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View Full Version : MET - JETSTREAMS / TROPOPAUSE


Natstrackalpha
28th Apr 2012, 09:00
Hi,

I have a question which is not a challenge, nor a trick question, it is a cry for knowledge.

Understanding that the Polar Jets in the N.Hemisphere are invaribly at the tropopause.

My question is: are the Jetstreams AT the tropopause or just above or below the tropopause. [I know the CORE is slightly higher and to the Polar side of the jet but in the jet] Also = is it the case that there is absolutlely zero weather above the tropopause as is studied, and assuming nil wx at or above the tropopause then could there still be Jetstreams above the tropopause. I am trying to solidfy my education here.

Also (sorry) - subject to the above - if there is no wx above the tropopause and say, no jetstreams then ---would it be possible to get CAT in/at these areas/levels.

Sorry if this is a p--n in the ---e question.

You could answer with "go and read up on MET and Climatology" - well, I have but these questions have not yet crystalised.

Visualising a large CB, say, over the N. Atlantic, well developed and moving from the mature to the disipating stage, the anvil will start to pan out in the direction of the upper winds (even the jet) and, above that anvil would possibly be mod to severe turb from the CB, from the convective currents (unless these currents have just stopped dead at the tropo), indeed the Jets may in fact be not far away from here as they (the jets) are the main engines of most if not all of our weather - as you all know.

Stretching the question a tiny stage further - say we were to fly a Blackbird at something like FL800 or 900 and we were well above any WX (and saw the curvature of the Earth etc.,) then could we experience any turb or indeed any wind at that level?

Why do I want to know? I was just trying to see what it is like trucking around at FL410 or more.

Thank you for your time.

-and your patience.

Piltdown Man
28th Apr 2012, 15:47
You mustn't confuse met theory with real life. Northern hemisphere jets appear to whip along just under the tropopause, but they choose their centres. Typically, they appear to be higher rather than lower. But if anyone says "In an exam..." follow their advice, not mine.

As for weather, I've rarely encountered any at FL410 but I have been bounced around by some of the most unpleasant (non-CB related) turbulence.

Above CB's (Europe 40-60 North), I've rarely encountered turbulence. It is does exist for sure but I'm not that worried about it. What I don't like are long squall lines. Trying to find (safe-ish) crossing points might involve detours of hundreds of miles.

As for what's above 410, I haven't a clue. Of the top of my head I'll guess that there's not a lot.

MarkerInbound
28th Apr 2012, 16:40
Not too often but I have radar reports of CB tops hitting 70,000 in the central US. Something that can stand straight up in a 100 kt wind, I don't want to have anything to do with it.

Natstrackalpha
5th May 2012, 10:34
Thanks for your posts guys. Few words yet great enlightenment.