture has become available to fall as snow over the continents. So the snow cover across Siberia in the fall has steadily increased.

The sun’s energy reflects off the bright white snow and escapes back out to space. As a result, the temperature cools. When snow cover is more abundant in Siberia, it creates an unusually large dome of cold air next to the mountains, and this amplifies the standing waves in the atmosphere, just as a bigger rock in a stream increases the size of the waves of water flowing by.

The increased wave energy in the air spreads both horizontally, around the Northern Hemisphere, and vertically, up into the stratosphere and down toward the earth’s surface. In response, the jet stream, instead of flowing predominantly west to east as usual, meanders more north and south. In winter, this change in flow sends warm air north from the subtropical oceans into Alaska and Greenland, but it also pushes cold air south from the Arctic on the east side of the Rockies. Meanwhile, across Eurasia, cold air from Siberia spills south into East Asia and even southwestward into Europe.

Edited by user 06 January 2011 13:52:58(UTC)  | Reason: relevent part added - trouble with link

"The professional standards of science must impose a framework of discipline and at the same time encourage rebellion against it". – Michael Polyani (1962)

"If climate science is sound and accurate, then it should be able to respond effectively to all the points raised…." - Grandad

"The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts". - Bertrand Russell

"Science is the belief in the ignorance of the experts" – Richard Feynman

"A consensus means that everyone agrees to say collectively what no one believes individually.”- Abba Eban, Israeli diplomat

Dave,Derby

FredBear  
#335 Posted : 06 January 2011 17:01:30(UTC)
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Polarwind,

I used to watch the Canadian "Global sea surface anomaly and snow cover" maps, eg:-

http://www.weatheroffice.gc.ca/saisons/image_e.html?img=2010122500_054_G6_global_I_SEASON_tm@lg@sd_000&title=daily

comparing them for different years by eye, but glitches in viewing and the excellent polar ice mapping encouraged me to refocus on those.

I am not suprised to hear that Siberia has more snow in recent years - with the arctic seas unfrozen any northern plunge of air is likely to produce the equivalent of the Great Lakes "lake effect snow". Once snow is down it traps residual heat in the ground, and the air above cools even more rapidly if there is a lack of cloud cover (This occurred in the more northern parts of the UK this winter, giving record lows.) And of course any extra heat in the ground will encourage a faster thaw in spring.

From what I have seen this year, blocking highs around Britain have diverted the jet stream southwards in the North Atlantic, and our usual dose of warm air has passed up Eastern Canada and Greenland (It would be interesting to know how much more snow has fallen this winter at higher levels of Greenland while the lower levels were catching the unseasonal warmth!).

If I remember correctly, at one time the BBC weather forcasts used to show the position of the jet stream, and these showed a marked difference in temperature between London (to the north) and Paris to the south. Mentally I was always trying to push the jet stream north to get "better" weather!

As for the jet stream, when it meanders southwards it drags cold air from the north and east over Western Europe, and we wonder what has happened to global warming!

Mike

Offline Devonian  
#336 Posted : 06 January 2011 17:03:50(UTC)
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Originally Posted by: FredBear Go to Quoted Post

Polarwind,

I used to watch the Canadian "Global sea surface anomaly and snow cover" maps, eg:-

http://www.weatheroffice.gc.ca/saisons/image_e.html?img=2010122500_054_G6_global_I_SEASON_tm@lg@sd_000&title=daily

comparing them for different years by eye, but glitches in viewing and the excellent polar ice mapping encouraged me to refocus on those.

I am not suprised to hear that Siberia has more snow in recent years - with the arctic seas unfrozen any northern plunge of air is likely to produce the equivalent of the Great Lakes "lake effect snow". Once snow is down it traps residual heat in the ground, and the air above cools even more rapidly if there is a lack of cloud cover (This occurred in the more northern parts of the UK this winter, giving record lows.) And of course any extra heat in the ground will encourage a faster thaw in spring.

From what I have seen this year, blocking highs around Britain have diverted the jet stream southwards in the North Atlantic, and our usual dose of warm air has passed up Eastern Canada and Greenland (It would be interesting to know how much more snow has fallen this winter at higher levels of Greenland while the lower levels were catching the unseasonal warmth!).

