Topic: Vorticity

[Mike]

I would like some comments re something I was pondering this week while watching CUs maturing.  I think the following is self-explanatory - I didn't want to put too much as it gets pretty confusing to me!

Was in the park leaning up against a tree as one does during lunch reading Bluestein's thunderstorm/tornado book and reading up on vertical/horizontal shear.  Now having the beneift of an ocean view and moderate CUs convecting in front of me to compare with the book, can i give an example and if you could either pass or fail me in my presumptions.
 
 
Scenario of horizontal vorticity: The CUs had moderate convective growth.  The towers were well formed and the caps were rising to the tropopause nicely.  The tower structure was nice with plenty of bouyancy evident and as the caps reached their achieved level the towers then bent to the S/SE with the CUs moving N/NE.  I can't give heights in exact numbers but they were moderate in scale.
 
  Now with the winds on the sounding today generating winds below 500 from the east at about 10-15kts and 90% of the winds above 500 were from either the W or NW but they were weaker in speed, would this show that the horizontal vorticity is predominantly from the W ?   Given that, why did the tops once dissipating bend in that direction if the majority of winds were from the opposite direction?  The winds aloft were light. Is it the case that the lower level winds and what i was observing was corrent as per the actual height the towers were at say 3 to 6 Km high?  Was it the caps being pushed over or the storm's lower half being bent due to stronger winds?
 
Is vertical vorticity simply the vertical force of the updraughts associated with speed shear ?  If the speed shear does not include directional shear would that indicate at least some stability for the tower to maintain structure/longevity and in essence vorticity?  I think significant speed and directional shear are required for mesos - but that's another question.

On a sounding is that easily recognised or interpreted from the wind profiles.

mike
 

[Mike]

Thank you, John.

So vertical vorticity is really in connection with the production of mesos within a storm - ie the bending of horizontal shear tilting vertical due to speed/directional shear when it's significant?

So if a storm shows strong rigid towers that has nothing to do with vertical vorticity, it's just displaying a strong updraught and a decent convective layer?

So how can one tell if you had strong vertical vorticity - supercells and rotation?  Severe pulse storms showing vertical vorticity would rotate to some degree then?

I'm trying to get the observation part of it down pat - i have the horizontal right, but it's the vertical - perhaps i'd never see it up here with our storms unless they were very nasty severe jobs...?

Mike

[Mike]

Yes, I see.  They were just observatory questions hence my asking, but you have answered them for me.  Interesting yet very complex and I suspect I'll have to work now on divergence and convergence aspects and understand that in relation to vorticity. I'm sure others reading this will definitely get something out of it as I have.

It's coming together at least one step at a time!

Helpful answers, thanks.

Mike

[Mike]

My list is vast and seems how you like typing, you'll no doubt relish the thought.  Count me in. Will PM the list down the track for you to ponder and scribe!

[Michael Bath]

I think some diagrams would help with this discussion as I'm not sure what is being explained. Mike - you could perhaps do some too now that you know the answers

regards, Michael

[Mike]

Yeah right MB!  I can add some diagrams in the discussion here and perhaps John can interpret for all..will do so tomorrow and dig some juicy ones out.  This could prove most educational indeed.

Mike

[Mike]

Here's some diagrams, John.  They are from different events relating to from supercell/tornado development etc but others are wind/pressure profiles.  Perhaps you might like to start with one image at a time with comments so we're not swapping between maps and comments and confusing it all.  I hope they are what you wanted.  When you mentioned high and low pressure areas it dawned on me that vorticity is also related to the convergence of these boundaries of opposing wind profiles associated with them from different areas - I know what i meant!

Mike