After listening to Carole Kirkwood talking about what a wet and cold summer its been over Scotland this year on this mornings Breakfast Weather, it does seem to me that as far as the media are concerned most of today's weather woes in this country today, including this one can be blamed on the jet stream, or lack of jet stream, or the position of the jet stream. So if the answer to most of the world's climate problems is the ubiquitous "jet stream", what about its part in global warming? I haven't seen any research that looks into the role jet streams play in global warming, but I'm sure it won't be long before there is a slew of scientific papers about it.

If this is true, just what controls the position and strength of the jet stream, and the answer to that must be the general atmospheric circulation, but of course that's not half as catchy, dynamic or sexy as the phrase "jet stream". I just can't imagine John Hammond for instance spending an hour in a BBC Horizon program to explain the intricacies of the Hadley cell and the northeast trade winds, when he can talk over a 3D animation and fly through of a North Atlantic super jet blowing at 250 knots.

I'm sure that the phrase "jet stream" will be cropping in many conversations about the weather in the coming years, you can easily picture one old dear saying to another in a bus queue "I know Enid the weather has been simply terrible, and you know it's all down to the orientation of the Jet stream over Iceland you know".

https://xmetman.wordpress.com/
http://xmetman.com/

On Tue, 11 Aug 2015 02:35:01 -0700 (PDT)
xmetman wrote:

After listening to Carole Kirkwood talking about what a wet and cold
summer its been over Scotland this year on this mornings Breakfast
Weather, it does seem to me that as far as the media are concerned
most of today's weather woes in this country today, including this
one can be blamed on the jet stream, or lack of jet stream, or the
position of the jet stream. So if the answer to most of the world's
climate problems is the ubiquitous "jet stream", what about its part
in global warming? I haven't seen any research that looks into the
role jet streams play in global warming, but I'm sure it won't be
long before there is a slew of scientific papers about it.

There have been several suggestions that the differential warming of
the Arctic and the Tropics will weaken the Jet Stream due to a
reduction in thermal contrast. This weakening of the Jet would then
lead to large meanders in the Stream and long spells of severe
weather, either cold or hot. This idea seems to have been accepted
though it bothered me a bit when I actually started to think about it.

I recall being taught (which I accept does not necessarily mean I was
taught) that slow-moving or stationary upper waves are associated with
a strong Jet; small, transitory waves are associated with weak Jet
Streams.

Then I found an article by CEP Brooks in an online 1950 issue of
Weather which said more or less the same thing. It also said that
they'd expected a weakening of upper winds due to the differential
warming that had occurred before WWII and had been surprised to find
that they'd strengthened instead.


If this is true, just what controls the position and strength of the
jet stream, and the answer to that must be the general atmospheric
circulation, but of course that's not half as catchy, dynamic or sexy
as the phrase "jet stream".

One thing that has an effect on the atmospheric circulation, as I've
said before, is the pattern of SST anomalies, particularly in the Grand
Banks region.


--
Graham P Davis, Bracknell, Berks. [Retd meteorologist/programmer]
http://www.scarlet-jade.com/
I wear the cheese. It does not wear me.
Posted with Claws: http://www.claws-mail.org/

On Tuesday, August 11, 2015 at 11:46:00 AM UTC+1, Graham P Davis wrote:
On Tue, 11 Aug 2015 02:35:01 -0700 (PDT)
xmetman wrote:

After listening to Carole Kirkwood talking about what a wet and cold
summer its been over Scotland this year on this mornings Breakfast
Weather, it does seem to me that as far as the media are concerned
most of today's weather woes in this country today, including this
one can be blamed on the jet stream, or lack of jet stream, or the
position of the jet stream. So if the answer to most of the world's
climate problems is the ubiquitous "jet stream", what about its part
in global warming? I haven't seen any research that looks into the
role jet streams play in global warming, but I'm sure it won't be
long before there is a slew of scientific papers about it.

There have been several suggestions that the differential warming of
the Arctic and the Tropics will weaken the Jet Stream due to a
reduction in thermal contrast. This weakening of the Jet would then
lead to large meanders in the Stream and long spells of severe
weather, either cold or hot. This idea seems to have been accepted
though it bothered me a bit when I actually started to think about it.

I recall being taught (which I accept does not necessarily mean I was
taught) that slow-moving or stationary upper waves are associated with
a strong Jet; small, transitory waves are associated with weak Jet
Streams.

Then I found an article by CEP Brooks in an online 1950 issue of
Weather which said more or less the same thing. It also said that
they'd expected a weakening of upper winds due to the differential
warming that had occurred before WWII and had been surprised to find
that they'd strengthened instead.