If I remember correctly, at one time the BBC weather forcasts used to show the position of the jet stream, and these showed a marked difference in temperature between London (to the north) and Paris to the south. Mentally I was always trying to push the jet stream north to get "better" weather!

As for the jet stream, when it meanders southwards it drags cold air from the north and east over Western Europe, and we wonder what has happened to global warming!

Mike

Eminently sensible stuff

SHOW EXTERNAL IMAGES

"When it takes nearly 900,000 votes to elect one party’s MP, and just 26,000 for another, you know something is deeply wrong."

The electoral reform society, 14,12,19

Offline polarwind  
#337 Posted : 06 January 2011 17:42:01(UTC)
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Originally Posted by: Devonian Go to Quoted Post

Originally Posted by: FredBear Go to Quoted Post

Polarwind,

I used to watch the Canadian "Global sea surface anomaly and snow cover" maps, eg:-

http://www.weatheroffice...54_G6_global_I_SEASON_tm@lg@sd_000&title=daily" href="http://www.weatheroffice.gc.ca/saisons/image_e.html?img=2010122500_054_G6_global_I_SEASON_tm@lg@sd_000&title=daily">http://www.weatheroffice.gc.ca/saisons/image_e.html?img=2010122500_054_G6_global_I_SEASON_tm@lg@sd_000&title=daily

comparing them for different years by eye, but glitches in viewing and the excellent polar ice mapping encouraged me to refocus on those.

I am not suprised to hear that Siberia has more snow in recent years - with the arctic seas unfrozen any northern plunge of air is likely to produce the equivalent of the Great Lakes "lake effect snow". Once snow is down it traps residual heat in the ground, and the air above cools even more rapidly if there is a lack of cloud cover (This occurred in the more northern parts of the UK this winter, giving record lows.) And of course any extra heat in the ground will encourage a faster thaw in spring.

From what I have seen this year, blocking highs around Britain have diverted the jet stream southwards in the North Atlantic, and our usual dose of warm air has passed up Eastern Canada and Greenland (It would be interesting to know how much more snow has fallen this winter at higher levels of Greenland while the lower levels were catching the unseasonal warmth!).

If I remember correctly, at one time the BBC weather forcasts used to show the position of the jet stream, and these showed a marked difference in temperature between London (to the north) and Paris to the south. Mentally I was always trying to push the jet stream north to get "better" weather!

As for the jet stream, when it meanders southwards it drags cold air from the north and east over Western Europe, and we wonder what has happened to global warming!

Mike

Eminently sensible stuff

Yep, I look forward to further contributions

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Stu N  
#338 Posted : 08 January 2011 01:42:18(UTC)
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Originally Posted by: Stephen Wilde Go to Quoted Post


That is why I regard the IR issue that we discussed previously so important.

Hi Stephen

I have just spotted that the highly technical blog 'Scienceofdoom' has a (so far) 4-part series on this exact topic:

http://scienceofdoom.com/2010/10/06/does-back-radiation-heat-the-ocean-part-one/

 

I am yet to read any of it; I thought the two of us should have a look, take a while to understand what's being said, and then comment here in a few days. As yet I have no idea whether SoD has unearthed evidence for either of our viewpoints, but what can be sure is that SoD will have unearthed evidence for something, and it will be fully referenced and very comprehensive.

All posts on that site come with a high recommendation from me!

Offline Stephen Wilde  
#339 Posted : 08 January 2011 08:48:28(UTC)
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Posts: 3,266

Thanks Stu, I've joined in the comments with this question:

"Part Two doesn’t seem to deal with evaporation at all, merely radiation, convection and conduction.

How then can it be said to deal adequately with Hypothesis A ?"

Hypothesis A is the one that suggests that all the DLR (Downward Longwave Radiation) gets converted to latent energy.He thinks the ocean would feeze if that were the case but I have dealt with that elsewhere by pointing out that the latent heat required is taken from where it is most readily available so that the ocean surface does not get any colder trhan the air above it.

Nor does he mention anywhere the implications of the 0.3C cooler layer across all the ocean surfaces which is itself evidence in support of hypothesis A.

User is suspended until 31/01/2293 12:26:49(UTC) Gray-Wolf  
#340 Posted : 13 January 2011 18:19:13(UTC)
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