The Upper Part of Tornadoes

[Jeff Miller]

I am curious about the windflow with the upper part of tornadoes. Radar has given us great 3D renderings, and I know there is little to know - but what are some theories about what happens to the upper part of tornadoes.

Do they lean way over into a horizontal axis?
Do they simply diverge out into all directions?
Is the Overshooting cap literally the tornadic circulation itself in cases where the circulation does not lean?
Or are there simply too many variables?

 

[Stephen Levine]

Tornado Top

Interesting question, one I suspect will get very scientific responses based upon computer modelling.
Mine is specifically right-brained, and it may sound off-beat yet I know it is quite valid:
For years during my highschool, college days and beyond - back in the 70's I meditated on the nature and essence of tornadoes and the insides of thunderstorms from high elevations.
In any event, during one exquisitely spacy and powerful jazz song, a whole sequence of elevating upwards along side a tornado came to me and eventually in the mind movie, I ended up above it.
What I saw was a huge bowl, funnel shaped and brown from the dust picked up from the earth. It was quite huge, and a part of a very cauliflowery CB type cloud that attached to a much higher topped main storm shield.
The entire sky above the bowl was tinged an eerie brownish from all the dust thrown into the atmosphere -including the cauliflowery tops, and as I looked deep into the brown tinged darkness at the heart of the huge bowl from above, I could see that it was slowly rotating, and small pieces of debris were being ejected upwards and out of it into the air above.
It was very powerful and eerie.
That's my meditative experience of being above a tornado, and long before computer modelling ever showed that indeed a tornadic section of the storm is frequently lower topped than the main storm shield.

 

[Mike Hollingshead]

I did that once, but I saw a purple elephant up there swirling his trunk around the top of the storm.

 

[Bob Hartig]

Now THAT is one heck of an interesting question! That's my initial reaction, and it's a bit fuzzy, fortified as it is right now by a couple mugs of Hopnoxious IPA. But I'd say it regardless. With so much interest in what's happening near the ground in regard to tornadogenesis, it's worth thinking about what happens at the top of the vortex, where a tornado finally peters out. How does that happen?

I've thought about this myself from time to time, just never dwelt on the matter. You've articulated the possibilities very well.

Question: doesn't the overshooting top tend to collapse just prior to tornado formation? That would suggest to me that it's not a manifestation of a tornado's "exhaust." But it does seem to be linked with some kind of overall process in at least some tornadoes' life cycles.

 

[Shane Adams]

You'd think science would easily know more about the "top" part of a tornado, since all these DOW readings are taken hundreds of feet off the ground.

 

[rdale]

I'd have to think that the tornado is related to something in the storm WELL above a few hundred feet...

 

[Shane Adams]

I'd have to think that the tornado is related to something in the storm WELL above a few hundred feet...

Which brings me to my next point...exactly where is the top of a tornado?

 

[Maggie Kahman]

Which brings me to my next point...exactly where is the top of a tornado?

omg....That is a very good question, Shane. One that will have me scratching my head for a LONG time.

 

[Glen Romine]

You'd think science would easily know more about the "top" part of a tornado, since all these DOW readings are taken hundreds of feet off the ground.

DOW observations are generally only of the lowest 3 km or so of the storm (and typically missing the lowest few hundred feet). Most of the research interest has been on trying to understand how such strong rotation develops at the ground. Since this is the part of the tornado that impacts people, this seems reasonable. There have been some quality observations of the depth of the tornadic circulation, such as airborne observations during the VORTEX experiment described by Wakimoto and others. These have shown the circulation indeed extends deep into the storm. Of course, at the top of the storm, the updraft is weakening with height, and so the stretching that helped intensify the circulation at low-levels is now acting opposite in sign, relaxing /expanding the circulation. Numerical simulations of tornadoes are generally of two types, those with a parent storm or those replicating something more like a full-sized tornado simulator. Most of the tornadoes in simulations with storms are generally shallow vortices, though not all. In simulations I've looked at some, I don't recall anything particularly interesting going on up there that caught my eye. But, certainly there could be meaningful information at storm top and simulations may or may not offer much help with what goes on in the real atmosphere.

 

[Bob Schafer]

I imagine that stretching occurs below the altitude where greatest instability is found. Above that level, wouldn't vertical convergence and horizontal divergence be the rule?

edit: Eh, on second thought, I guess stretching persists right up to the EL.

 

[Bob Hartig]

I wonder if there aren't a few possible scenarios. I'm thinking of the dynamic pipe effect and anticyclonic tornadoes.

Last September, during a cold core chase in Iowa, my buddies and I were watching a small wall cloud, with what looked to be a slight nub of a funnel, turning slowly anticyclonically. While that was going on maybe a half-mile in front of us, I happened to glance off to the east-southeast and noticed a rope funnel maybe two miles distant. It occurred to me that the two funnels might have been connected to each other, just far ends of a long, rotating pipe stretching through the storm. Of course, that's just conjecture and I'm no scientist, but I know there's theory (i.e. streamwise vorticity tilted upwards by an updraft) to support the idea.

 

[Doug Lee]

Which brings me to my next point...exactly where is the top of a tornado?

Well, if you go by the official definition of a tornado, the top of the tornado in at the base of the parent thunderstorm.

Now as to where the top of the rotating updraft is, I would imagine that it is somewhere around the anvil. I'm sure someone will chime in with a more scientific definition or explaination.

 

[Paul Austin]

I wonder if there aren't a few possible scenarios. I'm thinking of the dynamic pipe effect and anticyclonic tornadoes.

Last September, during a cold core chase in Iowa, my buddies and I were watching a small wall cloud, with what looked to be a slight nub of a funnel, turning slowly anticyclonically. While that was going on maybe a half-mile in front of us, I happened to glance off to the east-southeast and noticed a rope funnel maybe two miles distant. It occurred to me that the two funnels might have been connected to each other, just far ends of a long, rotating pipe stretching through the storm. Of course, that's just conjecture and I'm no scientist, but I know there's theory (i.e. streamwise vorticity tilted upwards by an updraft) to support the idea.

Reminds me of the Pierce, NE double funnel video. Of course, this looks like the opposite of what you're describing, but fascinating nonetheless - truly bizarre behavior.

http://www.youtube.com/watch?v=BezK0rkMcWk
http://www.youtube.com/watch?v=L-YZqBYtM9U&feature=related