At lower levels in the atmosphere, the number of Atlantic gales affecting the UK has dropped significantly this century compared to much of the last century. THe winter of 2013/14 was exceptional, but even then not for the number of gales, more for the quite exceptional sea conditions in the SW largely, due to the unusual track of the depressions. (We got the seas normally reserved for western Ireland.)

At my site in Penzance there were an average of 14 gales per annum 19993-2002 - broadly in line with Lambs observations. The following 10 years saw an exceptionally low average of 5.5 per annum


One thing that has an effect on the atmospheric circulation, as I've
said before, is the pattern of SST anomalies, particularly in the Grand
Banks region.

--
Graham P Davis, Bracknell, Berks. [Retd meteorologist/programmer]

I think that it's an easy option for the media to go back 1 step and blame everything on the Jet Stream. I agree that the SST anomalies have an influence, but this years N Atlantic SST anomalies can be blamed on the winds in that area over the late winter period. But what caused that anomalous set up? It's all about how far back you want to go.

Interesting area though

Graham
Penzance

On Tuesday, 11 August 2015 13:10:19 UTC+1, Graham Easterling wrote:
On Tuesday, August 11, 2015 at 11:46:00 AM UTC+1, Graham P Davis wrote:
On Tue, 11 Aug 2015 02:35:01 -0700 (PDT)
xmetman wrote:

After listening to Carole Kirkwood talking about what a wet and cold
summer its been over Scotland this year on this mornings Breakfast
Weather, it does seem to me that as far as the media are concerned
most of today's weather woes in this country today, including this
one can be blamed on the jet stream, or lack of jet stream, or the
position of the jet stream. So if the answer to most of the world's
climate problems is the ubiquitous "jet stream", what about its part
in global warming? I haven't seen any research that looks into the
role jet streams play in global warming, but I'm sure it won't be
long before there is a slew of scientific papers about it.

There have been several suggestions that the differential warming of
the Arctic and the Tropics will weaken the Jet Stream due to a
reduction in thermal contrast. This weakening of the Jet would then
lead to large meanders in the Stream and long spells of severe
weather, either cold or hot. This idea seems to have been accepted
though it bothered me a bit when I actually started to think about it.

I recall being taught (which I accept does not necessarily mean I was
taught) that slow-moving or stationary upper waves are associated with
a strong Jet; small, transitory waves are associated with weak Jet
Streams.

Then I found an article by CEP Brooks in an online 1950 issue of
Weather which said more or less the same thing. It also said that
they'd expected a weakening of upper winds due to the differential
warming that had occurred before WWII and had been surprised to find
that they'd strengthened instead.

At lower levels in the atmosphere, the number of Atlantic gales affecting the UK has dropped significantly this century compared to much of the last century. THe winter of 2013/14 was exceptional, but even then not for the number of gales, more for the quite exceptional sea conditions in the SW largely, due to the unusual track of the depressions. (We got the seas normally reserved for western Ireland.)

At my site in Penzance there were an average of 14 gales per annum 19993-2002 - broadly in line with Lambs observations. The following 10 years saw an exceptionally low average of 5.5 per annum


One thing that has an effect on the atmospheric circulation, as I've
said before, is the pattern of SST anomalies, particularly in the Grand
Banks region.

--
Graham P Davis, Bracknell, Berks. [Retd meteorologist/programmer]

I think that it's an easy option for the media to go back 1 step and blame everything on the Jet Stream. I agree that the SST anomalies have an influence, but this years N Atlantic SST anomalies can be blamed on the winds in that area over the late winter period. But what caused that anomalous set up? It's all about how far back you want to go.

Interesting area though

Graham
Penzance

I think you've mentioned this before, Graham, and to me it seems very significant but not well known. Do other places in the UK show a similar trend? The current orthodoxy among non-scientists, especially journalists, is that it's going to get stormier and that is going to cause all manner of dire effects. I even have a friend (he stood for the Greens in a local election) who insists this is what will happen. It seems that even the Good Guys have their fundamentalists and very tiresome they can be.
One study I have seen predicts the jet stream will move north but could actually be stronger in certain zones. Overall it seemed that the mean wind speed in the UK would be little changed.

Tudor Hughes, Warlingham, Surrey.

