Volcanic Tornado-Photo

[Greg Blumberg]

The only thing I could find was a paper from the Bulletin of Vulcanology from 1965. The author, R Nagasawa, proposes that the rotation is due to Coriolis Effect. I would think that the shear is a product of interaction of the wind with the terrain and accelerates due to convection and the conservation of angular momentum.

This link is for a preview but there is a link where the full paper can be purchased.
Article

I'm pretty sure the Coriolis Force has a very little effect on vortexes that small. I was taught that it was part of how the pressure gradient force equations work in cyclostrophic winds (when centripetal forces balance the pressure gradient force such as in a tornado.) Any ideas of why this wouldn't hold true to this specific phenomena?

 

[George Kourounis]

These are steam devils (albeit larger ones), small-scale vorticies on par with dust devils/fire devils. I don't think I've even heard a term coined for them, "volcano devils", maybe? The steam/ash clouds are stretching simple low-level vorticity rather than having mesocyclones or any type of storm structure. I wouldn't go so far to call these tornadoes, not even landspouts - I think a 'devil' vortex variant is more fitting.

I think the thick condensation funnel on the Hawaiian one is due to the copious amounts of steam rising off of the near-boiling ocean surface (warmed by direct lava contact) - the air over the ocean is likely near saturation at that spot.

Pretty awesome photos/videos nonethless...

I have witnessed countless steam devils over the years, mostly on the Great Lakes on days when the air temperature drops over top a relatively warm body of water. If the wind currents are just right, and there is enough vorticity, the steam swirls up, just like a dust devil.

I have also seen volcanic steam devils on White Island volcano in New Zealand. In this case, the water was warmed by the volcanic activity and the surrounding air was cool enough for a temperture gradient to produce steam.

Both the picture from Kilauea and the video from Etna are classic examples of small scale, volcanically produced steam devils, although the Etna one was very large.

Steam Devils on Lake Ontario:

More photos here:
http://www.stormchaser.ca/Steam_Devils/2008_02_28_Steam and Ice/2008_02_28_Steam and Ice.html
http://www.stormchaser.ca/Steam_Devils/2008_01_03_Steam_Devils/2008_01_03_Steam_Devils.html
http://www.stormchaser.ca/Steam_Devils/2007_03_06_Steam/2007_03_06_Steam.html
http://www.stormchaser.ca/Steam_Devils/2004_01_10_Steam/2004_01_10_Steam.html

Volcanic Steam Devils at White Island volcano:

More White Island steam devils:
http://www.stormchaser.ca/Volcanoes/White_Island/White_Island_Steam_Devils.html


George Kourounis
www.stormchaser.ca

 

[Karla Dorman]

Never heard of this, either - WOW. Crazy/amazing!

 

[Wes Carter]

I'm pretty sure the Coriolis Force has a very little effect on vortexes that small. I was taught that it was part of how the pressure gradient force equations work in cyclostrophic winds (when centripetal forces balance the pressure gradient force such as in a tornado.) Any ideas of why this wouldn't hold true to this specific phenomena?

You're right, Coriolis Force has little affect on anything smaller than the synoptic scale. Some would argue that point because of the tendency of tornadoes to rotate counterclockwise in the Northern Hemisphere but that relationship is indirect. But the difference in velocity of the rotation of the Earth between the northern part and southern part of these vortices is not great enough to impart any measurable or consequential Coriolis Force.


I'm reading about Rossby numbers and their calculations which fits in with this discussion. This page might be of interest to you.

Please keep in mind that I don't have any formal atmospheric sciences nor meteorology training so take anything I put out there with a grain of salt. Please feel free to call me out if I'm putting out bad info.