Twin horseshoe vortices

[Jon Davies]

I dug out some photos that my wife Shawna took in Nebraska on a June chase this year. There were some interesting pics she took of twin horseshoe vortices. For those interested, I did a little write up with photos and diagrams at: http://davieswx.blogspot.com

It's probably not that unusual, but has anyone else seen twin horseshoe vortices like these?

Jon Davies

www.jondavies.net

 

[Dennis Sherrod]

Jon,
Neat, I have seen a few of these and was not familiar with what they were called or the reasoning. From your experience, is it also possible for these to be larger in diameter and horizontal? I have a picture of a similar structure from this year, but it is as I just described, horizontal and not vertical.

 

[Jeff Duda]

The following is an excerpt from a Doswell paper that I'll cite after this. It should explain the situation at least somewhat.

Meteorologists operating on storm intercept teams have observed relatively long-lived funnel clouds in association with quite ordinary cumulus clouds (Fig. 7). A rather different phenomenon has been observed on fair weather days, the so-called "horseshoe vortices" (Fig. 8). These may arise in much the same way as "mountainadoes" (Bergen 1976): tilting and the associated stretching of an enhanced region of horizontal vorticity over some upward-protruding object, or perhaps by an isolated updraft (a small cumulus-scale version of the process depicted in Fig. 3a of Klemp 1987).

Doswell, C. A. III, and D. W. Burgess, 1993: Tornadoes and tornadic storms: A review of conceptual models. The Tornado: Its Structure, Dynamics, Hazards, and Prediction, Geophys. Monogr., No. 79, Amer. Geophys. Union, 161–172.

I'm actually citing this reference in a paper I'm writing