On Tuesday, August 11, 2015 at 4:17:21 PM UTC+1, Tudor Hughes wrote:
On Tuesday, 11 August 2015 13:10:19 UTC+1, Graham Easterling wrote:
On Tuesday, August 11, 2015 at 11:46:00 AM UTC+1, Graham P Davis wrote:
On Tue, 11 Aug 2015 02:35:01 -0700 (PDT)
xmetman wrote:

After listening to Carole Kirkwood talking about what a wet and cold
summer its been over Scotland this year on this mornings Breakfast
Weather, it does seem to me that as far as the media are concerned
most of today's weather woes in this country today, including this
one can be blamed on the jet stream, or lack of jet stream, or the
position of the jet stream. So if the answer to most of the world's
climate problems is the ubiquitous "jet stream", what about its part
in global warming? I haven't seen any research that looks into the
role jet streams play in global warming, but I'm sure it won't be
long before there is a slew of scientific papers about it.

There have been several suggestions that the differential warming of
the Arctic and the Tropics will weaken the Jet Stream due to a
reduction in thermal contrast. This weakening of the Jet would then
lead to large meanders in the Stream and long spells of severe
weather, either cold or hot. This idea seems to have been accepted
though it bothered me a bit when I actually started to think about it..

I recall being taught (which I accept does not necessarily mean I was
taught) that slow-moving or stationary upper waves are associated with
a strong Jet; small, transitory waves are associated with weak Jet
Streams.

Then I found an article by CEP Brooks in an online 1950 issue of
Weather which said more or less the same thing. It also said that
they'd expected a weakening of upper winds due to the differential
warming that had occurred before WWII and had been surprised to find
that they'd strengthened instead.

At lower levels in the atmosphere, the number of Atlantic gales affecting the UK has dropped significantly this century compared to much of the last century. THe winter of 2013/14 was exceptional, but even then not for the number of gales, more for the quite exceptional sea conditions in the SW largely, due to the unusual track of the depressions. (We got the seas normally reserved for western Ireland.)

At my site in Penzance there were an average of 14 gales per annum 19993-2002 - broadly in line with Lambs observations. The following 10 years saw an exceptionally low average of 5.5 per annum


One thing that has an effect on the atmospheric circulation, as I've
said before, is the pattern of SST anomalies, particularly in the Grand
Banks region.

--
Graham P Davis, Bracknell, Berks. [Retd meteorologist/programmer]

I think that it's an easy option for the media to go back 1 step and blame everything on the Jet Stream. I agree that the SST anomalies have an influence, but this years N Atlantic SST anomalies can be blamed on the winds in that area over the late winter period. But what caused that anomalous set up? It's all about how far back you want to go.

Interesting area though

Graham
Penzance

I think you've mentioned this before, Graham, and to me it seems very significant but not well known. Do other places in the UK show a similar trend? The current orthodoxy among non-scientists, especially journalists, is that it's going to get stormier and that is going to cause all manner of dire effects. I even have a friend (he stood for the Greens in a local election) who insists this is what will happen. It seems that even the Good Guys have their fundamentalists and very tiresome they can be.
One study I have seen predicts the jet stream will move north but could actually be stronger in certain zones. Overall it seemed that the mean wind speed in the UK would be little changed.

Tudor Hughes, Warlingham, Surrey.

The slightly surprising thing is that there have been reductions in gale frequencies this century right up the Atlantic seaboard of the UK, so it would appear not to be due to Atlantic depressions taking, on average, a more northerly course.

Perhaps more 'meanders' in the jet stream are causing depressions to sit longer in mid Atlantic rather than progress across the UK? (Just an idea - I've no real evidence to support it).

Graham
Penzance

On 11/08/2015 16:17, Tudor Hughes wrote:
I think you've mentioned this before, Graham, and to me it seems very significant but not well known. Do other places in the UK show a similar trend? The current orthodoxy among non-scientists, especially journalists, is that it's going to get stormier and that is going to cause all manner of dire effects. I even have a friend (he stood for the Greens in a local election) who insists this is what will happen. It seems that even the Good Guys have their fundamentalists and very tiresome they can be.
One study I have seen predicts the jet stream will move north but could actually be stronger in certain zones. Overall it seemed that the mean wind speed in the UK would be little changed.

I find the rhetoric coming out from 'green' NGOs and other interested
parties that the world is going to turn 'nasty' if the world warms
rather odd given our knowledge of the past climate.

Every time I hear somebody say that it is going to be a disaster if the
world warms more than say, 2C it makes me think of the Eocene Optimal.

