"Pan turbulence"

[Martin Gregorie]

Some time back I saw a magazine article about something mysterious
called "pan turbulence" that bit airliners in clear air, often
somewhere in the middle of the USA.

Could this have been plain old rotor by any chance?

I was reminded to ask this by the message about the "Rodeo In The Sky"
TV program.
--
martin@ : Martin Gregorie
gregorie : Harlow, UK
demon :
co : Zappa fan & glider pilot
uk :

[Eric Greenwell]

In article >,
says...
>Some time back I saw a magazine article about something mysterious
>called "pan turbulence" that bit airliners in clear air, often
>somewhere in the middle of the USA.
>
>Could this have been plain old rotor by any chance?

I've not heard of pan, but only of CAT (clear air turbulence), which I
think is often caused by wind shear, particularly near the jet stream.
--
-------
Eric Greenwell USA

[Martin Gregorie]

On Thu, 2 Oct 2003 06:51:43 -0700, Eric Greenwell
> wrote:

>In article >,
says...
>>Some time back I saw a magazine article about something mysterious
>>called "pan turbulence" that bit airliners in clear air, often
>>somewhere in the middle of the USA.
>>
>>Could this have been plain old rotor by any chance?
>
>I've not heard of pan, but only of CAT (clear air turbulence), which I
>think is often caused by wind shear, particularly near the jet stream.

I'd wondered what CAT was too, thanks for the clarification. However,
this was not CAT: it was definitely referred to as 'pan' or 'pancake'
turbulence and, as I now recall some mention of mountains in the area,
I bet it was really rotor. I've never seen this term used before or
since: in the context of the article pancake turbulence was a totally
new, scary thing.

Comments?

--
martin@ : Martin Gregorie
gregorie : Harlow, UK
demon :
co : Zappa fan & glider pilot
uk :

[Jack Glendening]

Bob Johnson wrote:
> Well, Google has heard of it, so it must be real. Dr. Jack could comment
> on it, but I'll wager we wouldn't be any smarter.

I hadn't heard of "pancake" turbulence, but since you posted the link I
checked it out and although I've never seen a "Lumley diagram" before my
interpretation is the following. "Turbulence" is a rapid fluctuation in
velocity, and those velocity fluctuation can be in any of 3 directions
(1 vertical, 2 horizontal). In "pancake turbulence" the velocity
fluctuations in the vertical direction are much smaller in magnitude
than the velocity fluctuations in the horizontal direction. (In
"isotropic" turbulence, which might also be called "fully developed
turbulence", the velocity fluctuations are of equal magnitude in all
three directions.) Don't know if that makes you any smarter or not!

DrJack

[Jack Glendening]

To put it in an aircraft framework, in riding through "pancake
turbulence" you will get bounced from side-to-side, but not up-and-down.

[Martin Gregorie]

On Fri, 03 Oct 2003 04:04:15 GMT, Jack Glendening
> wrote:

>To put it in an aircraft framework, in riding through "pancake
>turbulence" you will get bounced from side-to-side, but not up-and-down.
>

Thanks for the explanation.

--
martin@ : Martin Gregorie
gregorie : Harlow, UK
demon :
co : Zappa fan & glider pilot
uk :

[Bob Johnson]

Dr. Jack --

That's a wonderful explanation, I lose my wager happily. I assume the
"cigar" could really be a bear!

BJ

Jack Glendening wrote:
>
> To put it in an aircraft framework, in riding through "pancake
> turbulence" you will get bounced from side-to-side, but not up-and-down.

[Bruce Greeff]

Clearly the Northern soaring season is over...

Jack Glendening wrote:
> I find I can't resist pointing out that if one was to consider the
> "turbulence" created by following the vectors of a person's center of
> mass while in bed, with one person sleeping in the bed one would find
> that one had a case of "pancake turbulence". With two people, however,
> quite likely there could be an interspersed episode(s?) of "cigar
> turbulence" in which, for a short time, the velocity fluctuations were
> primarily vertical oriented rather than horizontally oriented.
>