There is an interesting video here about the latest thinking on the Jet
Stream:
http://www.youtube.com/watch?v=_nzwJ...layer_embedded

But apparently the ideas there are disputed:
http://www.climatecentral.org/news/n...er-links-16375

Cheers, Alastair.

On Monday, August 26, 2013 10:49:17 AM UTC+1, Alastair wrote:
There is an interesting video here about the latest thinking on the Jet

Stream:

http://www.youtube.com/watch?v=_nzwJ...layer_embedded



But apparently the ideas there are disputed:

http://www.climatecentral.org/news/n...er-links-16375



Cheers, Alastair.
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I remain unconvinced, as others do, about this greater amplitude of the waves with a slower zonal wind speed u.

For a start, 15 years is a piddly time period in the climate change scenario.

I can't see that it follows from Rossby wave theory.
Phase speed of Rossby waves increases with wavelength.
Rossby waves will move east or west depending
on the relative magnitude of
phase speed c and zonal wind speed u.

Very large wavelength Rossby waves move westward, as cu.
Short wavelength Rossby waves move eastward, as uc.

But there is an in-between-wavelength where u=c.

These are stationary waves,
with wavelengths between 5000 and 10,000 km.

So the slower the flow the more likely the stationary waves is not necessarily so.

Also, there is a feedback going on between the baroclinic waves(depressions) and the Rossby waves.

The charts she shows really just show the baroclinic flow albeit influenced by the Rossby effect.

You might like to see this paper which attempts to model the possibilities.

http://onlinelibrary.wiley.com/doi/1....1415/abstract

Len
Wembury

"Len Wood" wrote in message
...
On Monday, August 26, 2013 10:49:17 AM UTC+1, Alastair wrote:
There is an interesting video here about the latest thinking on the Jet

Stream:

http://www.youtube.com/watch?v=_nzwJ...layer_embedded



But apparently the ideas there are disputed:

http://www.climatecentral.org/news/n...er-links-16375



Cheers, Alastair.
------------------------------------------------------------------------------
I remain unconvinced, as others do, about this greater amplitude of the
waves with a slower zonal wind speed u.

For a start, 15 years is a piddly time period in the climate change
scenario.

I can't see that it follows from Rossby wave theory.
Phase speed of Rossby waves increases with wavelength.
Rossby waves will move east or west depending
on the relative magnitude of
phase speed c and zonal wind speed u.

Very large wavelength Rossby waves move westward, as cu.
Short wavelength Rossby waves move eastward, as uc.

But there is an in-between-wavelength where u=c.

These are stationary waves,
with wavelengths between 5000 and 10,000 km.

So the slower the flow the more likely the stationary waves is not
necessarily so.

Also, there is a feedback going on between the baroclinic
waves(depressions) and the Rossby waves.

The charts she shows really just show the baroclinic flow albeit
influenced by the Rossby effect.

You might like to see this paper which attempts to model the
possibilities.

http://onlinelibrary.wiley.com/doi/1....1415/abstract

Len
Wembury

Thanks for that link, but the paper is well beyond me :-)

My reason for posting the video was that thought it was easy to understand.
I was surprised when I discovered it had been criticised, but thought I
ought to add that link "to provide balance".

Although 15 years is a short time in climatic terms, the melting of the
Arctic ice has only been obvious for that length of time, and so its effects
would only be obvious over that period. But I won't jump to conclusions, and
just wait and see what happens.

Cheers, Alastair.