The one that sticks out is oceanic acidification. During the Eocene the
world was warm right to the Arctic Circle and temperate diciduous
forests grew in the Artic and on Antarctic. The CO2 levels have been
estimated to be around 700 to 900 ppm and some estimates have put that
figure as high as 2000 ppm. Yet the seas were tropical over most of the
globe with coral reefs in far greater abundance than now. The world must
have been a more beautiful place with no areas frozen/ice bound for many
months every year, or as in the case of Antartic - practically life-less.

--
Nick Gardner
Otter Valley, Devon
20 m amsl
http://www.ottervalley.co.uk

In message , Nick Gardner
writes
Every time I hear somebody say that it is going to be a disaster if the
world warms more than say, 2C it makes me think of the Eocene Optimal.

The one that sticks out is oceanic acidification. During the Eocene the
world was warm right to the Arctic Circle and temperate diciduous
forests grew in the Artic and on Antarctic. The CO2 levels have been
estimated to be around 700 to 900 ppm and some estimates have put that
figure as high as 2000 ppm. Yet the seas were tropical over most of the
globe with coral reefs in far greater abundance than now. The world
must have been a more beautiful place with no areas frozen/ice bound
for many months every year, or as in the case of Antartic - practically
life-less.

The Arctic regions have a beauty of their own IMO. Also there must be
more diversity of environments now than there was in the Eocene, and
arguably that's a good thing.

I suspect that we could manage to cope with a rise in mean global
temperature of 2 or 3 degrees if it wasn't for the effect it would have
on sea-level. A high proportion of the world's population lives in
low-lying areas, and many of our biggest cities are coastal ones. If
much of the Greenland ice sheet should melt we are likely to be in big
trouble, and should the East Antarctic ice sheet ever melt it would be
catastrophic.
--
I'm not paid to implement the recognition of irony.
(Taken, with the author's permission, from a LiveJournal post)

On Tuesday, August 11, 2015 at 7:17:33 PM UTC+1, Nick Gardner wrote:
On 11/08/2015 16:17, Tudor Hughes wrote:
I think you've mentioned this before, Graham, and to me it seems very significant but not well known. Do other places in the UK show a similar trend? The current orthodoxy among non-scientists, especially journalists, is that it's going to get stormier and that is going to cause all manner of dire effects. I even have a friend (he stood for the Greens in a local election) who insists this is what will happen. It seems that even the Good Guys have their fundamentalists and very tiresome they can be.
One study I have seen predicts the jet stream will move north but could actually be stronger in certain zones. Overall it seemed that the mean wind speed in the UK would be little changed.

I find the rhetoric coming out from 'green' NGOs and other interested
parties that the world is going to turn 'nasty' if the world warms
rather odd given our knowledge of the past climate.

Every time I hear somebody say that it is going to be a disaster if the
world warms more than say, 2C it makes me think of the Eocene Optimal.

The one that sticks out is oceanic acidification. During the Eocene the
world was warm right to the Arctic Circle and temperate diciduous
forests grew in the Artic and on Antarctic. The CO2 levels have been
estimated to be around 700 to 900 ppm and some estimates have put that
figure as high as 2000 ppm. Yet the seas were tropical over most of the
globe with coral reefs in far greater abundance than now. The world must
have been a more beautiful place with no areas frozen/ice bound for many
months every year, or as in the case of Antartic - practically life-less.

--
Nick Gardner
Otter Valley, Devon
20 m amsl
http://www.ottervalley.co.uk

A couple of points Nick.

1, The Eocene Optimal had a temperature rise nothing like as rapid as this one has been and the current rise is more likely to accelerate, than it is to slow down.

2. There were not 6 billion people around.

Nick, watching today's news, it seems like a New Ice Age is on its way to Scotland first!
http://youtu.be/vuirnxRD1og

"xmetman" wrote in message
...

I'm sure that the phrase "jet stream" will be cropping in many conversations
about the weather in the coming years, you can easily picture one old dear
saying to another in a bus queue "I know Enid the weather has been simply
terrible, and you know it's all down to the orientation of the Jet stream
over Iceland you know".

=========================

Didn't we get a bad summer a few years ago when even people in the bus queue
were blaming the Jet Stream?

I monitored the jet stream for a few months and the weather here did seem to
be bad - wet and windy - when the jet stream was passing over the UK. It is
also hot here in summer when the Jet Stream is to the north of us.

The current Jet Stream is shown he
http://virga.sfsu.edu/gif/jetstream_atl_init_00.gif
And it position 6 days ahead he
http://virga.sfsu.edu/gif/jetstream_atl_h120_00.gif

Does that mean it is going to be cold nex Sunday?

Cheers, Alastair.